Patent Publication Number: US-2015063213-A1

Title: Wireless communication methods and apparatus using beacon signals

Description:
RELATED APPLICATIONS 
     The present application is a division of U.S. patent application Ser. No. 11/652,245 filed on Jan. 10, 2007 titled “Wireless Communication Methods and Apparatus Using Beacon Signals” now U.S. Pat. No. ______ incorporated by reference in its entirety herein that claims the benefit of U.S. Provisional Patent Application Ser. No. 60/758,011 filed on Jan. 11, 2006, titled “METHODS AND APPARATUS FOR USING BEACON SIGNALS FOR IDENTIFICATION, SYNCHRONIZATION OR ACQUISITION IN AN AD HOC WIRELESS NETWORK”, U.S. Provisional Patent Application Ser. No. 60/758,010 filed on Jan. 11, 2006, titled “METHODS AND APPARATUS FOR FACILITATING IDENTIFICATION, SYNCHRONIZATION OR ACQUISITION USING BEACON SIGNALS”, U.S. Provisional Patent Application Ser. No. 60/758,012 filed on Jan. 11, 2006, titled “METHODS AND APPARATUS FOR USING BEACON SIGNALS IN A COGNITIVE RADIO NETWORK”, U.S. Provisional Patent Application Ser. No. 60/863,304 filed on Oct. 27, 2006, U.S. Provisional Patent Application Ser. No. 60/845,052 filed on Sep. 15, 2006, and U.S. Provisional Patent Application Ser. No. 60/845,051 filed on Sep. 15, 2006, each of which is hereby incorporated by reference and all of which are assigned to the assignee hereof. 
    
    
     FIELD 
     The present invention is directed to methods and apparatus for signaling in wireless communication and, more particularly, to methods and apparatus for using signals for identification, synchronization and/or acquisition. 
     BACKGROUND 
     In a wireless network, e.g., an ad hoc network, in which a network infrastructure does not exist, a terminal has to combat certain challenges in order to set up a communication link with another peer terminal. One challenge is to make the terminals in the vicinity to be synchronized to a common timing and/or frequency reference. A common timing and/or frequency reference is crucial for the terminals to establish communication links. For example, in an ad hoc network, when a terminal just powers up or moves into a new area, the terminal may have to first find out whether another terminal is present in the vicinity before any communication between the two terminals can start. The general solution is to let the terminal transmit and/or receive signals according to certain protocol. However, if the terminals do not have a common timing notation, it is possible that when a first terminal is transmitting a signal and a second terminal is not in the receiving mode, the transmitted signal does not help the second terminal to detect the presence of the first terminal. 
     In view of the above discussion, it should be appreciated that there is a need for new and improved ways for identification, acquisition, and/or synchronization, especially in a wireless system in which the network infrastructure may not be available. 
     SUMMARY 
     Various embodiments are directed to base station methods and apparatus for supporting peer to peer communications. In one exemplary embodiment a base station, which is serving as a network access point for wireless terminals, also transmits a beacon signal conveying information about a peer to peer frequency band. In some such embodiments, the beacon signal conveying information about a peer to peer frequency band is transmitted into the same band being used by the base station for its access node based communications. An exemplary method of operating a base station, comprises: transmitting a beacon signal, said beacon signal including at least one beacon signal burst, said beacon signal conveying information about a peer to peer frequency band, and receiving data from a plurality of wireless terminals using said base station as an access node for communication through said access node. An exemplary base station includes: a beacon signal generation module for generating a beacon signal, said beacon signal including at least one beacon signal burst, said beacon signal burst conveying information about a peer to peer frequency band; a transmitter for transmitting the generated beacon signal, and a receiver for receiving signals including user data signals from a plurality of wireless terminals using said base station as an access node for communication through said access node. 
     Some embodiments are directed to a beacon signal transmission device supporting peer to peer communications and methods of operating a beacon signal transmission device supporting peer to peer communications. One exemplary beacon signal transmission apparatus includes: a beacon signal transmitter for transmitting a sequence of beacon signal bursts each beacon signal burst including at least one beacon symbol, said beacon transmission signal apparatus being a free standing device not including any transmitter used to transmit data to an individual user device. One exemplary method of transmitting beacon signals comprises: operating a beacon signal transmitter to transmit a sequence of beacon signal bursts each beacon signal burst including at least one beacon symbol, wherein said beacon transmission signal apparatus is a free standing device; and wherein said beacon signal transmission apparatus does not include any transmitter used to transmit data to an individual user device. 
     While various embodiments have been discussed in the summary above, it should be appreciated that not necessarily all embodiments include the same features and some of the features described above are not necessary but can be desirable in some embodiments. Numerous additional features, embodiments and benefits are discussed in the detailed description which follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary communications system supporting both access node based communications and peer to peer communications implemented in accordance with various embodiments. 
         FIG. 2  illustrates two exemplary spectrum bands available to be used in a geographic area. 
         FIG. 3  illustrates a ladder diagram of an exemplary method of obtaining and utilizing spectrum information implemented in accordance with various embodiments. 
         FIG. 4  illustrates an example of utilizing timing synchronization information implemented in accordance with various embodiments. 
         FIG. 5  illustrates an exemplary diagram of receiving paging and being in a peer-to-peer or TDD session implemented in accordance with various embodiments. 
         FIG. 6  illustrates a flowchart of an exemplary method of operating a wireless terminal to determine data rates corresponding to potential links with alternative nodes, e.g., a base station and a peer wireless terminal, and selecting a node to communicate with in accordance with various embodiments. 
         FIG. 7  illustrates a ladder diagram of an exemplary method of using beacon and/or broadcast channels to temporarily convert infrastructure spectrum band for non-infrastructure based service implemented in accordance with various embodiments. 
         FIG. 8  illustrates two exemplary ad hoc networks in two geographic areas, implemented in accordance with various embodiments. 
         FIG. 9  illustrates exemplary spectrum bands available to be used in two different geographic areas. 
         FIG. 10  illustrates exemplary system beacon signals transmitted in the ad hoc networks in two different geographic areas. 
         FIG. 11  illustrates an exemplary wireless terminal implemented in accordance with various embodiments. 
         FIG. 12  comprising the combination of  FIG. 12A  and  FIG. 12B  is a drawing of a flowchart of an exemplary method of operating a wireless terminal to communicate with another communications device in accordance with various embodiments. 
         FIG. 13  is a drawing of an exemplary wireless terminal, e.g., mobile node, implemented in accordance with various embodiments. 
         FIG. 14  is a drawing of a flowchart of an exemplary method of operating a wireless terminal which supports both peer to peer communications and communications with a base station in accordance with various embodiments. 
         FIG. 15  is a drawing of an exemplary wireless terminal, e.g., mobile node, implemented in accordance with various embodiments. 
         FIG. 16  is a drawing of a flowchart of an exemplary method of operating a base station in accordance with various embodiments. 
         FIG. 17  is a drawing of an exemplary base station in accordance with various embodiments. 
         FIG. 18  is a drawing of an exemplary beacon signal transmission apparatus in accordance with various embodiments. 
         FIG. 19  is a drawing of a flowchart of an exemplary method of operating a beacon signal transmitter device in accordance with various embodiments. 
         FIG. 20  comprising the combination of  FIG. 20A  and  FIG. 20B  is a drawing of a flowchart of an exemplary method of operating a base station in accordance with various embodiments. 
         FIG. 21  is a drawing of an exemplary base station in accordance with various embodiments. 
         FIG. 22  is a drawing of a flowchart of an exemplary method of operating a wireless device, e.g., a mobile node, in accordance with various embodiments. 
         FIG. 23  is a drawing of an exemplary wireless terminal, e.g., mobile node in accordance with various embodiments. 
         FIG. 24  is a drawing of a flowchart of an exemplary method of operating a mobile communications device in a system including a base station in accordance with various embodiments. 
         FIG. 25  is a drawing of an exemplary wireless terminal, e.g., mobile node, in accordance with various embodiments. 
         FIG. 26  is a drawing of a flowchart of an exemplary method of operating a wireless device, e.g., a mobile node, in accordance with various embodiments. 
         FIG. 27  is a drawing of an exemplary wireless terminal, e.g., mobile node, implemented in accordance with various embodiments. 
         FIG. 28  comprising the combination of  FIG. 28A  and  FIG. 28B  is a drawing of a flowchart of an exemplary communications method in accordance with various embodiments. 
         FIG. 29  is a drawing of an exemplary wireless terminal, e.g., mobile node, in accordance with various embodiments. 
         FIG. 30  is a drawing of an exemplary communications system in accordance with various embodiments. 
         FIG. 31  is a drawing of an exemplary wireless communications system which supports both peer to peer communications and cellular communications in accordance with various embodiments. 
         FIG. 32  is a drawing illustrating exemplary beacon burst time position hopping in accordance with various embodiments. 
         FIG. 33  is a drawing illustrating exemplary beacon burst time position hopping and beacon symbol tone hopping in accordance with various embodiments. 
         FIG. 34  is a drawing illustrating exemplary coordinated timing in a peer to peer communications band in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an exemplary communications system  100  supporting both access node based communications and peer to peer communications implemented in accordance with various embodiments. An infrastructure base station  108  is coupled with a big network, e.g., the Internet, through a network node  110  via a wired link  111 . The base station  108  provides services to the wireless terminals, such as a first wireless terminal  102  and a second wireless terminal  104 , in the geographic area  106  via a wireless spectrum band. The wireless spectrum band is called the infrastructure band. 
     In addition to the infrastructure band, a different spectrum band, referred to as non-infrastructure band may also be, and sometimes is, available to be used by the wireless terminals in the same geographic area. Thus wireless terminals ( 102 ,  104 ) can participate in an ad hoc peer to peer communication session using non-infrastructure band.  FIG. 2  includes drawing  200  which illustrates the notion of the infrastructure band  202  and the non-infrastructure band  204 . The two bands are in some embodiments non-overlapping. In a typical embodiment, the infrastructure band includes a pair of FDD (frequency division duplex) spectrum bands or an unpaired TDD (time division duplex) spectrum band. The non-infrastructure band includes an unpaired spectrum and can be used for ad hoc peer-to-peer communication. In some embodiments, the non-infrastructure band is also used for TDD. In some embodiments, the same infrastructure base station, which provides the service in the infrastructure band, may also provide service in the non-infrastructure band. 
     In an exemplary embodiment, the infrastructure base station transmits a beacon signal in the infrastructure band. The beacon signal is a special signal that occupies a small fraction of the total minimum transmission units in the available spectrum. In some embodiments, a beacon signal includes a sequence of one or more beacon signal bursts, each beacon signal burst including at least one beacon symbol. In some embodiments, the beacon symbols corresponding to a beacon signal occupy a small fraction, e.g., in some embodiments no more than 0.1%, of the total minimum transmission units in the available spectrum air link resource. A minimum transmission unit is the minimum unit of air link resource to use for communication. In some exemplary frequency division multiplexing systems, e.g., some OFDM systems, a minimum transmission unit is a single tone over a symbol transmission period, sometimes referred to as a tone-symbol. In addition, the average transmission power of the beacon symbols of the beacon signal is much higher, e.g., at least 10 dBs or at least 16 dB higher, than the average transmission power of data and control signals per minimum transmission unit when the terminal transmitter is in an ordinary data session. 
     In addition, the infrastructure base station, in some embodiments, uses a broadcast channel, including the beacon signal, to send the system information including the frequency (e.g., carrier) location of the non-infrastructure spectrum band and/or the type of service provided in the band, e.g., TDD (time division duplex) or ad hoc networking. 
       FIG. 3  illustrates an exemplary ladder diagram  300  of an exemplary method of obtaining and utilizing spectrum information implemented by a wireless terminal in accordance with various embodiments. Drawing  300  includes time axis  301 , infrastructure base station  302  and wireless terminal  304 . 
     The wireless terminal  304  knows the frequency location of the infrastructure spectrum band. The wireless terminal  304  first tunes to the infrastructure spectrum band ( 306 ) and searches for the beacon signal ( 308 ) to find the availability of the infrastructure base station. The infrastructure base station  302  transmits beacon signal  310  which is received and detected ( 312 ) by wireless terminal  304 . Once the wireless terminal  304  detects the beacon signal ( 310 ), the wireless terminal  304  synchronizes ( 314 ) itself with the infrastructure base station  302 . The infrastructure base station  302  transmits broadcast signals  316 , in addition to beacon signals  310 . In some embodiments, wireless terminal  304  further receives the broadcast signals  316  and recovers system information from a broadcast channel to obtain the frequency location information of the non-infrastructure spectrum band ( 318 ). The wireless terminal  304 , in various embodiments, derives timing and/or frequency information from at least one of the broadcast channels and/or the beacon signal ( 320 ). The wireless terminal  304  then tunes to the frequency location of the non-infrastructure band to obtain the TDD and/or ad hoc service ( 322 ). The wireless terminal  304  uses the timing and/or frequency information derived in step  320  when the terminal  304  obtains the service in the non-infrastructure band ( 324 ). 
     Unlike the infrastructure band, the non-infrastructure band may not, and sometimes does not, have a natural source from which each of the wireless terminals can derive synchronization information. When each of the wireless terminals use the timing and/or frequency information derived from a common source, i.e., the infrastructure base station in the infrastructure spectrum band, the wireless terminals now have a common timing and/or frequency reference. Advantageously this enables synchronization of the terminals in the non-infrastructure band. To elaborate, drawing  400  of  FIG. 4  illustrates an example of utilizing timing synchronization information obtained from infrastructure signaling in an associated non-infrastructure band. 
     The horizontal axis  401  represents time. The infrastructure base station transmits the beacon signal  402  in the infrastructure band. The beacon signal  402  includes a sequence of beacon signal bursts,  404 ,  406 ,  408 , and so on. Suppose that two wireless terminals derive the timing information from the beacon signal  402 , and then tune to the non-infrastructure band, which is used for peer-to-peer ad hoc network. 
     Either of the two wireless terminals has to be aware of the presence of the other before they can set up a peer-to-peer communication session. In one embodiment, either wireless terminal transmits or receives a user beacon signal burst in the non-infrastructure band in a time interval, which is a function of the timing of the beacon signal bursts sent by the infrastructure base station. 
     For example, in  FIG. 4 , the time interval starts from a time instance that has known time offset  410  from the beginning  412  of a beacon signal burst sent by the infrastructure base station. Either wireless terminal in some embodiments randomly chooses whether to transmit or receive. In the exemplary scenario shown in  FIG. 4 , the first wireless terminal chooses to transmit, as indicated by exemplary user beacon signal burst  414  transmitted into the non-infrastructure spectrum band, while the second wireless terminal chooses to receive. The second wireless terminal controls its receiver on time interval for beacon monitoring in the non-infrastructure spectrum band such as to include interval  416  corresponding to the first wireless terminal&#39;s beacon transmission, and the second wireless terminal detects the user beacon signal sent by the first wireless terminal. The second wireless terminal may, and sometimes does, then start to establish a communication link with the first wireless terminal. However, if both wireless terminals choose to transmit or to receive, then they may not find each other in this time interval. The wireless terminals can probabilistically find each other in subsequent time intervals. 
     Note that in the absence of the common timing reference, the wireless terminals may have to be in the listening mode in a much longer time interval in order to detect a user beacon signal burst. The common timing reference thus helps the wireless terminals to find each other much more rapidly and in a more power efficient manner. 
     In another embodiment, the base station additionally transmits the beacon signal in the second spectrum band, so that if the wireless terminal directly tunes to the second spectrum band, the wireless terminal can derive the desired common timing and/or frequency reference from the beacon signal. 
       FIG. 5  illustrates an exemplary state diagram  500  of receiving paging and being in a peer-to-peer or TDD session implemented in accordance with various embodiments. Operation starts in step  501 , where the wireless terminal is powered on and initialized and then proceeds to step  502 . 
     A wireless terminal and the network paging agent, e.g., a server on the network side, have an agreement on when a page for the wireless terminal, if any, will be sent to the wireless terminal via the infrastructure base station. The wireless terminal sets a timer to monitor potential incoming pages ( 502 ). In a typical paging system, the wireless terminal may go to a power saving mode until the timer expires. In accordance with a novel feature of various exemplary embodiments, the wireless terminal tunes to the non-infrastructure spectrum band and obtains service ( 504 ), e.g., TDD or peer-to-peer communication service. When the timer expires, the wireless terminal tunes to the infrastructure spectrum band and monitors a paging channel ( 506 ). If the terminal is not paged, the wireless terminal may set the timer again for the next page monitoring time ( 502 ). Otherwise, the wireless terminal is being paged, needs to process the received page, and processes the received page ( 508 ). 
     In some embodiments, there is a common time interval during which each of the wireless terminals or a large subset of the wireless terminals using the non-infrastructure spectrum band suspend the sessions in the non-infrastructure spectrum band and check pages in the infrastructure spectrum band. Advantageously, this synchronized suspension of non-infrastructure sessions helps reduce the wastage of resource in the non-infrastructure band. 
       FIG. 6  illustrates a flowchart  600  of an exemplary method of operating a wireless terminal to determine data rates corresponding to potential links with alternative nodes, e.g., a base station and a peer wireless terminal, and selecting a node to communicate with in accordance with various embodiments. 
     A base station transmits a beacon signal. In some embodiments, in the non-infrastructure band, the infrastructure base station transmits a beacon signal, and a wireless terminal also transmits a user beacon signal. Thus, in such an embodiment, a wireless terminal can have its receiver tuned to the non-infrastructure band and receive base station beacon signals and wireless terminal user beacon signals. Different beacon signals, in some embodiments, differentiate from each other by using different beacon tone hopping sequences and/or different timing of beacon bursts. A transmitter, e.g., the base station or the wireless terminal, in some embodiments is also used to transmit data/control channels. In accordance with various embodiments, the transmission power of the beacon signal and/or that of the data/control channels are such that from the received beacon signal or signals, a receiver can predict the signal quality of the data/control channels, and/or compare the signal quality from multiple transmitters. 
     In some embodiments, the transmission power of the base station beacon signal is the same for each base station. In some embodiments, the transmission power of the user beacon signal is the same for each of the wireless terminals transmitting user beacon signals. In some embodiments, the transmission power of base station and user beacons are the same. In some embodiments, the data/control channels are sent at a transmission power, which is a function of the transmission power of the beacon signal. For example, the per minimum transmission unit transmission power of the data channel, at a given coding and modulation rate, is a fixed dB amount, e.g., 10 dBs or 16 dBs, below the transmission power of the beacon signal. 
     With regard to  FIG. 6 , operation of the exemplary method starts in step  601 , where the wireless terminal is powered on and initialized and proceeds to step  602  for each link being considered. In step  602  the wireless terminal receives a beacon signal from a transmitter, e.g., an infrastructure base station transmitter or a wireless terminal transmitter, and then, in step  604  the wireless terminal measures the received power. Operation proceeds from step  604  to step  606 . In step  606 , the wireless terminal then predicts the received power of user data signals, e.g., a data/control traffic channel, assuming that the wireless terminal is receiving the channel from the transmitter, using the known power relationship between the traffic channel and the beacon signal. In step  608 , the wireless terminal further measures the background noise and interference. Then, in step  610 , the wireless terminal predicts the signal quality, e.g., signal-to-noise ratio (SNR) of a data session if the wireless terminal is to set up a session with the device, e.g., base station or wireless terminal, corresponding to the transmitter, and sees whether the signal quality and thus the data rate of the data session are sufficient. In some cases, the wireless terminal may, and sometimes does, receive beacon signals from multiple transmitters. In step  611 , the wireless terminal compares the signal quality from those transmitters considered and selects a proper one with which to communicate, thus selecting the base station or wireless terminal corresponding to the selected transmitter. 
       FIG. 7  illustrates a ladder diagram  700  of an exemplary method of using beacon and/or broadcast channels to temporarily convert infrastructure spectrum band for non-infrastructure based service implemented in accordance with various embodiments. Unlike some of the other embodiments presented, this exemplary embodiment has an infrastructure band but does not need a fixed non-infrastructure band. 
     The vertical axis  702  represents time. The infrastructure base station  704  checks ( 708 ) whether there is any wireless terminal using the normal service provided by the infrastructure base station, such as normal FDD or TDD service. The normal service is referred to as infrastructure based service. If the answer is no, then the infrastructure base station can convert ( 710 ) the infrastructure spectrum band to become a non-infrastructure band, which can be used by non-infrastructure based service, such as peer-to-peer communication service. To do so, the base station sends at least one of a beacon signal ( 712 ) and a non-beacon broadcast signal ( 714 ) to indicate that the infrastructure band has been converted to non-infrastructure band. Upon the reception of that signal, the wireless terminals, e.g., wireless terminal  706 , in the area can start to use non-infrastructure service in the band ( 716 ). 
     At a later time, the infrastructure base station  704  may decide ( 718 ) to return the spectrum band to the infrastructure based service. The infrastructure base station in some embodiments does so because of at least one of the following reasons: 1) the infrastructure base station senses that some wireless terminals may need the infrastructure based service; 2) some timer has expired, in which case the timer is used to control the time duration of the infrastructure spectrum band being used as a non-infrastructure band. To do so, the base station  704  sends at least one of a beacon signal ( 720 ) and a non-beacon broadcast signal ( 722 ) to indicate that the infrastructure band has returned to the infrastructure based service. Upon the reception of that signal, the wireless terminals in the area, e.g., wireless terminal  706 , can cease to use non-infrastructure service in the band ( 724 ). For example, if a wireless terminal has an on-going peer-to-peer communication session, the wireless terminal shall stop or suspend the session. 
       FIG. 8  illustrates in drawing  800  two exemplary ad hoc networks ( 801 ,  851 ) in two geographic areas ( 806 ,  856 ), respectively, implemented in accordance with various embodiments. 
     The ad hoc network  801  in geographic area A  806  includes a number of terminals, such as a first wireless terminal  802  and a second wireless terminal  804 , and a special transmitter  808 , which transmits a system beacon signal in accordance with the exemplary embodiment. The wireless terminals, in some embodiments, use the system beacon signal as a system reference signal. The special transmitter in some embodiments is coupled to a big network, e.g., the Internet, through a network node  810 , e.g., via a wired link. The special transmitter  808 , in some embodiments, is also used to have peer-to-peer sessions with a wireless terminal. Alternatively, in some embodiments the transmitter may be, and sometimes is a standalone unit. 
     The ad hoc network  851  in geographic area B  856  includes a number of terminals, such as a third wireless terminal  852  and a fourth wireless terminal  854 , and a special transmitter  858 , which transmits a system beacon signal in accordance with the exemplary embodiment. The special transmitter in some embodiments is coupled to a big network, e.g., the Internet, through a network node  860 , e.g., via a wired link. 
     In this exemplary embodiment, the spectrum availability is a function of the environment. Here, infrastructure spectrum bands may not exist. For example, drawing  900  of  FIG. 9  shows exemplary spectrum bands available in geographic area A  806  and in geographic area B  856 . Those spectrum bands are non-infrastructure. 
     The horizontal axis  905  represents frequency. The upper portion  901  of the  FIG. 9  shows that there are two spectrum bands,  902  and  904 , available for use in the ad hoc network  801  in geographic area A  806 . The lower portion  903  of  FIG. 9  shows that there are two spectrum bands,  906  and  908 , available for use in the ad hoc network  851  in geographic area B  856 . In the exemplary scenario shown in  FIG. 9 , the spectrum bands  904  and  908  are identical. In other words, part of the spectrum bands available in area A and area B ( 904  and  908 ) are the same, while the rest ( 902  and  906 ) are different. 
     One reason that a different set of spectrum bands are available in a different area is that a spectrum band may have been allocated to other services in some geographic area but can be made available in another area. When a wireless terminal moves into area A or area B, the wireless terminal needs to first figure out which spectrum bands are available for use, so that the wireless terminal does not cause interference or disruption to existing services. 
     To help the wireless terminal to figure out the spectrum availability in a given area, in accordance with a feature of some embodiments, a special transmitter transmits a system beacon signal in each of the spectrum bands that are available for use in the vicinity of the geographical area in which the special transmitter is located. The beacon signal is a special signal that occupies a small fraction of the total minimum transmission units in the available spectrum. In some embodiments, the beacon symbols of the beacon signal occupy no more than 0.1% of the total minimum transmission units in the available spectrum air link resource. A minimum transmission unit is the minimum unit of resource to use for communication. In some exemplary frequency division multiplexing systems, e.g., some OFDM systems, a minimum transmission unit is a single tone over a symbol transmission period, sometimes referred to as an OFDM tone-symbol. In addition, the transmission power of the beacon symbols per minimum transmission unit is much higher, e.g., in some embodiments at least 10 dB higher, than the average transmission power of data and control signals per minimum transmission unit when the transmitter is in an ordinary data session. In some such embodiments, the transmission power of the beacon signal&#39;s beacon symbols per minimum transmission unit is at least 16 dBs higher than the average transmission power of data and control signals per minimum transmission unit when the transmitter is in an ordinary data session. 
     Drawing  1000  of  FIG. 10  illustrates exemplary system beacon signals transmitted in exemplary ad hoc networks ( 801 ,  851 ) in two different geographic areas ( 806 ,  856 ), respectively. The upper portion  1002  illustrates the system beacon signal transmitted by the special transmitter  808  in area A  806  and the lower portion  1004  illustrates the system beacon signal transmitted by the special transmitter  858  in area B  856 . 
     In either the upper or the lower portion ( 1002 ,  1004 ), the horizontal axis  1006  represents frequency and the vertical axis  1008  represents time. 
     Recall from  FIG. 9  that spectrum bands  902  and  904  are available in area A  806 . The upper portion  1002  of  FIG. 10  shows that the special transmitter  808  transmits the system beacon signal burst  1010  including beacon symbol(s)  1012  at time t1  1014  in spectrum band  902 , and transmits the system beacon signal burst  1016  including beacon symbol(s)  1018  at time t2  1020  in spectrum band  904 . The transmitter  808  then repeats the above procedure and transmits the system beacon signal burst  1022  including beacon symbol(s)  1024  at time t3  1026  in spectrum band  902  and transmits the system beacon signal burst  1028  including beacon symbol(s)  1030  at time t4  1032  in spectrum band  904 , and so on. In some embodiments, the beacon signal bursts  1010  and  1022  are identical, e.g., the beacon symbols occupy the same positions in a beacon burst. In some embodiments, the beacon signal bursts  1010 ,  1022  vary, e.g., the positions of the beacon symbols(s) change in accordance with a predetermined hopping sequence being implemented by beacon transmitter  808 . In some the beacon signal bursts  1016  and  1028  are identical. In some embodiments the beacon signal bursts  1016  and  1028  vary, e.g., in accordance with a predetermined hopping sequence being implemented by beacon transmitter  808 . In some embodiments, the beacon signal bursts  1010  and  1016  are similar, e.g., the beacon symbols occupy the same relative positions in the beacon burst. 
     Recall from  FIG. 9  that spectrum bands  906  and  908  are available in area B  856 . The lower portion  1004  of  FIG. 10  shows that the special transmitter  858  transmits the system beacon signal burst  1034  including beacon symbol(s)  1036  at time t5  1038  in spectrum band  906  and transmits the system beacon signal burst  1040  including beacon symbol(s)  1042  at time t6  1044  in spectrum band  908 . The transmitter  858  then repeats the above procedure and transmits the system beacon signal burst  1046  including beacon symbol(s)  1048  at time t7  1050  in spectrum band  906  and transmits the system beacon signal burst  1052  including beacon symbol(s)  1054  at time t8  1056  in spectrum band  908 , and so on. 
     In an exemplary embodiment, at a given time, a special transmitter transmits at most one beacon signal burst in a spectrum band. The special transmitter hops across each of the available spectrum bands, successively from one spectrum band to another, and transmits the beacon signal burst in each band at a given time. For example, in the embodiment shown in  FIG. 10 , times t1  1014 , t2  1020 , t3  1026 , t4  1032  do not overlap with each other. However, it is also possible that in other embodiments the transmitter may, and sometimes does, simultaneously transmit multiple beacon signals, each in a different spectrum band. 
     In the example of drawing  1000  of  FIG. 10 , with respect to the transmitter  808  in area A, t4&gt;t3&gt;t2&gt;t1, and with respect to the transmitter  858  in area B, t8&gt;t7&gt;t6&gt;t5. However, the drawing does not intend to show that a timing relationship between t5 and t4 exists such that t5 is necessarily greater than t4. For example, the range of time including (t1, t2, t3, t4) and the range of time including (t5, t6, t7, t8) may, and sometimes does, at least partially overlap. In some embodiments, the two transmitters ( 808 ,  858 ) operate independently from one another and are not intentionally timing synchronized. In some embodiments, the two transmitters ( 808 ,  858 ) have timing structures which are coordinated, e.g., synchronized with respect to one another. 
       FIG. 11  provides a detailed illustration of an exemplary wireless terminal  1100  implemented in accordance with the present invention. The exemplary terminal  1100 , depicted in  FIG. 11 , is a detailed representation of an apparatus that may be used as any one of terminals  102  and  104  depicted in  FIG. 1 . In the  FIG. 11  embodiment, the wireless terminal  1100  includes a processor  1104 , a wireless communication interface module  1130 , a user input/output interface  1140  and memory  1110  coupled together by bus  1106 . Accordingly, via bus  1106  the various components of the wireless terminal  1100  can exchange information, signals and data. The components  1104 ,  1106 ,  1110 ,  1130 ,  1140  of the wireless terminal  1100  are located inside a housing  1102 . 
     The wireless communication interface  1130  provides a mechanism by which the internal components of the wireless terminal  1100  can send and receive signals to/from external devices and another terminal. The wireless communication interface  1130  includes, e.g., a receiver module  1132  and a transmitter module  1134 , which are connected with a duplexer  1138  with an antenna  1136  used for coupling the wireless terminal  1100  to other terminals, e.g., via wireless communications channels. 
     The exemplary wireless terminal  1100  also includes a user input device  1142 , e.g., keypad, and a user output device  1144 , e.g., display, which are coupled to bus  1106  via the user input/output interface  1140 . Thus, user input/output devices  1142 ,  1144  can exchange information, signals and data with other components of the terminal  1100  via user input/output interface  1140  and bus  1106 . The user input/output interface  1140  and associated devices  1142 ,  1144  provide a mechanism by which a user can operate the wireless terminal  1100  to accomplish various tasks. In particular, the user input device  1142  and user output device  1144  provide the functionality that allows a user to control the wireless terminal  1100  and applications, e.g., modules, programs, routines and/or functions, that execute in the memory  1110  of the wireless terminal  1100 . 
     The processor  1104  under control of various modules, e.g., routines, included in memory  1110  controls operation of the wireless terminal  1100  to perform various signaling and processing. The modules included in memory  1110  are executed on startup or as called by other modules. Modules may exchange data, information, and signals when executed. Modules may also share data and information when executed. In the  FIG. 11  embodiment, the memory  1110  of wireless terminal  1100  includes a signaling/control module  1112  and signaling/control data  1114 . 
     The signaling/control module  1112  controls processing relating to receiving and sending signals, e.g., messages, for management of state information storage, retrieval, and processing. Signaling/control data  1114  includes state information, e.g., parameters, status and/or other information relating to operation of the wireless terminal. In particular, the signaling/control data  1114  includes various configuration information  1116 , e.g., the page monitoring interval, the frequency location of infrastructure spectrum band and non-infrastructure spectrum band, the timing and/or frequency reference information of the beacon signal received from the infrastructure base station, and the power relationship between the beacon signal and the data/control traffic channel. The module  1112  may, and sometimes does, access and/or modify the data  1114 , e.g., update the configuration information  1116 . The module  1112  also includes a module  1113  for receiving system info and timing info on non-infrastructure band from infrastructure base station; module  1115  for using system and timing info in non-infrastructure band; module  1117  for suspending session in non-infrastructure band and monitoring pages in infrastructure band; and module  1119  for predicting signal quality of a data session from received beacon signal power from a transmitter. 
       FIG. 12  comprising the combination of  FIG. 12A  and  FIG. 12B  is a flowchart  1200  of an exemplary method of operating a wireless terminal to communicate with another communications device in accordance with various embodiments. Operation starts in step  1202 , where the wireless terminal is powered on and initialized and proceeds to step  1204 . In step  1204 , the wireless terminal receives a first signal from a first communications band, said first signal being from a first communications device which broadcasts on a recurring basis, said first communications device and said another communications device being different communications devices. Operation proceeds from step  1204  to step  1206 . 
     In step  1206 , the wireless terminal determines, based on the first signal, a first time interval to be used for transmitting a second signal to said another communications device. Then, in step  1208 , the wireless terminal determines based on the first signal a second time interval to be used for receiving signals from devices other than the first communications device. Operation proceeds from step  1208  to step  1210 . 
     In step  1210 , the wireless terminal derives frequency information from the received first signal. Step  1210  includes sub-step  1211  in which the wireless terminal determines a second communications band based on the received first signal. Operation proceeds from step  1210  to step  1212  in which the wireless terminal derives a parameter form the received first signal. Operation proceeds from step  1212  to step  1214  in which the wireless terminal receives another signal from the first communications device, and then in step  1216  the wireless terminal derives a second parameter from another signal received from said first communications device. Operation proceeds from step  1216  to step  1218 . 
     In step  1218 , the wireless terminal determines at least one transmit frequency to be used for transmitting said second signal from the derived frequency information. Operations proceed from step  1218  via connecting node A  1220  to step  1222  of  FIG. 12B . 
     In step  1222 , the wireless terminal generates a second signal as a function of one of device identifier corresponding to said wireless terminal and a user identifier corresponding to a user of said wireless terminal. Then, in step  1224 , the wireless communications device transmits said second signal to said another communications device during said first time interval. Step  1224  includes sub-step  1225  in which the wireless terminal transmits said second signal into said second communications band, which is different from said first communications band. Operation proceeds from step  1224  to step  1226 . 
     In step  1226 , the wireless terminal determines at least one additional transit time as a function of said parameter derived from said first signal. Step  1226  includes sub-step  1227 , in which the wireless terminal uses a time hopping function which uses said parameter and/or said second parameter as input parameters. Operation proceeds from step  1226  to step  1228 . 
     In step  1228 , the wireless terminal establishes a peer to peer communications session with said another device using timing synchronization information derived from said first signal. Then, in step  1230 , the wireless terminal exchanges user data as part of said peer to peer communications session, said user data including at least one of voice data, other audio data, image data, text data and file data, said peer to peer communications session being conducted directly between said wireless terminal and said another device over a direct airlink. 
     In some embodiments the first and second communications bands are non-overlapping. In various embodiments, the first and second communications bands are partially overlapping. In some embodiments, the second signal includes a beacon signal burst, e.g., an OFDM beacon signal burst including at least one beacon symbol. In some embodiments, the second signal is a pseudo noise sequence signal transmitted over the frequency spectrum of the second frequency band. In some embodiments both the first and second signals are OFDM signals. In some embodiments, both the first and second signals are CDMA signals. In some embodiments, both the first and second signals are GSM signals. In some embodiments the first signal is a GSM signal and the second signal is an OFDM signal. In some embodiments, the first signal is a CDMA signal and the second signal is an OFDM signal. In various embodiments, the first signal is a satellite broadcast signal, e.g., a GPS signal, a timing reference signal, a reference signal obtained from a geostationary satellite, a signal from a satellite TV and/or radio broadcast, etc., and the second signal is a terrestrial broadcast signal. The terrestrial broadcast signal is, e.g., from a fixed position base station, from a fixed position special transmitter, e.g., a beacon transmitter, or from a movable transmitter temporarily stationed at a fixed site to provide a reference such as a beacon signal, to be available for use by mobile nodes in the vicinity for a peer to peer network. In some embodiments, the first signal is received from a terrestrial cellular network and the wireless terminal is a mobile handset. 
     One exemplary embodiment will now be described corresponding to flowchart  1200  of  FIG. 12 . The wireless terminal is a first mobile node, and the another communications device is a second mobile node which participates in a peer to peer communications session with the first mobile node. The first communications device is a device such as a base station, special beacon transmitter, satellite, etc., which provides reference information to be used by the wireless terminal and another communications device. The first signal is an OFDM beacon signal burst including at least one beacon symbol, e.g., a high energy tone, transmitted into the first frequency band. The another signal is, e.g., a non-beacon broadcast signal transmitted from the first communications device. Reference timing information is derived from the first signal and used in determining a time for the wireless terminal to receive beacon signals from other wireless terminals, e.g., peers, and in determining a time to transmit its own user beacon signal. The second signal is an OFDM user beacon signal burst including at least one beacon symbol, which is generated as a function of an identifier associated with the wireless terminal or wireless terminal user. From the received first signal the wireless terminal derives the second communications band, which is the communications band to be used for peer to peer communications, which includes transmit frequencies of the user beacon to be generated by the wireless terminal. In this embodiment, the first and second communications bands are non-overlapping. Thus the wireless terminal&#39;s user beacon and peer to peer user data are communicated into the same band, the second communications band. First and second parameters are input control parameters used in a time hopping sequence associated with user beacon signals generated and transmitted by the wireless terminal. For example, one of first and second parameters may provide an indication or notion of time and the other may provide an identifier associated with the transmitter. The wireless terminal time hops the relative position of the beacon burst within a time window from one beacon burst to the next, in accordance with the hopping sequence using the input control parameters. 
       FIG. 13  is a drawing of an exemplary wireless terminal  2300 , e.g., mobile node, implemented in accordance with various embodiments. Exemplary wireless terminal  2300  includes a receiver module  2302 , a transmission module  2304 , a coupling module  2303 , a processor  2306 , user I/O devices  2308 , a power supply module  2310  and memory  2312  coupled together via a bus  2314  over which the various elements may interchange data and information. Memory  2312  includes routines  2316  and data/information  2318 . The processor  2306 , e.g., a CPU, executes the routines and uses data/information  2318  in memory  2312  to control the operation of the wireless terminal  2300  and implement methods. 
     Coupling module  2303 , e.g., a duplex module, couples the receiver module  2302  to antenna  2305  and the transmission module  2304  to antenna  2305 . Power supply module  2312 , which includes a battery  2311 , is used to power up the various components of the wireless terminal. Power is distributed from the power supply module  2310  to the various components ( 2302 ,  2303 ,  2304 ,  2306 ,  2308 ,  2312 ), via a power bus  2309 . User I/O devices  2308  include, e.g., keypad, keyboard, switches, mouse, microphone, speaker, display, etc. User I/O devices  2308  are used for operations including inputting user data, accessing output user data, and controlling at least some functions and operations of the wireless terminal, e.g., initiating a peer to peer communications session. 
     Routines  2316  include a transmission interval timing determination module  2320 , a receive interval timing determination module  2322 , a transmission band control module  2324 , a peer to peer communications band determination module  2326 , a second signal generation module  2328 , an additional transmit time determination module  2330 , a peer to peer communications establishment module  2332 , a peer to peer session management module  2334 , a frequency information recovery module  2336 , and a transmission frequency determination module  2338 . Data/information  2318  includes a received 1st signal  2340 , a determined first time interval  2342 , 1st frequency band information  2358 , a second signal  2344 , a determined 2nd time interval  2346 , 2nd frequency band information  2360 , device identification information  2362 , user identification information  2364 , time hopping function information  2348 , a first time hopping function input parameter  2350 , a second time hopping function input parameter  2352 , a plurality of transmit times corresponding to beacon burst transmissions (transmit time for beacon burst 1  2354 , . . . , transmit time for beacon burst n  2356 ), conveyed frequency information  2366 , and peer to peer session information  2368 . The peer to peer session information  2368  includes peer identification information  2370 , received user data  2372 , user data to be transmitted  2374 , and transmit frequency information  2376 . 
     Receiver module  2302 , e.g., a receiver, receives a first signal from a first communication band, said first signal being from a first communications device which broadcasts on a recurring basis. The first communications device is a different communications device than the communications device with which wireless terminal  2300  has a communications session. Information representing the received 1st signal  2340  is stored in memory  2312 , and 1st frequency band information  2358  identifies the frequency band to which the receiver module is tuned when receiving the 1st signal. The 1st signal is, e.g., a broadcast signal used to obtain a timing reference by the wireless terminal  2300 . Receiver module  2302  also receives signals from other communication devices, e.g., a part of communications sessions such as peer to peer communications sessions. Some of the received signals include user data  2372 . In some embodiments, receiver module  2302  supports a plurality of signaling technologies, e.g., the first signal which is used as a reference may be and sometimes is a different technology than the technology used for peer to peer communications sessions. 
     Transmission module  2304 , e.g., an OFDM transmitter, is used for transmitting a second signal  2344  to a communications device, e.g., a peer wireless terminal, during a determined 1st time interval  2342 . In some embodiments, the second signal  2344  includes a beacon signal burst, e.g., an OFDM beacon signal burst including at least one beacon symbol. Transmission module  2304  also transmits user data  2344 , as part of a peer to peer communications session using transmit frequency information  2376 . 
     Transmission interval timing determination module  2322  determines, based on the received 1st signal  2340 , a first time interval  2342  to be used for transmitting 2nd signal  2344 , e.g., a WT  2300  beacon signal burst, to another communications device, e.g., a peer wireless terminal. Receive interval timing determination module  2322  determines, based on the received 1st signal  2340 , a 2nd time interval  2346  to be used for receiving signals from devices other than the device which transmitted the 1st signal. In some embodiments, the 2nd time interval is a time interval in which wireless terminal  2300  is to receive and monitor for beacon signals from another communications device, e.g., peer wireless terminal. 
     Transmission band control module  2324  controls the wireless terminal  2300  to transmit the 2nd signal  2344 , e.g., WTs  2300 &#39;s beacon signal burst, in a second communications band identified by 2nd frequency band information  2360 . In some embodiments, the 2nd frequency band is different from the 1st frequency band. For example, the wireless terminal  2300  receives a broadcast signal used for timing synchronization in a 1st band and transmits its user beacon in a 2nd frequency band, which is a different band. 
     Peer to peer communications band determination module  2326  determines, prior to transmitting the 2nd signal  2344  the 2nd communication band based on the 1st received communications signal  2340 . Thus peer to peer communications band determination module  2326  determines 2nd frequency band information  2360 . In some embodiments, the 1st and 2nd frequency bands are non-overlapping frequency bands. In some embodiments, the 1st and 2nd frequency bands are partially overlapping frequency bands. 
     Second signal generation module  2328 , generates 2nd signal  2344 , prior to transmitting the second signal as a function of one of a device identifier  2362  corresponding to the wireless terminal and a user identifier  2364  corresponding to a user of wireless terminal  2300 . In some embodiments, second signal generation module  2328  generates signaling including beacon signal bursts, e.g., OFDM beacon signal bursts including at least one beacon symbol. In some embodiments, the second signal is a pseudo noise sequence transmitted over the second frequency band. 
     Additional transmit time determination module  2330  determines at least one additional transmit time as a function of a parameter derived from the 1st signal, e.g., time hopping function input parameter 1  2350 . The additional transmit time determination module  2330  uses a time hopping function which uses parameter  2350  as an input. Time hopping function information  2348  includes, e.g., information defining the time hopping sequence. In some embodiments, the time hopping function uses a second input parameter  2352  derived from another signal received from the communications device which transmitted the 1st broadcast signal. For example, the another signal may be, and sometimes is, a non-beacon broadcast signal communicating the 2nd input parameter. The another signal may be, and sometimes is, another beacon signal burst. 
     Peer to peer communications establishment module  2332  is used to establish a peer to peer communications session with another device, e.g., a peer node, using timing synchronization information derived from the received 1st signal  2340 . 
     Peer to peer session management module  2334  controls the exchange of used data including at least one of voice data, text data, and image data, said peer to peer communications session being conducted directly between the wireless terminal and another device, e.g., peer wireless terminal, over a direct air link. 
     Frequency information recovery module  2336  recovers conveyed frequency information  2366  from the received 1st signal  2340 , prior to transmitting the second signal  2344 , deriving frequency information from the received 1st signal  2340 . For example, the 1st signal conveyed information identifying the 2nd frequency band, the 2nd frequency band to be used by wireless terminal  2300  for transmitting its user beacon signal and for peer to peer user data communications. 
     Transmission frequency determination module  2338  determines at least one transmit frequency to be used for transmitting the second signal from derived frequency information. Information including in  2376  is an output of module  2338 . Transmit information  2376  includes, e.g., frequency band information and/or individual tone identification information. In some embodiments, transmit frequency information identifies OFDM tones used to convey beacon symbols of beacon signal bursts to be transmitted by wireless terminal  2300 . In some such embodiments, beacon symbol tones are tone hopped from one burst to another in a sequence of bursts in accordance with a tone hopping sequence. 
     In some embodiments, both the first and second signals are OFDM signals. In some embodiments, the first signal is a GSM signal and the second signal is an OFDM signal. In some embodiments, the first signal is a CDMA signal and the second signal is an OFDM signal. In some embodiments, the first signal is a satellite broadcast signal and the second signal is a terrestrial broadcast signal. In some embodiments, the first signal is received from a terrestrial cellular network and the wireless terminal is a mobile handset. 
       FIG. 14  is a drawing of a flowchart  1300  of an exemplary method of operating a wireless terminal which supports both peer to peer communications and communications with a base station in accordance with various embodiments. Operation starts in step  1302 , where the wireless terminal is powered on and initialized and proceeds to step  1304 . In step  1304 , the wireless terminal receives a first signal from a first communications band, the first signal being from a base station. Operation proceeds from step  1304  to step  1306 . In step  1306 , the wireless terminal determines the frequency of a second communications band from the first signal, and in step  1308 , the wireless terminal determines an interval of time during which the wireless terminal is to monitor for a second signal in the second communications band, the determination of the time interval being based on information communicated by the first signal, e.g., a time reference communicated. Operation proceeds from step  1308  to step  1310 . 
     In step  1310 , the wireless terminal determines from said first signal link the quality of a first link between said base station and said wireless terminal, and in step  1312 , the wireless terminal predicts a first data throughput to the base station based on the first determined link quality. Step  1312  includes sub-step  1314 , in which the wireless terminal uses maximum transmission power information in the first link quality determination. The maximum transmission power information includes, e.g., at least one of a government restriction on maximum transmission power and device output capability. Operation proceeds from step  1312  to step  1316 . 
     In step  1316 , the wireless terminal monitors during said determined time interval to receive said second signal, and then in step  1318 , the wireless terminal receives said second signal from the second communications band, said second communications band being different from the first communications band, said second signal being from a peer wireless terminal. In some embodiments, the first and second signal each include at least one beacon signal burst. 
     Operation proceeds from step  1318  to step  1320 . In step  1320 , the wireless terminal predicts a second data throughput to the peer wireless terminal based on the second determined link quality. Step  1320  includes sub-step  1322  in which the wireless terminal uses maximum transmission power information in the second link quality determination. The maximum transmission power information includes, e.g., at least one of a government restriction on maximum transmission power and device output capability. Operation proceeds from step  1320  to step  1324 , in which the wireless terminal selects between said first and second links for a communications session based on the determined quality of the first and second links. Step  1324  includes alternative sub-steps  1326 ,  1328 , and  1330 . 
     In alternative sub-step  1326 , the wireless terminal selects the one of the first and second links having a higher data throughput. In alternative sub-step  1328 , the wireless terminal performs the selection as a function of energy required to maintain said first and second links, said selecting including selecting the one of the first and second links satisfying a link quality requirement and also requiring the least amount of energy to maintain. In alternative sub-step  1330 , the wireless terminal performs selection as a function of a least cost routing determination that takes into consideration an economic cost associated with using individual ones of said first and second links. 
       FIG. 15  is a drawing of an exemplary wireless terminal  2400 , e.g., mobile node, implemented in accordance with various embodiments. Exemplary wireless terminal  2400  supports both peer to peer communications and communications via a base station. Exemplary wireless terminal  2400  includes a receiver module  2402 , a transmitter module  2404 , a processor  2406 , user I/O devices  2408 , a memory  2410  coupled together via a bus  2412  over which the various elements may exchange data and information. Memory  2410  includes routines  2414  and data/information  2416 . The processor  2406 , e.g., a CPU, executes the routines  2414  and uses the data/information  2416  in memory  2410  to control the operation of the wireless terminal  2400  and implement methods. 
     Receiver module  2402 , e.g., an OFDM receiver, is coupled to receive antenna  2403  via which the wireless terminal  2400  receives signals from base stations and other wireless terminals. Transmitter module  2404 , e.g., an OFDM transmitter, is coupled to transmit antenna  2405  via which the wireless terminal  2400  transmits signals to base stations and to other wireless terminals. In some embodiments, the same antenna is used for both the receiver and transmitter modules ( 2402 ,  2404 ). 
     User I/O devices  2408  include, e.g., keypad, keyboard, switches, mouse, microphone, speaker, display, etc. User I/O devices  2408  are used for operations including inputting user data, accessing output user data, and controlling at least some functions and operations of the wireless terminal, e.g., initiating a communications session. 
     Routines  2414  include a communications routine  2418  and wireless terminal control routines  2420 . The communications routine  2418  implements the various communications protocols used by the wireless terminal  2400 . The wireless terminal control routines  2420  include a base station link quality determination module  2422 , a peer to peer link quality determination module  2424 , a link selection module  2426 , a beacon burst processing module  2428 , a user data recovery module  2430 , a first data throughput determination module  2432 , a second data throughput determination module  2434 , a power requirement estimation module  2436 , a routing cost determination module  2438 , a frequency band determination module  2440 , a monitor interval determination module  2442 , and a peer to peer signal monitoring module  2444 . 
     Data/information  2416  includes a received 1st signal  2446 , 1st frequency band information  2448 , base station identification information corresponding to the base station which transmitted the 1st signal  2450 , recovered 1st link information  2452 , predicted 1st link data throughput  2454 , estimated amount of energy required to maintain 1st link  2456 , routing cost determination associated with 1st link  2458 , determined 1st link quality  2460 , received 2nd signal  2462 , 2nd frequency band information  2464 , peer wireless terminal identification information corresponding to the peer wireless terminal which transmitted the 2nd signal  2465 , recovered 2nd link information  2466 , predicated 2nd link data throughput  2468 , estimated amount of energy required to maintain 2nd link  2470 , routing cost determination associated with 2nd link  2472 , determined 2nd link quality  2474 , selected link information  2476 , recovered user data  2478 , stored maximum transmission power information  2480 , stored link quality requirement information  2486 , and determined interval of time to monitor for second signals  2488 . Stored maximum transmission power information  2480  includes government restriction information  2482  and device output capability information  2484 . 
     Receiver module  2402  receives a 1st signal from a 1st communication band, the first signal being from a base station. Received 1st signal  2446  includes information representing the 1st signal which was received in the band identified by 1st frequency band information  2448  and was transmitted by the base station identified in information  2450 . Receiver module  2402  also receives a second signal from a second communications band which is different from the first communications band, said second signal being from a peer wireless terminal. Received 2nd signal  2462  includes information representing the 2nd signal which was received in the band identified by 2nd frequency band information  2464  and was transmitted by the peer wireless terminal identified in information  2465 . In some embodiments, the first and second signals each include at least one beacon signal burst, e.g., an OFDM beacon signal burst including at least one beacon symbol. 
     Base station link quality determination module  2422  determines, from the first signal, link quality of a first link between a base station which transmitted the first signal and the wireless terminal  2400 , and determined 1st link quality  2460  is an output of module  2422 . Peer to peer link quality determination module  2424  determines, from the second signal, link quality of a second link between a peer wireless terminal which transmitted the second signal and the wireless terminal  2400 , and determined 2nd link quality  2474  is an output of module  2424 . 
     Link selection module  2426  selects between 1st and 2nd links, for a communications session, based on the determined quality of the first and second links. Determined 1st link quality  2460  and determined 2nd link quality  2474  are inputs to link selection module  2426  and selected link information  2476  is an output of link selection module  2426  which identifies the selected link. 
     Beacon burst processing module  2428  recovers link information from beacon signal bursts (recovered 1st link information  2452  corresponding to 1st signal, recovered 2nd link information  2466  corresponding to 2nd signal). User data recovery module  2430  recovers user data  2478  from non-beacon signals used to communicate user data as part of a communications session. At some times the recovered user data  2478  is from a peer to peer communication session, while at other times the recovered user data is from a communications session in which the user data is relayed through a base station serving as an access node. 
     First data throughput determination module  2432  predicts a first data throughput  2454  to the base station based on the first determined link quality  2460 . Second data throughput determination module  2434  predicts a second data throughput  2468  to the peer wireless terminal based on the second determined link quality  2474 . Link selection module  2426  includes a throughput based selection module for selecting the one of the first and second links having the higher data throughput. First data throughput determination module  2432  uses the stored maximum transmission power information  2480  in predicting the first data throughput  2454 . Second data throughput determination module  2434  uses the stored maximum transmission power information  2480  in predicting the second data throughput  2468 . 
     Power requirement estimation module  2436  estimates the amount of energy required to maintain the 1st and 2nd links (estimated amount of energy required to maintain 1st link  2456 , estimated amount of energy required to maintain 2nd link  2470 ). Link selection module  2426  also performs selection between first and second links for a communications session as a function of energy required to maintain first and second links, said selecting including selecting the one of the 1st and 2nd links satisfying a link quality requirement  2486  and also requiring the least amount of energy to maintain. 
     Routing cost determination module  2438  performs a routing cost determination that takes into consideration economic costs associated with using individual ones of the first and second links. Routing cost determination associated with 1st link  2458  and routing cost determination associated with 2nd link  2472  are outputs of module  2438 . Link selection module  2426  also performs selection between first and second links as a function of least cost routing determination, e.g., using info ( 2458 ,  2472 ) that takes into consideration economic costs associated with individual ones of the first and second links. 
     Frequency band determination module  2440  determines, prior to receiving the second signal, the frequency band of the second signal from the first signal. Thus a base station identifies the frequency band to be used for peer to peer communications in its vicinity. Monitor interval determination module  2442  determines an interval of time during which said wireless terminal  2400  is to monitor for second signals  2488 , e.g., a time interval for wireless terminal  2400  to search for user beacon signals from peer nodes. Peer to peer signal monitoring module  2444  monitors for a signal from a peer wireless terminal during the interval identified to receive second signals, e.g., peer to peer signal monitoring module  2444  monitors for user beacon signal bursts from peer nodes. 
     In some embodiments, the selection module  2426  changes selection criteria and/or re-weights selection criteria as a function of base station identification information, peer identification information, priority information, type of information anticipated to be communicated, wireless terminal  2400  current conditions, and/or latency requirements. For example, selection module  2426 , in some embodiments, heavily weights the selection as a function of energy requirements, when a low battery power condition is detected in wireless terminal  2400 . As another example, selection module  2426  heavily weights the selection based on predicted data throughput when a large amount of time critical data is anticipated to be communicated. 
       FIG. 16  is a drawing of a flowchart  1400  of an exemplary method of operating a base station in accordance with various embodiments. Operation starts in step  1402 , where the base station is powered on and initialized and proceeds to step  1404 . In step  1404 , the base station transmits a beacon signal, said beacon signal including at least one beacon signal burst, said beacon signal conveying information about a peer to peer frequency band, e.g., a peer to peer frequency band which is available for use in the vicinity of the base station. Step  1404  includes sub-step  1406 . In sub-step  1406 , the base station transmits the beacon signal into a first communications band, said beacon signal conveyed information indicating a second frequency band which is used as said peer to peer frequency band, said second frequency band being different from said first frequency band. Operation proceeds from step  1404  to step  1408 . 
     In step  1408 , the base station transmits a second beacon signal into the first communications band, said second beacon signal providing timing synchronization information to a plurality of wireless terminals using the base station as an access node. Operation proceeds from step  1408  to step  1410 . 
     In step  1410 , the base station receives data from at least some of said plurality of wireless terminals using said base station as an access node for communication through said access node, and in step  1412 , the base station transmits user data to at least some of said plurality of wireless terminals using said base station as an access node using the first frequency band. Operation proceeds from step  1412  to step  1404 . 
     In some embodiments, the first frequency band is used in a time division multiplexed manner, and said step of receiving data ( 1410 ) receives data in the first communications band during a first time period and said step of transmitting user data into the first frequency band ( 1412 ) is performed during a second time period which is different from said first time period. In some other embodiments, the base station uses the first frequency band for transmitting signals including said beacon signal, said second beacon signal and said user data signals, while a third communications band is used for receiving user data signals from wireless terminals using the base station as an access point. In some such embodiments, the first, second and third communications bands are different and non-overlapping. In some such embodiments, the base station transmits and receives user data concurrently. 
     In some embodiments, the average base station transmitted power into the second communications band over a 1 minute time period is less than 1/1000 the average base station transmitted power into the first frequency band over the same 1 minute interval. In some such embodiments, the base station does not transmit any power into the second frequency band. 
     In another embodiment, which is a variation of embodiments described with respect to flowchart  1400 , the base station transmits its access node beacon signal and user data into the first frequency band, and transmits a beacon signal for peer to peer communications into the second frequency band, the second frequency band being used for peer to peer communications, but the base station does not transmit any user data into the second frequency band. In some such embodiments, the average base station transmitted power into the second communications band over a 1 minute time period is less than 1/1000 the average base station transmitted power into the first frequency band over the same 1 minute interval. 
     In still another embodiment, which is a variation with respect to flowchart  1400 , the base station transmits both its access node beacon signal and its peer to peer node beacon signal in a first frequency band used for beacon signals. In addition, the base station transmits user data intended for wireless terminals using the base station as an access node into a second frequency band; and the base station refrains from transmitting user data into a third frequency band which is utilized for peer to peer communications, wherein said first, second and third communications bands are non-overlapping. 
       FIG. 17  is a drawing of an exemplary base station  2500  in accordance with various embodiments. Exemplary base station  2500  includes a receiver module  2502 , with associated antenna  2501 , a transmission module  2504 , with associated transmitter antenna  2503 , a processor  2506 , and I/O interface  2508 , and memory  2510  coupled together via a bus  2512  over which the various elements interchange data and information. Memory includes routines  2514  and data/information  2516 . The processor  2506 , e.g., a CPU, executes the routines  2514  and uses the data/information  2516  in memory  2510  to control the operation of the base station  2500  and implement methods, e.g., the method of  FIG. 16 . 
     Routines  2514  include a beacon signal generation module  2518 , a frequency band control module  2520 , a user data transmission control module  2522 , a transmission power control module  2524 , and an access node beacon signal generation module  2526 . Data/information  2516  includes stored peer to peer beacon signal characteristic information  2528 , stored access node beacon signal characteristic information  2534 , peer to peer beacon signal transmission band information  2556 , access node beacon signal transmission band information  2558 , peer to peer communications band information  2560 , base station access node band information  2562 , timing information  2564 , transmission power information  2566 , and wireless terminal data/information  2540  corresponding to wireless terminals using the base station  2500  as an access node. 
     Stored peer to peer beacon signal characteristic information  2528  includes one or more sets of beacon burst information (beacon burst 1 information  2530 , . . . , beacon burst N information  2532 ). Stored access node beacon signal characteristic information  2534  includes one or more sets of beacon burst information (beacon burst 1 information  2536 , . . . , beacon burst N information  2538 ). 
     WTs data/information  2540  corresponding to WTs using the base station as an access node includes a plurality of sets of information (WT 1 data/information  2542 , . . . , WT n data/information  2544 ). WT 1 data/information  2542  includes received user data  2546 , user data to be transmitted  2548 , a base station assigned wireless terminal identifier  2550 , state information  2552 , and communications session information  2554 . 
     Receiver module  2502 , e.g., an OFDM receiver, receives uplink signals from wireless terminals using the base station  2500  as an access node. The received signals include user data signals, e.g., traffic channel signals, from a plurality of wireless terminals using base station  2500  as an access node for communication through the access node. Received user data  2546  corresponding to WT 1 represents user data obtained from received signals from one exemplary wireless terminal using base station  2500  as an access node. 
     Transmitter module  2504 , e.g., an OFDM transmitter, transmits signals to wireless terminals in its vicinity. The transmitted signals include a generated beacon signal intended to support peer to peer communications in its vicinity. The generated beacon signal includes at least one beacon signal burst and conveys information about a peer to peer frequency band. The transmitted signals also include a generated second beacon signal intended to support access node operations, the generated second beacon signal providing timing synchronization information to a plurality of wireless terminals using the base station as an access node. In some embodiments, the generated beacon signal conveying peer to peer frequency band information and the generated second beacon signal communicating access node timing synchronization information are transmitted into the same frequency band. The transmitter  2504  also transmits control data and user data to wireless terminals using the base station as an attachment point. User data to be transmitted  2548 , corresponding to wireless terminal 1, is an example of user data that is transmitted by the base station  2500 , e.g., in downlink traffic channel segments, to a wireless terminal using the base station as an access node. User data includes, e.g., voice, image, text, and/or file data. 
     In some embodiments, receiving data includes receiving data from wireless terminals using the base station as an access node in a first frequency band during a first period of time and transmitting user data into the first frequency band is performed during a second period of time which is different from the first period of time, said frequency band being used in a time division multiplexed manner Timing information  2564 , in some embodiments, identifies first and second periods of time. In various embodiments, the base station does not transmit or receive user data into a second frequency band designated to be used for peer to peer communications. 
     I/O interface  2508  couples the base station  2500  to other network nodes, e.g., other base station, AAA node, home agent nodes, etc. and/or the Internet. I/O interface  2508 , by coupling base station  2500  to a backhaul network allows a wireless terminal using base station  2500  as its point of network attachment to participate in a communications session with another wireless terminal using a different base station as its point of network attachment. 
     Beacon signal generation module  2518  generates a beacon signal, said beacon signal including at least one beacon signal burst, said beacon signal burst conveying information about a peer to peer frequency band, e.g., identifying the peer to peer frequency band. Stored peer to peer beacon signal characteristic information  2528  is used by beacon signal generation module  2518  in generating the beacon signal. In some embodiments, the generated beacon signal by module  2518  conveys peer to peer communications band information  2560 . 
     Frequency band control module  2520  controls transmission of the beacon signal generated by module  2518  into a first communications band, the beacon signal conveying information indicating a second frequency band which is used as the peer to peer frequency band, said second frequency band being different from the first frequency band. In some such embodiments, the first frequency band is the frequency band identified by peer to peer beacon signal transmission band information  2556  and the second frequency band is the frequency band identified by peer to peer communication band information  2560 . 
     User data transmission control module  2522  controls transmission of user data to multiple ones of the plurality of wireless terminals using the base station as an access point using a transmission band identified by the base station access node information. In some embodiments, the band used for transmission of user data to a wireless terminal using the base station as a point of network attachment is the same as the first band which is the band into which the generated beacon signal for peer to peer communications is transmitted. 
     Transmission power control module  2524  controls transmission power into the second frequency band, which is the frequency band used for peer to peer communications, to keep the base station average transmitted power into the second frequency band over a 1 minute time period less than 1/1000 the average transmitted power transmitted into the first frequency band, e.g., the frequency band used for the beacon signal and access node related downlink signaling including user data. In some embodiments, the base station  2500  does not transmit into the second frequency band, which is used for peer to peer communications. 
     Access node beacon signal generation module  2526  uses the data/information  2516  including the access node beacon signal characteristic information  2534  to generate a second beacon signal, the second beacon signal providing timing synchronization information to the plurality of wireless terminals using the base station  2500  as an access node. 
     In some embodiments, (i) the band into which the beacon signal identifying the peer to peer band is transmitted, (ii) the band into which the beacon signal used for wireless terminal timing synchronization with regard to access node operations is transmitted, and (iii) the band used for downlink access node signaling to wireless terminals is the same band. In some such embodiments, the band used for peer to peer communications is a different, non-overlapping band. Thus information  2556 ,  2558 , and  2562 , in some embodiments, identify the same band, while information  2560  identifies a different band. 
       FIG. 18  is a drawing of an exemplary beacon signal transmission apparatus  1500  in accordance with various embodiments. Exemplary beacon signal transmission apparatus  1500  is a free standing device and does not include any transmitter used to transmit user data to an individual user device. Exemplary beacon signal transmission apparatus  1500  includes a receiver module  1502 , a beacon signal transmitter  1504 , a processor  1506 , a solar power supply module  1508 , a power supply module  1510 , a memory  1512  coupled together via a bus  1514  over which the various elements may interchange data and information. The various elements ( 1502 ,  1504 ,  1506 ,  1408 ,  1510 ,  1512 ) are coupled to a power supply by bus  1507 . Memory  1512  includes routines  1516  and data/information  1518 . The processor  1506 , e.g., a CPU, executes the routines  1516  and uses the data/information  1518  in memory  1512  to control the apparatus  1500  and implement methods. 
     Routines  1516  include a beacon signal transmission control module  1520 , a beacon signal generation module  1522 , a receiver control module  1524  and a received broadcast signal information recovery module  1526 . Data/information  1518  includes stored beacon signal characteristic information  1528 , stored beacon signal control information  1530 , received broadcast signal information  1532 , and beacon transmitter identification information  1534 . Stored beacon signal characteristic information  1528  includes one or more sets of beacon burst information (beacon burst 1 information  1536 , . . . , beacon burst N information  1538 ), beacon symbol information  1540 , and power information  1542 . Beacon burst 1 information  1536  includes information identifying beacon transmission units carrying a beacon symbol  1544  and beacon burst duration information  1546 . Stored beacon signal control information  1530  includes beacon burst/frequency band/timing relationship information  1548  and beacon burst/sector/timing relationship information  1550 . Received broadcast signal information  1532  includes timing information  1552 . 
     Receiver module  1502  is coupled to receive antenna  1501  via which the apparatus  1500  receives signals, e.g., a signal used for timing synchronization purposes. In some embodiments, the receiver is one of a GPS, GSM and CDMA receiver. In some embodiments, the receiver is an OFDM receiver. In some embodiments, the receiver module  1502  includes the capability to receive a plurality of different types of signals, and, e.g., depending upon the area of deployment a different type of signal is received and utilized as a reference source. In some such embodiments, the receiver control module  1524  follows a predetermined ordered sequence when determining reference signal search protocol. 
     Receiver  1502 , under the control of receiver control module  1524 , receives a broadcast signal and received broadcast signal information recovery module  1526  recovers received broadcast signal information  1532  from the received broadcast signal including timing information  1552 , e.g., a timing reference. 
     Beacon signal transmitter  1504 , e.g., an OFDM transmitter, is coupled to transmit antennas (sector 1 antenna  1503 , . . . , sector N antenna  1505 ) via which the apparatus  1500  transmits beacon signal bursts which are used to support a peer-peer communications network. Beacon signal transmitter  1504  transmits a sequence of beacon signal bursts, each beacon signal burst including at least one beacon symbol. Beacon signal transmission control module  1520  uses the data/information  1518  in memory  1512  including stored beacon signal control information  1530  and timing information  1552  to control the transmission of beacon burst signals, e.g., controlling beacon signal burst transmission timing as a function of the received broadcast signal which was detected and processed. Beacon signal transmission control module  1520  uses the data/information  1518  including timing information  1552  and beacon burst/frequency band/timing relationship information  1548  to control the beacon transmitter  1504  to transmit beacon signal bursts into different frequency bands at different times. Beacon signal transmission control module  1520  uses the data/information  1518  including timing information  1552  and beacon burst/sector/timing relationship information  1548  to control the beacon transmitter  1504  to transmit beacon signal bursts into sectors at different times. In some such embodiments, the beacon signal transmission control module  1520  controls the beacon signal transmitter  1504  to transmit into at most one sector at a time. 
     Solar power supply module  1508  includes solar cell  1509  for converting solar energy to electrical energy such that apparatus  1500  can be, and sometimes is solar powered. Power supply module  1510  includes battery  1511  for storing energy such that apparatus can be, and sometimes is powered by battery  1511 . Some embodiments include a battery power supply  1511 , but do not include a solar power supply module  1508 , e.g., with the batteries being replaced and/or recharged periodically. In some embodiments, apparatus  1500  is expected to operate for the duration of the battery life and then be discarded or refitted with a replacement battery. In some embodiments, the beacons signal transmission apparatus  1500  is independently powered, e.g., operating from a portable gasoline, diesel, kerosene, propane, natural gas, and/or hydrogen based, generator and/or fuel cell. Embodiments using solar, battery and/or other independent energy sources are advantageous in remote sites, where a local power grid may be unavailable and/or in areas where a power grid is unreliable. In various embodiments, beacon signal transmission power is coupled to a power grid for receiving power. 
     Beacon signal generation module  1522  uses the data/information including stored beacons signal characteristic information  1528  and/or beacon transmitter identification information  1534  to generate a sequence of beacon signal bursts, each beacon signal bust including at least one beacon symbol, the beacon signal burst intended to be used to support peer to peer communications. Information identifying beacon transmission units carrying a beacon symbol  1544  include, e.g., information identifying a subset of OFDM tone-symbols designated to carry a high power beacon symbol in a set of OFDM tone-symbols of beacon burst 1. Beacon burst symbol information  1540  includes information defining a beacon symbol, e.g., a modulation symbol value, while power information  1542  includes transmission power level information associated with the beacon signal. In some embodiments, each of the beacon symbols is controlled to be transmitted at the same transmission power level. In some embodiments, each of the beacon symbols corresponding to a given sector and a given frequency band are controlled to be transmitted at the same transmission power level, with at least some beacon symbols corresponding to different sectors and/or frequency bands are transmitted at different power levels. 
       FIG. 19  is a drawing of a flowchart  2600  of an exemplary method of operating a beacon signal transmitter device in accordance with various embodiments. The beacon signal transmitter device is, e.g., a free standing device, and the beacon signal transmitter device does not include any transmitter used to transmit user data to an individual user device, e.g., wireless terminal. In various embodiments, the beacon signal transmitter device includes an OFDM beacon signal transmitter for transmitting OFDM beacon signal bursts, each beacon signal burst including at least one relatively high power OFDM beacon symbol, e.g., with respect to the transmission power levels of data symbols transmitted by wireless terminals communicating in a peer to peer communications session in the local region being serviced by the beacon signal transmitter device. 
     Operation starts in step  2602 , where the beacon signal transmitter device is powered on and initialized. Operation proceeds from start step  2602  and proceeds to step  2604 . In step  2604 , the beacon signal transmitter device scans for different types of broadcast signals that can be used as timing reference signals. In some embodiments, the scanning is performed based on a predetermined sequence based on at least some geographic location information. Then, in step  2606 , the beacon signal transmitter device receives a broadcast signal, and in step  2608  determines a signal burst transmission timing as a function of the received broadcast signal. In some embodiments, the receiver is a receiver which includes at least one of a GPS receiver, a GSM receiver, and a CDMA receiver. Operation proceeds from step  2608  to step  2610 . 
     In step  2610 , the beacon signal transmitter device is operated to transmit a sequence of beacon signal bursts, each beacon signal burst including at least one beacon symbol. Step  2610  includes sub-steps  2612 ,  2614 ,  2616 ,  2618 ,  2620 , and  2622 . In sub-step  2612 , the beacon signal transmitter device&#39;s transmitter is powered from one of: a battery power source, a solar power source, and a power source which is independent of a commercial power grid. 
     In sub-step  2614 , the beacon signal transmitter device compares current timing information to predetermined schedule information. Operation proceeds from 1st-step  2614  to sub-step  2616 , in which the beacon signal transmitter device determines if it is time to transmit a beacon signal burst or bursts. If it is determined in sub-step  2616 , that it is not time to transmit a beacon signal burst, then operation proceeds back to step  2614  for additional comparison of timing information. However, if it is determined in sub-step  2616 , that the beacon signal transmitter device is scheduled to transmit a beacon signal burst(s), then operation proceeds to sub-step  2618 , where the device determines the frequency band or bands into which the beacon signal burst(s) are to be transmitted. Operation proceeds from sub-step  2618  to sub-step  2620 , in which the device determines the sector or sectors into which the beacon signal burst or bursts are to be transmitted. Then, in sub-step  2622 , the beacon signal transmitter device transmits the scheduled beacon signal burst or bursts into the determined frequency band or bands into the determined sector or sectors. Operation proceeds from sub-step  2622  back to sub-step  2614  for additional time comparisons. 
     In various embodiments, the beacon signal transmitter device uses stored control information to determine a plurality of frequency bands into which the beacon signal bursts are to be transmitted and the time at which the transmission of the beacon signal bursts are to occur. In some embodiments, the beacon signal transmitter device controls its transmitter to transmit beacon signal burst into different frequency bands at different times. In some embodiments, the beacon signal transmitter device controls its transmitter to use a multi-sector antenna and to transmit beacon signal bursts into different sectors at different times. In one such embodiment, the beacon signal transmitter device controls its transmitter to transmit into at most one sector at a time. In some embodiments, the beacon signal transmitter device controls its transmitter to transmit into at most one frequency band at a time. 
     In various embodiments, the beacon signal transmitter controls its transmitter to transmit into multiple frequency bands in each of multiple sectors of a cell. In some embodiments, the beacon signal transmitter is controlled to transmit into at most one frequency band of one sector at a given time at which beacon signal bursts are transmitted. 
     In some embodiments, described with respect to flowchart  2600 , the beacon signal transmitter device obtains an external reference from a received broadcast signal. In some embodiments, the beacon signal transmitter does not include a receiver and does not receive a reference signal. For example, the beacon signal transmitter device transmits its beacon signal bursts in accordance with stored schedule information corresponding to a recurring schedule, and the beacon signal transmitter device&#39;s timing is free running and not coordinated with any other beacon signal transmitter device. 
       FIG. 20  is a drawing of a flowchart  1600  of an exemplary method of operating a base station in accordance with various embodiments. The exemplary base station switches between infrastructure spectrum use and peer to spectrum use. Thus at different times spectrum, e.g., a frequency band, in the vicinity of the base station is used for different purposes. Operation starts in step  1602 , where the base station is powered on and initialized and proceeds to step  1604  and connecting nodes A  1606 , B  1608 , C  1610  and D  1612 . 
     In step  1604 , the base station sets its mode to a second mode, e.g., an access mode operation mode with respect to a first frequency band. In this particular exemplary embodiment, the access mode with respect to the first frequency band is the start-up default mode. In other embodiments, the peer to peer mode of operation is the start-up default mode, and the base station starts up in a mode in which the first frequency band is designated to be used for peer to peer communications. Operation proceeds from step  1604  to steps  1614  and step  1616 . 
     In step  1614 , the base station transmits a second broadcast signal during a second period of time conveying information that a first frequency band is be used as a non-peer to peer frequency band during a second period of time. In step  1616 , during the second period of time, the base station operates as a network access point to relay information received over an airlink from a first communications device via a communications network to a second communications device. Operation proceeds from step  1614  and step  1616  to step  1618 . 
     Returning to connecting node A  1606 , operation proceeds via connecting node A  1606  to step  1628 , where the base station monitors communications activity level during the second mode of operation. Operation proceeds from step  1628  to step  1630 , in which the base station checks whether the activity is below a predetermined threshold. If the level of activity is below a predetermined threshold, then operation proceeds to step  1632 , where the activity level information  1636  is updated to indicate a low level of activity, e.g., corresponding to a level in which the mode is to be switched in response to the determined low level. If the activity level is not below the threshold, then operation proceeds from step  1630  to step  1634  in which the base station updates the activity level information  1636  to indicate that the threshold is above the mode switch threshold, e.g., the base station should remain in the second mode based on the current level of activity. In some embodiments, the predetermined threshold corresponds to one wireless terminal currently using the base station as a network attachment point. In some embodiments, the predetermined threshold corresponds to one wireless terminal currently using the base station as a network attachment point and communicating at least some user data via the base station from and/or to that wireless terminal. Operation proceeds from step  1632  or step  1634  to step  1628  for additional monitoring. 
     Returning to connecting node B  1608 , operation proceeds via connecting node B  1608  to step  1638 , where the base station monitors for signals from wireless terminals, while in a first mode of operation, indicating that a wireless terminal is seeking to use the base station as an access point. Then, in step  1640 , the base station checks if a signal was detected in step  1638 . If a signal was detected operation proceeds from step  1640  to step  1642 , where the base station updates the desired activity level information  1644 . Operation proceeds from step  1642  to step  1638  for additional monitoring. If a signal was not detected in step  1640 , operation proceeds from step  1640  to step  1638  for additional monitoring. 
     Returning to connecting node C  1610 , the operation proceeds via connecting node C  1610  to step  1646 , where the base station monitors for an override condition to occur. Step  1646  includes sub-step  1648  and sub-step  1650 . In sub-step  1648 , the base station monitors for receipt of a control signal indicating preemption of the first frequency band, e.g., by a government organization. In sub-step  1650 , the base station monitors for receipt of a control signal indicating of preemption of the first frequency band, e.g., by a high priority user. Operation proceeds from step  1646  to step  1652 . 
     In step  1652 , the base station determines if a condition used to override the second mode of operation has occurred. If a condition has occurred, then operation proceeds from step  1652  to step  1654 , where the base station updates the mode override information  1656 ; otherwise operation proceeds from step  1652  to step  1646  for additional monitoring. Operation proceeds from step  1654  to step  1646  for additional monitoring. 
     Returning to connecting node D  1612 , operation proceeds via connecting node D  1612  to step  1658 , where the base station monitors for a mode change signal from a wireless terminal indicating that the wireless terminal has the authority to alter the current mode of base station operation. In some embodiments, the information indicating that the wireless terminal has the authority to alter the current mode of base station operation is one of a wireless terminal identifier, priority level indicated and a wireless terminal user identifier. Operation proceeds from step  1658  to step  1660 , in which the base station determines whether such a mode change signal has occurred. If an authorized mode change signal has been detected, operation proceeds from step  1660  to step  1662 , where the base station updates the authorized mode change information  1664 ; otherwise operation proceeds from step  1660  to step  1658  for additional monitoring. Operation proceeds from step  1662  back to step  1658  for additional monitoring. 
     Returning to step  1618 , in step  1618 , the base station makes a mode change determination as a function of the activity level information  1636 , authorized mode change information  1664 , and/or mode override information  1656 . If the determination in step  1618 , is that the mode should change, then operation proceeds to step  1620 , where the base station switches from a second mode of operation to a first mode of operation in which the base station ceases to operate as an access node; otherwise operation proceeds from step  1618  to the input of steps  1614  and  1616  and operation continues in the second mode. 
     From step  1620 , operation proceeds to step  1622 , where the base station transmits a first broadcast signal during a first period of time, the first broadcast signal conveying information indicating that the first frequency band is to be used as a peer to peer frequency band. Operation proceeds from step  1622  to step  1624 , where the base station determines whether the mode should be changed. The base station uses the desired activity level information  1642  and/or authorized mode change information  1664  in deciding whether to implement a mode change. If the decision of step  1624  is that the mode should be changed, then operation proceeds to step  1626 , where the base station switches from the first mode of operation to the second mode of operation in which the base station operates as an access node; otherwise operation proceeds from step  1624  to the input of step  1622 , and the base station continues to operate in the first mode, e.g., a mode supporting use of the first frequency band as a peer to peer band. Operation proceeds from step  1626  to the inputs of steps  1614  and step  1616 , where the base station operates in the second mode as an access node. 
       FIG. 21  is a drawing of an exemplary base station  2700  in accordance with various embodiments. Exemplary base station  2700  includes the capability to control reallocation of frequency spectrum between infrastructure use, e.g., with the communications being directed through the base station  2700  functioning as an access node, and peer to peer spectrum use in which direct communications links between peer wireless terminals are used. 
     Exemplary base station  2700  includes a receiver module  2702 , a transmission module  2704 , a processor  2706 , an I/O interface  2708 , and memory  2710  coupled together via a bus  2712  over which the various elements may interchange data and information. Memory  2710  includes routines  2714  and data/information  2716 . The processor  2706 , e.g., a CPU, executes the routines  2714  and uses the data/information  2716  in memory  2710  to control the operation of the base station and implement methods, e.g., the method of  FIG. 20 . 
     Receiver module  2702 , e.g., an OFDM receiver, is coupled to receive antenna  2701  via which the base station  2700  receives signals from wireless terminal, e.g., when the base station is functioning as an access node. Transmission module  2704 , e.g., an OFDM transmitter, is coupled to transmit antenna  2703 , via which the base station  2700  transmits signals to wireless terminals. The transmitted signals include broadcast signals such as beacon signals used to identify whether a frequency spectrum is to be used in an access mode of operation or in a peer to peer communications session mode of operation. When the base station  2700  is using spectrum in an access mode of operation, the transmitter  2704  also transmits downlink signals, e.g., pilot channel signals, control channel signals and user data signals, e.g., traffic channel signals to wireless terminals using the base station  2700  as a point of network attachment. 
     Transmission module  2704  transmits a 1st broadcast signal during a 1st period of time, the first broadcast signal conveying information indicating that a first frequency band is to be used as a peer to peer frequency band, and transmits a second broadcast signal during a second period of time, the second broadcast signal conveying information indicating that the first frequency band is to be used as a non-peer to frequency band during the second period of time. In some embodiments, the 1st and 2nd broadcast signals are beacon signals, e.g., OFDM beacon signals. 1st broadcast signal is generated by base station  2700  based upon 1st broadcast signal information  2730 , e.g., information identifying beacon symbols in beacon signal bursts and timing beacon burst timing information representing the 1st broadcast signal, conveys peer to peer frequency band information. 2nd broadcast signal is generated by base station  2700  based upon 2nd broadcast signal information  2732 , e.g., information identifying beacon symbols in beacon signal bursts and timing beacon burst timing information representing the 2nd broadcast signal, and conveys non-peer to peer frequency band information  2744 . Thus a wireless terminal can monitor for the presence of 1st and 2nd broadcast signals from base station  2700  and depending upon which one is detected, determine how the first frequency band is currently being used. 
     I/O interface  2708  couples the base station  2700  to other network nodes, e.g., other base station, AAA node, home agent nodes, etc. and/or the Internet. I/O interface  2708 , by coupling base station  2700  to a backhaul network allows a wireless terminal using base station  2700  as its point of network attachment to participate in a communications session with another wireless terminal using a different base station as its point of network attachment. 
     Routines  2714  include a transmitter control module  2718 , a routing module  2720 , a mode control module  2722 , a monitoring module  2724 , a security module  2726 , and an activity level monitoring module  2728 . The mode control module  2722  includes an override module  2723 . Data/information  2716  includes 1st broadcast signal information  2730 , 2nd broadcast signal information  2732 , transmission timing information  2734 , mode of operation information  2736 , detected access request signal information  2738 , security information  2740 , peer to peer frequency band information  2742 , non-peer to peer frequency band information  2744 , network topology information  2746 , current network routing information  2748 , determined current level of communications activity information  2750  and activity level based switching criteria  2756 . The determined current level of communications activity information  2750  includes a determined bandwidth utilization level  2752  and a determined number of active wireless terminal users  2754 . Activity level based switching criteria  2756  includes a bandwidth utilization switching threshold  2758  and a number of active terminals switching threshold  2760 . 
     Transmitter control module  2718  controls the transmission module  2704  to transmit said first and second broadcast signals during said first and second periods of time, respectively, said first and second periods of time being non-overlapping. Routing module  2720 , which is used during the second period of time, routes user data received over an airlink from a first communications device to a second communications device via a communications network coupled to said base station. Routing module  2720  uses network topology information  2746  and current network routing information  2748 , e.g., information identifying congestion locations, failed nodes, alternative routing costs, delay consideration information, etc., to determined user data routing. 
     Mode control module switches between first and second modes of operation. The current mode of operation into which the base station has been switched is indicated by mode of operation information  2736 . The first mode of operation corresponds to a mode during the first periods of time in which the first frequency band is being utilized as a peer to peer frequency band, while the second mode of operation is a mode of operation in which the first frequency band is being utilized for non peer to peer communications with the base station  2700  serving as an access node. When the mode control module  2722  switches from the second mode of operation to the first mode of operation the mode control module  2722  stops the base station  2700  from acting as an access node, e.g., with regard to the first frequency band in the region into which the 1st broadcast signal transmission is directed. 
     Monitoring module  2724  monitors for and detects signals from wireless terminals that are seeking to use the base station  2700  as an access node. For example, the base station  2700  may be currently in the first mode of operation in which the first band is being used for peer to peer communications; however, a wireless terminal may desire that the base station reallocate the spectrum to access node operation, and send an access request signal to the base station which is detected and recovered by monitoring module  2724 . The recovered information is, e.g., detected access request signal information. In some embodiments, the detected access request signal information includes information indicating that the wireless terminal making the request has the authority to command the requested change. For example, the information indicating that the wireless terminal has the authority to alter the current mode of base station operation is, in some embodiments communicated by one of a wireless terminal identifier, a priority level indicated, and a wireless terminal user identifier. Security information  2740  includes information utilized in making authorization evaluations, e.g., lists of authorized users, wireless terminal, and/or priority level interpretation information. The base station  2700  considers the request in making a decision as to whether or not to switch modes. For example, the base station switches from the first mode of operation to the second mode of operation in response to a signal received from a wireless terminal indicating that the wireless terminal is seeking to use the base station as an access node. 
     Security module  2726 , using security information  2740 , determines that a signal requesting a mode change is from a wireless terminal or user having the authority to command the requested mode change. 
     Activity level monitoring module  2728  determines the level of communications activity  2750  while the base station is in the second mode of operation functioning as an access node. The mode control module  2722  is responsive to a low activity level, which it uses to initiate a switch from the second mode of operation to the first mode of operation. In some embodiments, at some times, a low level of activity is indicated by determined bandwidth utilization level  2752  being below a predetermined threshold, the bandwidth utilization switching threshold  2758 . In some embodiments, at some times, a low level of activity is indicated by determined number of active wireless terminals  2754  being below a predetermined threshold, the number of active terminals switching threshold  2760 . In various embodiments, the determined number of active wireless terminals  2754  indicates the number of wireless terminals currently using the base station as an access point. In some embodiments, the number of active terminals switching threshold is set to 1. 
     Override module  2723  detects when a current mode override condition occurs. The current mode override condition is, e.g., the receipt of a control signal indicating preemption of the first frequency band. The preemption can be, and sometimes is, by a government organization. Alternatively, the preemption can be, and sometimes is, by a high priority user. The control signal can be communicated over an airlink and received via receive module  2702  or communicated over the backhaul network and received via I/O interface  2708 . 
       FIG. 22  is a drawing of a flowchart  1700  of an exemplary method of operating a wireless device, e.g., a mobile node, in accordance with various embodiments. Operation starts in step  1702 , where the wireless device is powered on and initialized and proceeds to step  1704 , where the wireless device establishes a communications link with a base station. Then, in step  1706 , the wireless device monitors for broadcast signals from the base station while maintaining the link. Operation proceeds from step  1706  to step  1708 . 
     In step  1708 , the wireless device checks whether a predetermined change in at least one of said broadcast signals indicative of a change in communications mode of operation from a cellular mode to a peer to peer mode has been detected. In some embodiments, the change in at least one of said broadcast signals is a change in a beacon signal, e.g., a change in an OFDM beacon signal being transmitted by the base station. In some such embodiments, the change includes a change in information communicated by the beacon signal. In various embodiments, the information communicated by the beacon signal indicates a peer to peer mode of frequency spectrum use after said change. If in step  1708  the wireless device detected a change in a broadcast signal indicative of a change in communications mode of operation from a cellular mode to a peer to peer mode, then operation proceeds from step  1708  to step  1710 ; otherwise operation proceeds from step  1708  to step  1706  for additional monitoring. 
     In step  1710 , the wireless device, in response to detecting the change, ceases to maintain the link. Step  1710  includes sub-step  1710  in which the wireless device terminates control signaling used to maintain said link. Operation proceeds from step  1710  to step  1714 , in which the wireless device starts to maintain transmission silence. Then, in step  1716 , the wireless device ceases communication with the base station in the frequency spectrum previously used by the communications link. Operation proceeds from step  1716  to step  1720 . In step  1720 , the wireless device switches from a cellular mode of operation to a peer to peer mode of operation. Operation proceeds from step  1720  to step  1722 . 
     In step  1722 , the wireless device checks for a peer to peer session initiation event. For example, a session initiation event is, e.g., a signal from a peer requesting session establishment, or a decision by the wireless device to attempt to establish a peer session with another wireless terminal detected or known to be in the region. In response to a session initiation event, operation proceeds form step  1722  to step  1726 , where the wireless device establishes a peer to peer communications session with another wireless terminal. If a peer to peer session initiation event was not detected, then operation proceeds from step  1722  to step  1724 , where the wireless device continues to maintain transmission silence. In some other embodiments, while in the peer to peer mode, the wireless device transmits some broadcast signals, e.g., some user beacon signals, irrespective of whether or not the wireless terminal is in a communications session. 
     Operation proceeds form step  1724  or step  1726  to step  1728 , where the wireless device continues to monitor for signals from the base station, e.g., broadcast signals such as beacon signals conveying spectrum usage information. Operation proceeds from step  1728  to step  1730 . In step  1730 , the wireless device determines whether a broadcast signal indicating a cellular mode of operation was detected. If such a signal was detected, operation proceeds from step  1730  to step  1732 ; otherwise, operation proceeds from step  1730  to step  1728  for additional monitoring. 
     In step  1732 , the wireless device terminates the peer to peer communications session with said another terminal, if such a session was established. Then, in step  1734 , the wireless device re-establishes a link with the base station, e.g., with the wireless device having remained in the coverage area corresponding to the base station between the time the link ceased to be maintained and the time the link was re-established. 
       FIG. 23  is a drawing of an exemplary wireless terminal  2800 , e.g., mobile node in accordance with various embodiments. Exemplary wireless terminal  2800  can, and sometimes does, switch between a cellular operation mode and a peer to peer operational mode in response to received broadcast signals, e.g., beacon signals. Wireless terminal  2800  includes a receiver module  2802 , a transmitter module  2804 , a processor  2806 , user I/O devices  2808 , and memory  2810  coupled together via a bus  2412  over which the various elements may interchange data and information. Memory  2810  includes routines  2814  and data/information  2816 . The processor  2806 , e.g., a CPU, executes the routines  2814  and uses the data/information  2816  in memory  2810  to control the operation of the wireless terminal  2800  and implement methods, e.g., a method in accordance with  FIG. 22 . 
     Routines  2814  include a communications routine  2818  and wireless terminal control routines  2820 . The communications routine  2818  implements the various communications protocols used by the wireless terminal  2800 . Wireless terminal control routines  2820  include a link establishment module  2822 , a broadcast signal monitoring module  2824 , a mode determination module  2826 , a mode control module  2828 , a control signaling module  2830 , a link re-establishment module  2832 , and a peer to peer communications establishment module  2834 . Mode control module  2828  includes switching module  2829 . 
     Data/information  2816  includes detected broadcast signal information  2836 , detected change in broadcast signal information  2840 , determined mode of operation communicated by broadcast signaling  2842 , spectrum usage information  2848 , wireless terminal current mode of operation information  2844 , and generated control signals  2846 . Data/information  2816  also includes broadcast signals&#39; identification information  2850  and broadcast signals&#39; information recovery information  2852 . The broadcast signals&#39; identification information  2850  includes beacon symbol energy level detection information  2854 , and beacon symbol pattern information  2856 . Broadcast signals&#39; information recovery information  2852  includes beacon signal to mode mapping information  2858  and beacon signal to spectrum usage mapping information  2860 . 
     Receiver module  2802 , e.g., an OFDM receiver, is coupled to receive antenna  2803  via which the wireless terminal receives signals. Receiver module  2802  receives broadcast signals from base stations. The broadcast signals include, e.g., beacon signaling used to communicate a current mode of spectrum usage. When the base station is functioning as an access node, the wireless terminal receiver  2802  can, and sometimes does, receive control signals and user data signals from the base station in the spectrum. When the spectrum is being utilized for peer to peer communications, the wireless terminal receiver  2802  can, and sometimes does, receive signals directly from a peer wireless terminal, e.g., user beacon signals, peer to peer session establishment signals, and user data signals as part of a peer to peer communication session. 
     Transmitter module  2804 , e.g., an OFDM transmitter, is coupled to transmit antenna  2805  via which the wireless terminal  2800  transmits signals. In some embodiments, the same antenna is used by the transmitter and receiver. Transmitted signals include, e.g., access node based session establishment signals, peer to peer node session establishment signals, control signal to an access node as part of maintaining a link with the access node, user data signals to an access node, and user data signals to a peer node as part of a peer to peer communication session. 
     User I/O devices  2808  include, e.g., keypad, keyboard, switches, mouse, microphone, speaker, display, etc. User I/O devices  2808  are used for operations including inputting user data, accessing output user data, and controlling at least some functions and operations of the wireless terminal, e.g., initiating a communications session. 
     Link establishment module  2822  establishes a communications link with a base station. Broadcast signal monitoring module  2824  monitors to detect broadcast signals from base stations. Mode determination module  2826  determines a communications mode of operation from at least one broadcast signal from a base station detected by the monitoring of module  2824 . In various embodiments, the broadcast signal from the base station used by the mode determination module  2826  for its determination is a beacon signal. In some embodiments, the mode determination is based on a change in a beacon signal, e.g., as indicated in detected change in broadcast signal information  2840 . In some such embodiments, the change indicates a change in information communicated by the beacon signal. For example, the information communicated by the beacon signal indicates a peer to peer frequency spectrum use after the change, while the beacon signal information before the change indicates a cellular mode usage of the spectrum. As another example, the information communicated by the beacon signal indicates a cellular mode spectrum use after the change, while the beacon signal information before the change indicates a peer to peer mode usage of the spectrum. 
     Mode control module  2828  controls the wireless terminal  2800  to operate in the mode determined by the mode determination module  2826 . The mode control module  2828  can, and sometimes does, drop an established link with a base station when the mode determination module  2826  indicates a change in a communication mode of operation from a cellular mode to a peer to peer mode of operation. Switching module  2829  switches the wireless terminal  2800  from a cellular mode of operation to a peer to peer mode of operation in response to detecting a predetermined change in at least one of the broadcast signals. Wireless terminal current mode of operation  2844  indicates the current mode of wireless terminal operation, e.g., cellular mode or peer to peer mode, into which the wireless terminal has been switched. 
     Control signaling module  2830  generates control signals  2846  to maintain an established link with a base station. Generated control signals  2846  include, e.g., power control signals, timing control signals, control channel report signals such as SNR reports, etc. When the mode control module  2828  drops an established link with a base station, the mode control module  2828  controls the control signaling module  2830  to stop generating control signals used to maintain the link. 
     Link re-establishment module  2832  re-establishes a link with a base station in response to detecting a broadcast signal indicating a cellular mode of operation. Peer to peer communications establishment module  2834  is used to establish a peer to peer communications session with another wireless terminal, e.g., during at least a portion of the time between which said link is ceased to be maintained with the base station and the link is re-established with the base station. 
     Detected broadcast signal information  2836 , e.g., detected beacon signal information is an output of broadcast signal monitoring module  2824 . Broadcast signal monitoring module  2824  uses the data/information  2816  including the broadcast signals&#39; identification information  2850  to detect beacon signals. Beacon symbol energy level detection information  2854  includes energy level criteria used for identifying beacon symbols from among a plurality of received signals. For example, a beacon signal includes a beacon signal burst including at least a beacon symbol and the beacon symbol is transmitted at a relatively high energy level with respect to other signals transmitted by the base station, facilitating easy detection by a wireless terminal. Beacon symbol pattern information  2856  includes information identifying sets of beacon symbols within a set of beacon symbol transmission units. For example, a particular pattern of beacon symbols may, and sometimes does represent a particular beacon signal. 
     Mode determination module  2826  uses the data/information  2816  including the broadcast signals&#39; information recovery information  2852  to determine a mode of operation being communicated by the broadcast signal  2842 , e.g., one of a cellular mode and a peer to peer mode, and spectrum usage information  2848 , e.g. one of a cellular mode spectrum allocation and a peer to peer mode spectrum allocation. In some embodiments the cellular mode spectrum usage information further identifies one of a time division duplex use of spectrum and a frequency division duplex use of spectrum. For example, the base station when functioning as an access node may operate in a TDD manner in which the spectrum is alternately used for downlink and uplink, or the base station may operate using two distinct bands for uplink and downlink which allow simultaneous uplink and downlink signaling. 
       FIG. 24  is a drawing of a flowchart  1800  of an exemplary method of operating a mobile communications device in a system including a base station in accordance with various embodiments. Operation starts in step  1802 , where the mobile communications device is powered on and initialized and proceeds to step  1804 . In step  1804 , the mobile communications device determines a base station mode of operation, the base station mode of operation being one of an access mode of operation in which the base station operates as a network access node and a peer to peer mode of operation in which devices within a base station coverage area are allowed to communicate directly with one another. Operation proceeds from step  1804  to step  1806 . 
     In step  1806 , the mobile communications device, sends a signal to a base station to signal a wireless terminal desired change in the mode of base station operation. Then, in step  1808 , the mobile communications device monitors for a broadcast signal from the base station indicating a change in base station mode of operation to the indicated mode desired by the mobile communications device. Operation proceeds from step  1808  to step  1810 . In step  1810 , the mobile communications device checks if the monitored for signal has been detected. If the monitored for signal was detected, then operation proceeds from step  1810  to step  1812 ; otherwise, operation proceeds from step  1810  to step  1808  for additional monitoring. In some embodiments, a timeout is associated with the duration of the monitoring, and if the mobile communications device does not receive the monitored for signal within the allocated time, the mobile communications device needs to resend the desired change signal. 
     In step  1812 , the mobile communications device changes the mode of the mobile communications device operation to the mode to which the base station has changed. Operation proceeds from step  1812  to step  1814 . In step  1814 , the mobile communications device signals the base station to switch from the indicated mode of operation to the base station&#39;s previous mode of operation. 
     In some embodiments, the signal of step  1804  indicates a desire for a change from a network access mode of operation to a peer to peer mode of operation. In some embodiments, the signal of step  1804  includes information indicating a level of authority said mobile communications device has to control the base station operation. In some such embodiments, the information indicating the level of authority is one of a device identifier, user identifier, and priority level indicator. 
     In various embodiments, the mobile communications device is a device used by a government agent with authority to override use of the spectrum used by the base station. 
     In some embodiments, the mobile communications device is a cellular network device, and the desired change of step  1806  is a change from a peer to peer mode to a network mode of operation. In some such embodiments, the cellular network device does not support peer to peer operation. 
     In various embodiments, the mobile communications device is a peer to peer device and the desired change is a change from a network access mode to a peer to peer mode of operation. In some such embodiments, the peer to peer device does not support a cellular network mode of operation. In some embodiments, the peer to peer device which does not support a cellular network mode of operation is a device used by a government agent with authority to override the use of the spectrum by the base station. 
       FIG. 25  is a drawing of an exemplary wireless terminal  2900 , e.g., mobile node, in accordance with various embodiments. Exemplary wireless terminal  2900  includes the capability to influence a base station&#39;s mode of operation, e.g., requesting and/or commanding switching between a cellular mode and a peer to peer mode. 
     Exemplary wireless terminal  2900  includes a receiver module  2902 , a transmitter module  2904 , a processor  2906 , user I/O devices  2908 , and memory  2910  coupled together via a bus  2912  over which the various elements may exchange data and information. Memory  2910  includes routines  2914  and data/information  2916 . The processor  2906 , e.g., a CPU, executes the routines  2914  and uses the data/information  2916  in memory  2910  to control the operation of the wireless terminal and implement methods, e.g., a method in accordance with  FIG. 24 . 
     Routines  2914  include communications routine  2918  and wireless terminal control routines  2920 . The wireless terminal control routines  2920  include a base station mode of operation determination module  2922 , a signal generation module  2924 , a broadcast signal detection module  2928  and a communications mode control module  2930 . The signal generation module  2924  includes a base station mode restoration module  2926 . 
     Data/information  2916  includes a determined base station mode of operation  2932 , a generated change signal  2934 , and stored information indicating the level of authority the wireless terminal has to control the base station operations  2936 . Information  2936  includes a wireless terminal device identifier  2938 , a wireless terminal user identifier  2940 , and a priority level indicator  2942 . Data/information  2916  also includes detected broadcast signal information  2944  and current mode of wireless terminal operation information  2946 . 
     The receiver module  2902 , e.g., an OFDM receiver, is coupled to receive antenna  2903 , via which the wireless terminal  2900  receives signals. Received signals include received broadcast signals, e.g., beacon signals, from a base station from which a base station mode of operation can be determined. 
     Transmitter module  2904 , e.g., an OFDM transmitter, is coupled to transmit antenna  2905 , via which the wireless terminal  2900  transmits signals. Transmitted signals include generated change signal  2934  conveying a wireless terminal  2900  desire for a base station to change its mode of operation. Transmitter module  2904  sends the generated change signal  2934  to the base station to communicate the wireless terminal&#39;s desired change in the base station&#39;s mode of operation. The generated change signal  2934  can be, and sometimes is, a request for the base station to change modes. The generated signal  2934  can be, and sometimes is, a command to the base station to change its mode of operation. 
     User I/O devices  2908  include, e.g., keypad, keyboard, switches, mouse, microphone, speaker, display, etc. User I/O devices  2908  are used for operations including inputting user data, accessing output user data, and controlling at least some functions and operations of the wireless terminal, e.g., initiating a communications session. In some embodiments, the user I/O devices  2908  include a special purpose key, switch or button, for use to command a mode switch of the base station. For example, the wireless communications device  2900  is used by a government agent with authority to override use of the spectrum by the base station and includes a special purpose button on the wireless terminal, which when depressed, initiates the generation and transmission of a mode change control signal directed to the base station. 
     Communications routine  2918  implements the various communications protocols used by the wireless terminal  2900 . Base station mode of operation determination module  2922  determines a base station&#39;s mode of operation, the base station mode of operation being one of an access node mode of operation in which the base station operates as a network access node and a peer to peer mode of operation in which devices within a base station coverage area are allowed to communicate directly with one another. Determined base station mode of operation  2932  is an output of determination module  2922 . 
     Signal generation module  2924  generates a signal change signal  2934  indicating a wireless terminal desired change in the base station&#39;s mode of operation. At times, the generated change signal  2934  indicates a desire for a change from a network access mode of operation to a peer to peer mode of operation. At times, the generated change signal  2934  indicates a desire for a change from a peer to peer mode of operation to network access mode of operation. 
     In some embodiments, the change signal conveys a level of authority associated with the change signal. The level of authority, in some embodiments, is based on one or more of wireless terminal identifier, user identifier, and a priority level indicator. In some embodiments, wireless terminal  2900  has a fixed level of authority associated with the device. In some embodiments, wireless terminal  2900  has a variable level of authority, e.g., which changes a function of user identification information and/or priority level access code information. In some such embodiments, the user I/O devices  2908  include a biometric input device for receiving biometric information corresponding to the user, the input biometric information being used to obtain/authenticate authorization information. 
     Base station mode restoration module  2926  generates a restoration signal  2935  to be communicated to a base station, the restoration signal to signal the base station to switch from the indicated mode of operation communicated by the previous change signal to the base station, the indicated mode being the mode in which the base station is currently operating, to the previous mode of base station operation. 
     Broadcast signal detection module  2928  detects a broadcast signal which indicates that the base station has changed the base station mode of operation to an indicated mode of operation desired by the wireless terminal. Detected broadcast signal information  2944  is an output of detection module  2928 . In various embodiments, the detected broadcast signals are beacon signals, e.g., OFDM beacon signal. 
     Communications mode control module  2930  changes the operational mode of the mobile communications device, as indicated by current mode of wireless terminal operation, to match the mode of base station operation to which the base station has transitioned as indicated by a detected broadcast signal. In various embodiments, the wireless terminal  2900  supports communications sessions in both cellular, e.g., access node based mode and peer to peer mode. In some embodiments, the wireless terminal does not support communications sessions in one of the cellular and peer to peer modes of operation. In some such embodiments, the wireless terminal enters a standby state while the spectrum is allocated for the mode in which the wireless terminal can not participate in a communication session, e.g., conserving power. 
     In some embodiments, the wireless terminal  2900  is a device used by a government agent with the authority to override use of the spectrum used by a base station. In some embodiments, the wireless terminal  2900  is a cellular network device, and the wireless terminal indicates a desired change from a peer to peer to a network access mode of operation. In some such embodiment, the cellular network device does not support peer to peer communications. In some embodiments, the wireless terminal  2900  is a peer to peer device, and the wireless terminal indicates a desired change from a network access mode of operation to a peer to peer mode of operation. In some such embodiments, the cellular network device does not support a cellular network mode of operation. In some embodiments, the wireless terminal is a mobile communications device used by a government agent with authority to override use of the spectrum by the base station. 
     In one embodiment, which is a variation based on wireless terminal  2900 , the wireless terminal is a mobile communications device used by a government agent with the authority to override the use of spectrum by the base station, and the device communicates mode change command signals, but does not support either access node based or peer to peer based communications sessions. 
       FIG. 26  is a drawing of a flowchart  1900  of an exemplary method of operating a wireless device, e.g., a mobile node, in accordance with various embodiments. Operation starts in step  1902 , where the wireless device is powered on and initialized. Operation proceeds from start step  1902  to step  1904 , where the wireless device receives a first broadcast signal from a base station. Then, in step  1906 , the wireless device determines from the received first broadcast signal that a frequency band corresponding to the base station is being used for peer to peer communications. Operation proceeds from step  1906  to step  1908 . 
     In step  1908 , the wireless device receives a second broadcast signal from the base station, and then in step  1910 , the wireless device determines from the received second broadcast signal that the second frequency band has been changed to be used as a cellular network band. In response to determining that the frequency band is to be used as a cellular frequency band, operation proceeds from step  1910  to one of alternate steps  1912 ,  1914 , and  1916 . In alternative step  1912 , the wireless device reduces transmission power. In some embodiments, reducing transmission power includes a reduction in transmission power by at least 10 dBs. In some embodiments, reducing transmission power includes ceasing to transmit. In alternative step  1914 , the wireless device terminates an ongoing peer to peer communications session. In alternative step  1916 , the wireless device puts an ongoing peer to peer communications session into a hold state. Operation proceeds from any of steps  1912 ,  1914 ,  1916  to step  1918 . If the wireless terminal does not have an ongoing peer to peer communications session, when making the determination of step  1910 , operation proceeds from step  1910  to step  1918  without traversing alternative steps  1912 ,  1914 , or  1916 . 
     In step  1918 , the wireless device receives a third broadcast signal from the base station, and then in step  1920 , the wireless device determines from the third broadcast signal that said frequency band has been changed to be used for peer to peer communications. Operation proceeds from step  1920  to step  1922 , where the wireless device switches a peer to peer communications session, which was in hold state, if one happens to exist in hold state, to an active state in response to said third broadcast signal. 
     In some embodiments at least some of the received first, second and third broadcast signals include beacon signal bursts. In some embodiments, each of the first, second, and third signals are OFDM beacon signals. 
       FIG. 27  is a drawing of an exemplary wireless terminal, e.g., mobile node, implemented in accordance with various embodiments. Exemplary wireless terminal  3000  supports peer to peer communications sessions. In some embodiments, exemplary wireless terminal  3000  supports peer to peer communications but does not support a cellular mode of operation. Exemplary wireless terminal  3000  includes a receiver module  3002 , a transmission module  3004 , a coupling module  3003 , a processor  3006 , user I/O devices  3008 , a power supply module  3010  and memory  3012  coupled together via a bus  3014  over which the various elements may interchange data and information. Memory  3012  includes routines  3016  and data/information  3018 . The processor  3006 , e.g., a CPU, executes the routines and uses data/information  3018  in memory  3012  to control the operation of the wireless terminal  3000  and implement methods, e.g., a method in accordance with  FIG. 26 . 
     Coupling module  3003 , e.g., a duplex module, couples the receiver module  3002  to antenna  3005  and the transmission module  3004  to antenna  3005 , e.g., coordinating time division duplex operations of wireless terminal  3000 . Power supply module  3012 , which includes a battery  3011 , is used to power up the various components of the wireless terminal  3000 . Power is distributed from the power supply module  3010  to the various components ( 3002 ,  3003 ,  3004 ,  3006 ,  3008 ,  3012 ), via a power bus  3009 . User I/O devices  3008  include, e.g., keypad, keyboard, switches, mouse, microphone, speaker, display, etc. User I/O devices  3008  are used for operation including inputting user data, accessing output user data, and controlling at least some functions and operations of the wireless terminal, e.g., initiating a peer to peer communications session. 
     Routines  3016  include a mode determination module  3020 , a mode control module  3022 , a peer to peer communications session termination module  3024 , a session hold module  3026 , and a peer to peer communications session reestablishment module  3028 . Data/information  3018  includes received broadcast signals  3030 , a determined mode of communications operation  3032 , wireless terminal controlled mode information  3034 , a current level of transmission power information  3035 , power reduction information  3036 , 1st maximum transmission power level information  3038 , 2nd maximum transmission power level information  3040 , and peer to peer communications session information  3042 . The peer to peer communications session information  3042  includes status information  3044 , peer node information  3046 , user data information  3048 , and state information  3050 . 
     Receiver module  3002 , e.g., an OFDM receiver, receives signals including broadcast signals. Receiver module  3002  also receives, at times, user data signals from a peer wireless terminal in a peer to peer communications session with wireless terminal  3000 . Received broadcast signals  3030 , e.g., beacon signals, are used to determine a mode of communication band operation. 
     Transmitter module  3004 , e.g., an OFDM transmitter, transmits user data as part of a peer to peer communications session. In some embodiments, transmission module  3004  also transmits user beacon signals, e.g. OFDM user beacon signals. 
     Mode determination module  3020  determines based on received broadcast signals  3030  a mode of communications band operation, determined mode of communications band operation  3032 . The determined mode of communications band operation indicating a mode of operation in which the frequency band is to be used at a point in time, the determined mode of communication band operation being one of a plurality of frequency band modes including at least a cellular communications mode and a first peer to peer communications mode. 
     Mode control module  3022  controls wireless terminal  3000  device operation as a function of at least one of a mode determination and a change in a determined mode of communications band operation, said mode control module  3022  controlling the transmitter to reduce power in response to determining that the frequency band is to be used as a cellular frequency band. In some embodiments, the controlling the transmitter to reduce power includes reducing transmission power by at least 10 dBs. In some embodiments reducing transmission power includes ceasing to transmit. 
     Thus, in some embodiments, when wireless terminal  3000  is in a peer to peer communications session and the spectrum is reallocated to support access node based operations, the wireless terminal is permitted to continue the peer to peer communications session at a reduced power level. While, in other embodiments, when wireless terminal  3000  is in a peer to peer communications session and the spectrum is reallocated for access node based operation, the wireless terminal terminates or suspends the peer to peer communications session until the spectrum is reallocated for peer to peer usage. In some embodiments, wireless terminal  3000  decides whether to continue with, terminate, or place on hold a peer to peer session interrupted by a spectrum reallocation, in response to other factors, e.g., device identification information, user identity information, priority information, latency requirements, etc. 
     Peer to peer communications session termination module  3024  terminates at least some peer to peer communications sessions in response to a determination that a frequency band is being used as a cellular frequency band. Session hold module  3026  puts an ongoing peer to peer communications session into a hold state in response to a determination that the frequency band is being used as a cellular frequency band. Peer to peer communications session reestablishment module  3028  transitions a peer to peer communications session from a hold state to an active state in response to a determination that the frequency band is to be used for peer to peer communications. 
     Current level of transmission power information  3035  is a monitored level used by mode control module  3022 , when determining a transmission power level reduction in accordance with power reduction information  3036 , e.g., a gain factor of at least 10 dBs, and 1st maximum transmission power level information  3038  and 2nd maximum level transmission power information  3040 . The power level reduction is in response to a detection that spectrum usage is changing from peer to peer to cellular based, and the wireless terminal  3000  continuing with the peer to peer communications session at a reduced power level. In some embodiments, the mode control module  3022  supports 1st and 2nd modes of peer to peer operation from the perspective of the wireless terminal, the second peer to peer mode of operation being a reduced power level mode of operation in which the wireless communications device  3000  uses a lower maximum transmission power level for the transmission of user data than is used in the 1st mode of peer to peer operation. In some embodiments, the 1st mode of wireless terminal peer to peer operation applies when the spectrum is allocated for peer to peer usage, and the second mode of wireless terminal peer to peer operation applies when the spectrum is allocated primarily for cellular access node base operations. 
     Status information  3044  indicates whether the peer to peer communications session is in an active state or a hold state. Status information  3044  also indicates whether the peer to peer communications session is in a first mode of wireless terminal peer to peer operation, e.g., normal power mode, or a second mode of wireless terminal peer to peer operation, reduced power mode. Peer node information  3046  includes peer node identification information, addressing information, and priority level information. User data information  3048 , e.g., voice, image, text, file information, includes user data to be transmitted and received as part of the peer to peer communications session. State information  3050  includes session maintenance information, and stored information used to reestablish a session placed into a hold state. 
       FIG. 28  comprising the combination of  FIG. 28A  and  FIG. 28B  is a drawing of a flowchart  2000  of an exemplary communications method in accordance with various embodiments. Operation of the exemplary communications method starts in step  2002  and proceeds to step  2004 , step  2024  via connecting node A  2006 , and step  2030  via connecting node B  2008 . 
     In step  2004 , a first wireless terminal capable of supporting peer to peer operations and cellular network operations is operated. Step  2004  includes sub-steps  2010 ,  2011 ,  2012 ,  2014 ,  2016 ,  2018 , and  2020 . In sub-step  2010 , the first wireless terminal monitors for paging signals from a base station during a first set of time intervals which are paging time intervals. In various embodiments, during the first set of time intervals the first wireless terminal does not transmit peer to peer signals. In some embodiments, during the first set of time intervals the first wireless terminal also does not receive peer to peer signals. 
     In sub-step  2012 , the first wireless terminal, during a second set of time intervals, which do not overlap said first set of time intervals, is operated to participate in a peer to peer communications session. In some embodiments, the first and second time intervals are interleaved. Sub-step  2012  includes sub-step  2022 , in which the first wireless terminal, during at least a portion of said second set of time intervals is operated to transmit a first wireless terminal identifier used for peer to peer communications. In some such embodiments, the first wireless terminal identifier is communicated via a user beacon signal, e.g., an OFDM user beacon signal including a beacon signal burst including at least one beacon symbol. 
     In some embodiments, the same frequency band is used for paging and for peer to peer communications, and the first wireless terminal need not perform sub-step  2011 . In some embodiments, different frequency bands are used for paging and for peer to peer communications. In some such embodiments, sub-step  2011  is performed in which the first wireless terminal switches the frequency band of a receiver in said wireless terminal when switching between monitoring for pages during a first time interval and operating in a peer to peer mode during a second time interval. 
     Returning to sub-step  2010 , for a detected page signal directed to the first wireless terminal, operation proceeds from sub-step  2010  to sub-step  2014 . In sub-step  2014 , the first wireless terminal decides whether to establish a link with the base station in response to the page directed to the first wireless terminal or to continue with an ongoing peer to peer communication session. In some embodiments, the decision of the step  2014  is a function of at least one of: a priority level associated with the ongoing peer to peer communications session, a priority level associated with the peer wireless terminal in the ongoing peer to peer communications session, a priority level associated with the user of the peer wireless terminal in the ongoing peer to peer communication session, the type of data being communicated in the peer to peer communications session, latency considerations of the data being communicated in the peer to peer session, an estimate of the amount of data remaining to be communicated in the peer to peer communications session, and priority information communicated in the page signal. In some such embodiments, the decision of step  2014  is a function of at least two of: a priority level associated with the ongoing peer to peer communications session, a priority level associated with the peer wireless terminal in the ongoing peer to peer communications session, a priority level associated with the user of the peer wireless terminal in the ongoing peer to peer communication session, the type of data being communicated in the peer to peer communications session, latency considerations of the data being communicated in the peer to peer session, an estimate of the amount of data remaining to be communicated in the peer to peer communications session, and priority information communicated in the page signal. 
     If the decision of sub-step  2014  is to establish a link with the base station which transmitted the page, then operation proceeds to sub-step  2016 , where the first wireless terminal terminates the peer to peer communications session and in sub-step  2018  establishes a link with the base station. However, if the first wireless terminal decides in sub-step  2014  to continue with the ongoing peer to peer communication session, operation proceeds from sub-step  2014  to sub-step  2020  where the first wireless terminal continues with the peer to peer communications session. In some such embodiments, the first wireless terminal, when deciding to perform sub-step  2020 , the first wireless terminal ignores the page, e.g., with no response back to the base station. In other embodiments, the first wireless terminal, when deciding to perform sub-step  2020 , sends a page response signal to the base station indicating the first wireless terminal has received the page but has decided not to establish a link with the base station. 
     Returning to step  2024 , in step  2024 , a second wireless terminal, capable of supporting peer to peer mode operations and cellular network operations, is operated. Step  2024  includes sub-steps  2026  and  2028 . In sub-step  2026 , the second wireless terminal monitors for paging signals from a base station during a third set of time intervals which are paging time intervals. In some such embodiments, the first and third paging time intervals overlap. In sub-step  2028 , the second wireless terminal, during said second set of time intervals, which does not overlap with said first or third set of time intervals participates in a peer to peer communications session. 
     Returning to step  2030 , in step  2030 , a third wireless terminal is operated in a peer to peer communications session during which at least some first time periods occur, wherein the third wireless terminal does not perform paging operations between the start and end of its peer to peer communications session and remains silent during the first time intervals occurring between the start and end of its peer to peer communications session. 
       FIG. 29  is a drawing of an exemplary wireless terminal  3100 , e.g., mobile node, in accordance with various embodiments. Exemplary wireless terminal  3100  monitors for, detects, and processes paging signals in a wireless communications system including dual mode capability including access node based cellular communications and peer to peer communications, and exemplary wireless terminal  3100  supports operation in both modes of operation. 
     Exemplary wireless terminal  3100  includes a receiver module  3102 , a transmitter module  3104 , a processor  3106 , user I/O devices  3108 , and memory  3110  coupled together via a bus  3112  over which the various elements may exchange data and information. User I/O devices  3108  include, e.g., keypad, keyboard, switches, mouse, microphone, speaker, display, etc. User I/O devices  3108  are used for operation including inputting user data, accessing output user data, and controlling at least some functions and operations of the wireless terminal, e.g., initiating a peer to peer communications session or initiating an access node based communications session. 
     Receiver module  3102 , e.g., an OFDM receiver, coupled to receive antenna  3103  via which the wireless terminal receives signals from a base station including paging signals and signals in which the base station is functioning as a point of network attachment for wireless terminal  3100 , e.g., downlink control signals and downlink user data signals. Receiver module  3102  also receives signals from a peer node in a peer to peer communications session with wireless terminal  3100 . 
     Transmitter module  3104 , e.g., an OFDM transmitter, is coupled to transmit antenna  3105 , via which the wireless terminal  3100  transmits signals. Transmitted signals include generated identification signals  3142 , e.g., an OFDM user beacon signal including beacon signal burst, each beacon signal burst including at least one OFDM beacon symbol. Transmitted signals also include access node based session establishment signals, peer to peer session establishment signals, control and user data uplink signals directed to a base station serving as the wireless terminal&#39;s point of network attachment, signals directed to a peer node as part of a peer to peer communications session, and uplink page response signals directed to the base station which transmitted the page directed to wireless terminal  3100 . 
     Memory  3110  includes routines  3114  and data/information  3116 . The processor  3106 , e.g., a CPU, executes the routines  3114  and uses the data/information  3116  in memory  3110  to control the operation of the wireless terminal and implement methods. Routines  3114  include a communications routine  3118  and wireless terminal control routines  3120 . The communications routine  3118  implements the various communications protocols used by the wireless terminal  3100 . The wireless terminal control routines  3120  include a time interval determination module  3122 , a cellular network communications module  3124 , a page signal monitoring module  3126 , a peer to peer communications module  3128 , a wireless terminal identification signal generation module  3130 , a decision module  3132 , and a peer to peer communications session termination module  3134 . The peer to peer communications module  3128  includes a peer to peer communications control module  3129 . 
     Data/information  3116  includes a determined first set of time intervals  3136 , which are paging time intervals, a determined second set of time intervals  3138 , a detected page signal  3140 , a generated wireless terminal identification signal, e.g., a generated user beacon associated with wireless terminal  3100 , paging band information  3144 , peer to peer band information  3146  and receiver band setting information  3148 . 
     Time interval determination module  3122  determines first and second sets of time intervals ( 3136 ,  3138 ), respectively), the first and second sets of time intervals being non-overlapping sets, the first set of time intervals being paging time intervals. Cellular network communications module  3124  supports cellular network communications operations, e.g., operations in which the wireless terminal uses the base station as a network attachment point to communicate with another wireless terminal via the cellular communications network. Page signal monitoring module  3126  monitors for paging signals from a base station during the first set of time intervals  3136 . Information  3140  represents a detected page signal directed to wireless terminal  3100 . 
     Peer to peer communications module  3128  supports peer to peer communications signaling operations during the second set of time intervals  3138  but not during the first set of time intervals  3136 . Peer to peer transmission control module  3129  restrains the wireless terminal from transmitting peer to peer signals during the first time intervals. In some embodiments, the wireless terminal is also controlled to suspend detection operations of peer to peer signals during the first time intervals. In various embodiments, members of the first set of time intervals are interleaved with members of the second set of time intervals. 
     Wireless terminal identification signal generation module  3130  generates a wireless terminal identifier  3142  used for peer to peer communications, e.g., an OFDM beacon signal burst or sequence of bursts, each beacon signal burst including at least one beacon symbol. Decision module  3132  decides between establishing a communication link with a base station in response to a page which was received or continuing with an on-going peer to peer communications session. Peer to peer communications session termination module  3134  terminates a peer to peer communications session in response to a received page directed to the wireless terminal  3100 . 
     Paging band information  3144  includes information identifying the frequency band used for paging, while peer to peer band information  3146  identifies the frequency band used for peer to peer communications. In some embodiments the same frequency band is used for paging and peer to peer communications. In some embodiments, different frequency bands are used for paging and peer to peer communications. In some such embodiments, receiver module  3102  includes a tunable receiver responsive to a mode control signal for switching between the different frequency bands used for paging and peer to peer communications. Receiver band setting information  3148  includes information indicating the current setting of the receiver module  3102  and control signaling used to change the setting of the receiver module  3102 . 
       FIG. 30  is a drawing of an exemplary communications system  2100  in accordance with various embodiments. Exemplary communications system  2100  includes a plurality of base stations (base station 1  2102 , base station 2  2104 , base station 3  2106 ) and a plurality of non-access beacon signal transmitter nodes (non-access beacon signal transmitter node 1  2108 , non-access beacon signal transmitter node 2  2112 , non-access beacon signal transmitter node 3  2110 ). The base stations ( 2102 ,  2104 ,  2106 ) are coupled to network nodes ( 2114 ,  2118 ,  2118 ) via network links ( 2120 ,  2128 ,  2126 ), respectively. In addition, system  2100  includes network node 2116 which is coupled to (network node 2114, network node 2118, non-access beacon signal transmitter  2108 , and other network nodes and/or the Internet) via network links ( 2122 ,  2124 ,  2130 ,  2131 ), respectively. Network links ( 2120 ,  2122 ,  2124 ,  2126 ,  2128 ,  2130 ,  2131 ) are, e.g., fiber optic links and/or wired links. 
     Some of the base stations (BS 1  2102 , BS 2  2104 ) support both peer to peer communications in the base station region and also operate as access nodes. Base station 3  2106  functions as an access node and does not support peer to peer communications in its coverage region. Each base station (BS 1  102 , BS 2  2104 , BS 3  2106 ) has a corresponding region ( 2103 ,  2105 ,  2107 ) which represents a cellular coverage area when in the network access mode. Regions ( 2103 ,  2105 ) also represent base station beacon transmission regions when supporting peer to peer communications. 
     The base stations ( 2102 ,  2104 ,  2106 ) and the non-access beacon signal transmitter nodes ( 2108 ,  2110 ,  2112 ) transmit beacon signals including beacon signal bursts, e.g., OFDM beacon signal bursts each beacon signal burst including at least one beacon symbol. 
     Exemplary system  2100  also includes a plurality of wireless terminals, e.g., mobile nodes, (MN 1  2150 , MN 2  2152 , MN 3  2154 , MN 4  2156 , MN 5  2158 , MN 6  2160 , MN 7  2162 , MN 8  2164 ), which may move throughout the system. MN 1  2150  is using BS 1  2102  as an access node and is coupled to BS 1  2102  via link  2166 . MN 2  2152  is using BS 1  2102  as an access node and is coupled to BS 1  2102  via link  2168 . MN 1  2150  and MN 2  2152  are using access node beacon signals transmitted from BS 1  2102  for synchronization. MN 3  2154  is in a peer to peer communications session with MN 4  2156  using peer to peer link  2170 . MN 3  2154  and MN 4  2156  are using peer to peer beacon signals from BS 1  2102  for synchronization purposes. 
     MN 5  2158  is using BS 3  2106  as an access node and is coupled to BS 3  2106  via link  2172 . MN 6  2160  is using BS 3  2106  as an access node and is coupled to BS 3  2106  via link  2174 . MN 5  2158  and MN 6  2160  are using access node beacon signals transmitted from BS 3  2174  for synchronization. 
     MN 7  2162  is in a peer to peer communications session with MN 8  2164  using peer to peer link  2176 . MN 7  2162  and MN 8  2164  are using peer to peer beacon signals from non-access beacon signal transmitter node 3  2110  for synchronization purposes. 
     Base station 1  2102  includes a peer to peer beacon signal generation module  2132 , an access node beacon signal generation module  2134 , a transmitter module  2136 , a receiver module  2138  and a switching module  2140 . Peer to peer beacon signal generation module  2132  generates beacon signals used to support peer to peer communications, while access node beacon signal generation module  2134  generates beacon signals used to support cellular network communications. Transmitter module  2136 , e.g., an OFDM transmitter, transmits generated peer to peer beacon signals and generated access node beacon signals. Transmitter module  2136  also transmits control and user data signals to wireless terminals when functioning as an access node. Receiver module  2138 , e.g., an OFDM receiver, receives signals such as access request signals, control signals and user data from wireless terminals, e.g., mobile nodes using the base station as a point of network attachment. Switching module  2140  supports switching between peer to peer and cellular modes of operation using the same frequency band for peer to peer and cellular modes of operation at different times. Base station 1  2102  transmits different beacon signals during peer to peer and cellular modes of operation. 
     Non-access beacon signal transmitter node 2  2112  and non-access beacon signal transmitter node 3  2110  are standalone devices. Non-access beacon signal transmitter node 2  2112  includes a transmitter  2142 , a battery  2144  and a receiver  2146 . Battery  2144  powers non-access beacon signal transmitter node 2  2112 . Transmitter  2142  transmits beacon signals which are utilized by mobile nodes in its transmitter coverage region  2113  for synchronization purposes in supporting peer to peer communications sessions. The beacon signal transmitter  2142  does not relay any user data. Receiver  2146  receives a broadcast signal used for timing synchronization purposes. The receiver  2146  for receiving a broadcast signal used for timing synchronization purposes is one of a GSM receiver, a satellite receiver, and a cellular network receiver. Satellite receivers include, e.g., a GPS receiver, broadcast TV and/or radio signal satellite receiver, proprietary satellite receiver or government controlled satellite receiver. Cellular network receivers include, e.g., CDMA, OFDM, GSM, etc., receivers. In some embodiments, a non-access beacon signal transmitter node includes a plurality of different types of receivers for receiving different types of broadcast signals, e.g., with different signals being available in some areas but not in others. 
     In various embodiments, at least some of the base stations, which transmit beacon signals are not synchronized with respect to one another. In various embodiments, at least some of the non-access beacon signal transmitter nodes, which transmit beacon signals, are not synchronized with respect to one another. For example, non-access beacon signal transmitter node 3  2110 , in some embodiments, does not include a receiver, and its transmitted beacon signals into its transmitter region  2111  are free running with respect to the other non-access beacon signal transmitters in system  2100  and the base stations in system  2100 . 
     Non-access beacon signal transmitter module 3  2110  includes a solar cell  2148 , and the solar cell  2148  is a solar power source conversion device for powering non-access beacon signal transmitter node 3  2110  during at least some of the time. 
     Non-beacon access beacon signal transmitter node 1  2108  is coupled to the network via link  2130  thus facilitating timing synchronization information to be communicated to the node  2108 , allowing for its beacon signal transmission into its transmitter region  2109  to be synchronized with respect to an overall system timing reference. No user data is communicated over link  2130 . 
       FIG. 31  is a drawing of an exemplary wireless communications system  2200  which supports both peer to peer communications and cellular communications in accordance with various embodiments. Exemplary communications system  2200  includes a plurality of wireless terminals, e.g., mobile nodes, and a plurality of base stations. At least some of the plurality of base stations are both network access node and peer to peer capable such as exemplary base station  2212 . Exemplary communications system  2220  also includes some base stations which function as access nodes but do not support peer to peer communications such as exemplary base station  2280  and some non-access beacon signal transmitter nodes for supporting peer to peer communications such as exemplary non-access beacon signal transmitter node  2282 . 
     System  2200  includes wireless terminal 1A  2202  and wireless terminal 1B  2204 , which both support peer to peer and cellular communications; wireless terminal 2A  2206  and wireless terminal 2B  2210 , which both support peer to peer communications but not cellular network communications; and wireless terminal 3  2208  which supports cellular network communications but not peer to peer communications. 
     Wireless terminal 1A  2202  includes a beacon signal processing module  2216 , a peer to peer communications module  2218 , a cellular network communications module  2230 , a mode control module  2232 , current mode information  2234  and subscriber plan identification information  2236 . Beacon signal processing module  2216  processes beacon signals received from base stations and/or non-access beacon signal transmitter nodes. The beacon signals are uses for supporting cellular and peer to peer communications, e.g., providing synchronization, identification, mode and/or priority information. Peer to peer communications module  2218  performs operations supporting peer to peer communications. Cellular network communications module  2230  performs operations supporting cellular communications in which the wireless terminal 1A  2202  is communicating via a wireless communications link with a base station functioning as an access node and providing a point of network attachment. Mode control module  2232  switches between peer to peer and cellular modes of operation, as wireless terminal 1A  2202  supports at most one of peer to peer mode and cellular mode operation at a given time. Current mode information  2234  indicates which of the peer to peer mode and cellular mode wireless terminal 1A  2202  is currently operating in. 
     Wireless terminal 1B  2204  includes a beacon signal processing module  2238 , a peer to peer communications module  2240 , a cellular network communications module  2242 , a communications control module  2244 , and subscriber plan identification information  2246 . Beacon signal processing module  2238  processes beacon signals received from base stations and/or non-access beacon signal transmitter nodes. Peer to peer communications module  2240  performs operations supporting peer to peer communications. Cellular network communications module  2242  performs operations supporting cellular communications in which the wireless terminal 1B  2204  is communicating via a wireless communications link with a base station functioning as an access node and providing a point of network attachment. Communications control module  2244  switches between peer to peer and cellular modes of operation, as wireless terminal 1A  2202  controls the wireless terminal to maintain peer to peer and cellular network communications sessions at the same time. 
     Wireless terminal 2A  2206  includes a beacon signal processing module  2248 , a peer to peer communications module  2250 , and subscriber plan identification information  2252 . Beacon signal processing module  2248  processes beacon signals received from base stations and/or non-access beacon signal transmitter nodes. Peer to peer communications module  2250  performs operations supporting peer to peer communications. Wireless terminal 2B  2210  includes a beacon signal processing module  2260 , a peer to peer communications module  2262 , and subscriber plan identification information  2264 . Beacon signal processing module  2260  processes beacon signals received from base stations and/or non-access beacon signal transmitter nodes. Peer to peer communications module  2262  performs operations supporting peer to peer communications. 
     Wireless terminal 3  2208  includes a beacon signal processing module  2254 , a cellular network communications module  2256 , and subscriber plan identification information  2258 . Beacon signal processing module  2254  processes beacon signals received from base stations and/or non-access beacon signal transmitter nodes. Cellular network communications module  2256  performs operations supporting cellular network communications. 
     Base station  2212  includes a beacon transmission module  2213 . Beacon signal transmission module  2213  transmits beacon signals used for communications synchronization, identification, mode, and/or priority information. In some embodiments, at least some of the beacon signals are OFDM beacon signals including beacons signal bursts, each beacon signal burst including at least one beacon symbol. Base station  2212  is coupled to other network nodes, e.g., other base station, routers, AAA nodes, home agent nodes, etc, and/or the Internet via link  2214 . Base station  2280  is coupled to other network nodes and/or the Internet via network link  2281 . Network links  2214 ,  2281  are, e.g., fiber optic links and/or wired links. 
     Dotted line  2268  between wireless terminal 1A  2202  and base station  2212  indicates that WT 1A  2202  can operate in a cellular communication mode and have a wireless communication link with a base station. Dotted line  2266  between wireless terminal 1A  2202  and WT 2A  2206   2212  indicates that WT 1A  2202  and WT 2A  2206  can operate in a peer to peer communications mode and have a wireless communication link with another wireless terminal. The lines  2266  and  2268  have been indicated as dotted lines to indicate that WT 1A  2202  switches between the two modes. 
     Solid line  2274  between wireless terminal 1B  2204  and base station  2212  indicates that WT 1B  2204  can operate in a cellular communication mode and have a wireless communication link with a base station. Solid line  2272  between wireless terminal 1B  2204  and WT 2B  2206   2210  indicates that WT 1B  2204  and WT 2B  2210  can operate in a peer to peer communications mode and have a wireless communication link with another wireless terminal. The lines  2272  and  2274  have been indicated as solid lines to indicate that WT 1B can maintain peer to peer and cellular network communications sessions at the same time. 
     Line  2270  between wireless terminal 3  2208  and base station  2212  indicates that WT 3  2208  can operate in a cellular communication mode and have a wireless communication link with a base station. 
     The various wireless terminals ( 2202 ,  2204 ,  2206 ,  2208 ,  2210 ) include subscriber plan identification information ( 2236 ,  2246 ,  2252 ,  2258 ,  2264 ), respectively. In some embodiments, a set of wireless terminals correspond to a communications service subscriber who subscribes to a family plan which supports multiple communications devices some of which have different capabilities. For example, in one embodiment, the set of wireless terminals corresponding to the communications service subscriber who subscribes to a family plan includes WT 1A  2202 , WT 1B  2204 , WT 2A  2206 , and WT 3  2208 . 
     In some embodiments, the peer to peer communications modules ( 2218 ,  2240 ,  2250 ,  2262 ) are OFDM communications modules. In some embodiments the cellular network communications modules ( 2230 ,  2242 ,  2256 ) are OFDM communications modules. In some embodiments, the peer to peer communications modules ( 2218 ,  2240 ,  2250 ,  2262 ) are OFDM communications modules, and the cellular network communications modules ( 2230 ,  2242 ,  2256 ) are CDMA communications modules. In some embodiments, the peer to peer communications modules ( 2218 ,  2240 ,  2250 ,  2262 ) are OFDM communications modules, and the cellular network communications modules ( 2230 ,  2242 ,  2256 ) are GSM communications modules. 
       FIG. 32  is a drawing  3200  illustrating exemplary beacon burst time position hopping in accordance with various embodiments. Horizontal axis  3202  represents time while vertical axis  3204  represents frequency, e.g., OFDM tones in a frequency band, e.g., a non-infrastructure frequency band being used for peer to peer communications. A wireless terminal receives an external broadcast signal  3206  which the wireless terminal uses a timing reference signal and upon which it bases its timing structure. The external reference signal repeats as indicated by signal  3206 ′. In some embodiments, the timing reference point is derived from information conveyed by the received broadcast signal. In this example, the peer to peer timing structure being used by the wireless terminal includes a sequence of slots used for beacon signaling, each time slot is associated with a beacon signaling resource (slot 1 beacon signaling resource  3208 , slot 2 beacon signaling resource  3210 , slot 3 beacon signaling resource  3212 . The slots repeat as indicated by slot 1 beacon signaling resource  3208 ′. Each slot beacon signaling resource represents a block of air link resources, e.g., OFDM tone-symbols. 
     The start of each beacon signaling resources slot ( 3208 ,  3210 ,  3212 ) is referenced with respect a predetermined timing offset (T1  3214 , T2  3216 , T3  3218 ). In some embodiments, the time duration of each beacon signaling slot is the same. In some embodiments T2−T1=T3−T2. 
     Within each beacon signaling slot resource ( 3208 ,  3210 ,  3212 ), the wireless terminal transmits a beacon signal burst ( 3220 ,  3222 ,  3224 ) including at least one beacon symbol ( 3226 ,  3228 ,  3230 ), the beacon symbol being a relatively high power symbol with respect to data symbols transmitted by the wireless terminal. In this example, the time position of the beacon signal burst with the beacon resource slot is hopped from one slot to the next in accordance with a hopping function used by the wireless terminal. The hopping function varies the time of the beacon signal burst from the start of the slot as indicated by different time offset values (T4  3234 , T5  3236 , T6  3238 ) corresponding to (slot 1, slot 2, slot 3), respectively. The hopping function determines the time offset as a function of a wireless terminal identifier, a user identifier, and/or a priority level value. In some embodiments, other inputs can be used by the hopping function, e.g., a received broadcast value associated with the spectrum, a received key, a value associated with a designated area, a value associated with a sector, etc. 
     In this example, the same tone is used by the wireless terminal for the beacon symbol ( 3226 ,  3228 ,  3230 ,  3226 ′) of the beacon signal bursts ( 3220 ,  3220 ,  3224 ,  3220 ′), respectively, in slots resources ( 3208 ,  3210 ,  3212 ,  3208 ′), respectively. Different wireless may, and sometimes do use a different tone for the beacon symbol. 
       FIG. 33  is a drawing  3300  illustrating exemplary beacon burst time position hopping and beacon symbol tone hopping in accordance with various embodiments. Horizontal axis  3302  represents time while vertical axis  3304  represents frequency, e.g., OFDM tones in a frequency band, e.g., a non-infrastructure frequency band being used for peer to peer communications. A wireless terminal receives an external broadcast signal  3306  which the wireless terminal uses a timing reference signal and upon which it bases its timing structure. The external reference signal repeats as indicated by signal  3306 ′. In some embodiments, the timing reference point is derived from information conveyed by the received broadcast signal. In this example, the peer to peer timing structure being used by the wireless terminal includes a sequence of slots used for beacon signaling, each time slot is associated with a beacon signaling resource (slot 1 beacon signaling resource  3308 , slot 2 beacon signaling resource  3310 , slot 3 beacon signaling resource  3312 ). The slots repeat as indicated by slot 1 beacon signaling resource  3308 ′. Each slot beacon signaling resource represents a block of air link resources, e.g., OFDM tone-symbols. 
     The start of each beacon signaling resources slot ( 3308 ,  3310 ,  3312 ) is referenced with respect a predetermined timing offset (T1  3314 , T2  3316 , T3  3318 ) from the external timing reference signal  3306 . In some embodiments, the time duration of each beacon signaling slot is the same. In some embodiments T2−T1=T3−T2. 
     Within each beacon signaling slot resource ( 3308 ,  3310 ,  3312 ), the wireless terminal transmits a beacon signal burst ( 3320 ,  3322 ,  3324 ) including at least one beacon symbol ( 3326 ,  3328 ,  3330 ), the beacon symbol being a relatively high power symbol with respect to data symbols transmitted by the wireless terminal. In this example, the time position of the beacon signal burst with the beacon resource slot is hopped from one slot to the next in accordance with a time hopping function used by the wireless terminal. The hopping function varies the time of the beacon signal burst from the start of the slot as indicated by different time offset values (T4  3334 , T5  3336 , T6  3338 ) corresponding to (slot 1, slot 2, slot 3), respectively. The hopping function determines the time offset as a function of a wireless terminal identifier, a user identifier, and/or a priority level value. In some embodiments, other inputs can be used by the hopping function, e.g., a received broadcast value associated with the spectrum, a received key, a value associated with a designated area, a value associated with a sector, etc. 
     In this example, the tone of the beacon signal used by the wireless terminal for the beacon symbol ( 3326 ,  3328 ,  3330 ) of the beacon signal bursts ( 3320 ,  3322 ,  3324 ), respectively, in slots resources ( 3308 ,  3310 ,  3312 ), respectively, is also hopped from one slot to another in accordance with a tone hopping function. Inputs to the tone hopping function include one or more of a wireless terminal identifier, a user identifier, a priority level value, a received broadcast value associated with the spectrum, a received key, a value associated with a designated area, and a value associated with a sector. 
     In this example, the next iteration of beacon signaling resource slot 1  3308 ′ has the beacon symbol  3326 ′ of beacon burst  3320 ′ placed in the same OFDM tone-symbol position of the resource  3308 ′ as the beacon symbol  3326  of beacon burst  3320  in resource  3308 . In some embodiments, two separate hopping functions are used, one for beacon burst time hopping and the other for tone hopping. In some embodiments, the beacon burst time position hopping function and the tone hopping function have the same sequence length. In some embodiments, the beacon burst time position hopping function and the tone hopping function have different sequence lengths. For example, the two sequence lengths may be co-prime with each other. Alternatively, the ratio of one sequence length to the other sequence length may be an integer. In other embodiments, one hopping function is used for both beacon burst time hopping and tone hopping. Specifically, suppose that each beacon signaling resource slot  3308 ,  3310 ,  3312  includes M symbol times and every symbol time includes N tones. Then, in each slot, the hopping function outputs a number, which uniquely identifies one specific tone at one specific symbol time. For example, the number can be 0, 1, . . . , M*N−1, where M and N are positive integers. In some embodiments, N is at least 100 and M is at least 20, although in other embodiments, the values may be smaller. 
       FIG. 34  is a drawing  3400  illustrating exemplary coordinated timing in a peer to peer communications band in accordance with various embodiments. Drawing  3400  includes exemplary 1st and 2nd wireless terminal ( 3402 ,  3404 ), e.g., peer mobile nodes. Upper drawing portion  3401  is used to illustrate operations of wireless terminal 1  3402 , while lower drawing portion  3403  is used to illustrate operations of wireless terminal 2  3404 . Horizontal axes  3406  represents time, while vertical axes  3408  represents frequency, e.g., OFDM tones in the peer to peer frequency band. 
     Both wireless terminals ( 3402 ,  3404 ) receive and use external broadcast signal  3410  to obtain timing reference. Based on the timing reference signal  3410 , both wireless terminals ( 3402 ,  3404 ) recognize beacon signaling resource slots  3412  and  3414 . Wireless terminal 1  3402  transmits a beacon signal burst  3416  including beacon symbol  3418  during time interval  3440 , and beacon signal burst  3420  including beacon symbol  3422  during time interval  3442 . Wireless terminal 2  3404  is monitoring for beacon symbols from other wireless terminals during time intervals  3444 ,  3446 ,  3448 , and  3450 . Since time interval  3440  is with time interval  3446  wireless terminal 2 is able to detect the beacon symbol  3418  from wireless terminal 1  3402 . Since time interval  3442  is within time interval  3450  wireless terminal 2 is able to detect the beacon symbol  3422  from wireless terminal 1  3402 . 
     Wireless terminal 2  3404  transmits a beacon signal burst  3424  including beacon symbol  3426  during time interval  3452 , and beacon signal burst  3428  including beacon symbol  3430  during time interval  3454 . Wireless terminal 1  3402  is monitoring for beacon symbols from other wireless terminals during time intervals  3432 ,  3434 ,  3436 , and  3438 . Since time interval  3452  is within time interval  3432  wireless terminal 1 is able to detect the beacon symbol  3426  from wireless terminal 2  3404 . Since time interval  3454  is within time interval  3436  wireless terminal 1 is able to detect the beacon symbol  3430  from wireless terminal 2  3404 . 
     In this example, both wireless terminals are able to detect beacon signals from each other. The coordinated timing structure based on a reference allows efficient operation and reduced power consumption, since modules within a wireless terminal can be powered down when transmission and/or monitoring is not required, e.g., during silence modes of operation. 
     Time hopping of the beacon burst, e.g., as a function of a wireless terminal identifier, facilitates resolution of a problem where both wireless terminal 1 and wireless terminal 2 should happen to transmit a beacon signal burst during one beacon signaling resource slot. In some embodiments, the beacon burst time hopping is structured so that at least some beacon signal bursts transmitted by two peer wireless terminals will be non-overlapping. In some embodiments, a wireless terminal, occasionally, refrains from transmitting its beacon burst during a beacon signaling resource and monitors for the full duration of the beacon signaling resource. 
     Additional embodiments, features and variations will now be discussed. 
     An infrastructure network usually includes a base station, which provides service to terminals in a given geographical area. In an exemplary embodiment, a base station of an infrastructure network uses a first (infrastructure) spectrum band to provide service in a geographical area. Meanwhile, a second (non-infrastructure) spectrum band, which is different from the infrastructure spectrum band, is also available for the terminals in the area, e.g., to be used for an ad hoc network. 
     In accordance with various embodiments, in order to facilitate the timing and/or frequency synchronization in the ad hoc network using the non-infrastructure spectrum band, the infrastructure base station transmits a beacon signal. 
     In an exemplary embodiment, the base station transmits the beacon signal in the infrastructure spectrum band. The desired common timing and/or frequency reference to be used in the non-infrastructure spectrum band can be determined from the beacon signal. In addition, the base station may, and sometimes does, send system information about the frequency location of the non-infrastructure spectrum band and the type of service provided in the non-infrastructure spectrum band, e.g., TDD (time division duplex) or ad hoc networking. The system information is sent using the beacon signal and/or other broadcast control signals. 
     A wireless terminal first tunes to the infrastructure spectrum band to detect the beacon signal and derives the timing and/or frequency reference to be used in the non-infrastructure spectrum band. The wireless terminal further receives the system information from the beacon and/or other broadcast control signals, and determines the frequency location of the non-infrastructure spectrum band, e.g., carrier frequency. The wireless terminal tunes to the non-infrastructure spectrum band and uses the acquired timing and/or frequency synchronization to start a communication link in the non-infrastructure spectrum band. 
     In another embodiment, the base station transmits the beacon signal in the non-infrastructure spectrum band, so that if the wireless terminal directly tunes to the non-infrastructure spectrum band, the wireless terminal can derive the desired common timing and/or frequency reference from the beacon signal. In that embodiment, the base station may, and sometimes does, additionally transmit beacon and/or other broadcast control signals in the infrastructure spectrum band as well as send system information about the frequency location of the non-infrastructure spectrum band and the type of service provided in the non-infrastructure spectrum band. 
     In yet another embodiment, in which the infrastructure spectrum band may not exist, a special transmitter is set in a geographic area to transmit a system beacon signal in each of the non-infrastructure spectrum bands that are available for use in the vicinity of the geographical area in which the special transmitter sits. In one embodiment, at a given time, the special transmitter transmits at most one beacon signal burst in a spectrum band. The special transmitter hops across each of the available spectrum bands and transmits the beacon signal burst successively from one spectrum band to another. A wireless terminal is to scan a candidate spectrum band to see whether a system beacon signal can be detected in the candidate spectrum band. If a system beacon signal is detected, then the candidate spectrum band is available for use. Otherwise, the wireless terminal, in some embodiments, is not allowed to use the candidate spectrum band, in which case the wireless terminal may have to scan another candidate spectrum band to find an available spectrum band to use. 
     After the wireless terminal obtains the timing and/or frequency reference from the beacon signal, the wireless terminal then tunes to the non-infrastructure spectrum band. The wireless terminal, in some embodiments, starts to transmit its own user beacon signal in the non-infrastructure spectrum band. Similar to the beacon signal sent by the infrastructure base station, the user beacon signal also includes a sequence of beacon signal bursts in a spectrum band. However, the user beacon signal, in some embodiments, is different from the beacon signal sent by the infrastructure base station in at least one of the following ways: the periodicity of the beacon signal bursts, the tone used in a beacon signal burst, and the hopping pattern of the tones used in successive beacon signal bursts. The wireless terminal may, and sometimes does, further listen to the non-infrastructure spectrum band to detect the presence of a user beacon signal sent by another wireless terminal. In some embodiments, the wireless terminal determines transmission and/or detection of user beacon signals as a function of the timing and/or frequency reference from the beacon signal sent by the infrastructure base station. When wireless terminals derive their timing and/or frequency reference from the same source, e.g., the same infrastructure base station beacon signal, it is easy for them to detect each other&#39;s presence and to establish communication links. 
     In accordance with a feature of some exemplary embodiments, while a wireless terminal is in a peer-to-peer communication session in the non-infrastructure spectrum band, the wireless terminal may, and sometimes does, periodically suspend the session for a short time period and tune to the infrastructure spectrum band, e.g., to check whether there is a page for the terminal. The time periods in which the wireless terminal checks pages are, in some embodiments, pre-determined, so that both the wireless terminal and the base station can be synchronized on when a page should be delivered. In some embodiments, a set of wireless terminals in the peer-to-peer communication sessions have a common time period in which each of those wireless terminals suspend the sessions in the non-infrastructure spectrum band and check pages in the infrastructure spectrum band. Advantageously, this synchronization helps reduce the wastage of session time in the peer-to-peer sessions. 
     In accordance with various embodiments, the infrastructure base station also provides service in the non-infrastructure spectrum band, e.g., to provide peer-to-peer communication service and/or to provide TDD service. The base station in some embodiments transmits the beacon signal in such a way that after the wireless terminal receives the beacon signal the wireless terminal can predict the signal quality of a data session if the wireless terminal is to establish a communication link with the base station. In one embodiment, the transmission power of the beacon signal is the same for each of such base stations. In another embodiment, the data session, e.g., at a given coding and modulation rate, is sent at a transmission power, which is a function of the transmission power of the beacon signal. For example, the per minimum transmission unit transmission power of the data session is a fixed dB amount, e.g., 10 dBs or 16 dBs, below the transmission power of the beacon symbols of the beacon signal. 
     While described primarily in the context of an OFDM system, the methods and apparatus of various embodiments are applicable to a wide range of communications systems including many non-OFDM, and/or many non-cellular systems. 
     In various embodiments nodes described herein are implemented using one or more modules to perform the steps corresponding to one or more methods, for example, generating a beacon signal, transmitting a beacon signal, receiving beacon signals, monitoring for beacon signals, recovering information from received beacon signals, determining a timing adjustment, implementing a timing adjustment, changing a mode of operation, initiating a communication session, etc. In some embodiments various features are implemented using modules. Such modules may be implemented using software, hardware or a combination of software and hardware. Many of the above described methods or method steps can be implemented using machine executable instructions, such as software, included in a machine readable medium such as a memory device, e.g., RAM, floppy disk, etc. to control a machine, e.g., general purpose computer with or without additional hardware, to implement all or portions of the above described methods, e.g., in one or more nodes. Accordingly, among other things, various embodiments are directed to a machine-readable medium including machine executable instructions for causing a machine, e.g., processor and associated hardware, to perform one or more of the steps of the above-described method(s). 
     Numerous additional variations on the methods and apparatus described above will be apparent to those skilled in the art in view of the above descriptions. Such variations are to be considered within scope. The methods and apparatus of various embodiments may be, and in various embodiments are, used with CDMA, orthogonal frequency division multiplexing (OFDM), and/or various other types of communications techniques which may be used to provide wireless communications links between access nodes and mobile nodes. In some embodiments the access nodes are implemented as base stations which establish communications links with mobile nodes using OFDM and/or CDMA. In various embodiments the mobile nodes are implemented as notebook computers, personal data assistants (PDAs), or other portable devices including receiver/transmitter circuits and logic and/or routines, for implementing the methods of various embodiments.