Patent Publication Number: US-8112108-B2

Title: Methods and apparatus facilitating and/or making wireless resource reuse decisions

Description:
FIELD 
     Various embodiments relate to wireless communications, and more particularly, to methods and apparatus related to reuse of a wireless resource. 
     BACKGROUND 
     In a wireless communications systems there are typically a limited amount of designated air link resources which may be used by members of the system. It would be beneficial, for purposes of efficiency and/or throughput, if at least some of the designated air link resources could be used concurrently by two different connections, e.g., two different connections which would have low interference with respect to one another if they were both to use the same resource concurrently. In a wireless communications system lacking centralized control it may be problematic to determine whether a particular resource which is in use by a first connection may be reused by another connection. Before two different connections to the same resource, one would like to make sure that both connections would be expected to achieve an acceptable communication reception quality level. 
     Based on the above discussion there is a need for new methods and apparatus facilitating reuse of a wireless resource, particularly in a wireless communications system lacking centralized control. 
     SUMMARY 
     Methods and apparatus related to reuse of a wireless resource are described. Various methods and apparatus are well suited to wireless communications systems lacking centralized control, e.g., an ad hoc peer to peer wireless communications system. 
     In some embodiments, a first wireless device of a first connection generates and transmits one or more control signals to be used by wireless devices of a second connection to make a resource reuse decision. The first connection may be, and sometimes is, an existing active connection. The second connection may be, and sometimes is, a potential connection. However, the approach is not limited to first and second connections being existing and potential connections. For a control signal, the first wireless device sets a transmission power level of the control signal based upon a predetermined relationship to at least one other signal previously communicated on the first connection, e.g., a received peer discovery or a received paging signal. In some embodiments, the one or more control signals are single tone OFDM signals. A transmitted control signal from the first device, transmitted at power level in accordance with predetermined relationship, facilitates the estimation of one or more expected SINRs by one or more devices of the second connection. 
     An exemplary communications method implemented in a first node, in accordance with some embodiments, comprises: receiving a first signal from a second node; determining a first power level of the received first signal; and transmitting a second signal at a second power level which has a predetermined relationship to the determined first power level. In some embodiments, the predetermined relationship is that the second power level is inversely proportional to the determined first power level. An exemplary first node, in accordance with some embodiments, comprises: at least one processor configured to: receive a first signal from a second node; determine a first power level of the received first signal; and transmit a second signal at a second power level which has a predetermined relationship to the determined first power level. The exemplary first node further comprises memory coupled to said at least one processor. 
     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 of various embodiments are discussed in the detailed description which follows. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a drawing of an exemplary wireless communications system in accordance with an exemplary embodiment. 
         FIG. 2  is a drawing illustrating four exemplary wireless communications devices and is used to describe features of some embodiments. 
         FIG. 3  is a drawing illustrating four exemplary wireless communications devices and is used to describe features of some embodiments. 
         FIG. 4A  is a first part of a three part flowchart of an exemplary communications method in accordance with an exemplary embodiment. 
         FIG. 4B  is a second part of a three part flowchart of an exemplary communications method in accordance with an exemplary embodiment. 
         FIG. 4C  is a third part of a three part flowchart of an exemplary communications method in accordance with an exemplary embodiment. 
         FIG. 5A  is a first part of two part flowchart of an exemplary method of operating a communications device in accordance with an exemplary embodiment. 
         FIG. 5B  is a second part of a two part flowchart of an exemplary method of operating a communications device in accordance with an exemplary embodiment. 
         FIG. 6  is a drawing of an exemplary communications device in accordance with an exemplary embodiment. 
         FIG. 7  is an assembly of modules which can, and in some embodiments are, used in the communications device illustrated in  FIG. 6 . 
         FIG. 8A  is a first part of a flowchart of another exemplary method of operating a communications device in accordance with an exemplary embodiment. 
         FIG. 8B  is a second part of the flowchart of said another exemplary method of operating a communications device in accordance with an exemplary embodiment. 
         FIG. 9  is a drawing of an exemplary communications device in accordance with an exemplary embodiment. 
         FIG. 10  is an assembly of modules which can, and in some embodiments are, used in the communications device illustrated in  FIG. 9 . 
         FIG. 11  includes drawing which illustrates an example of a uni-directional resource case. 
         FIG. 12  includes drawing which illustrates an example of a bi-directional resource case. 
         FIG. 13  is a drawing illustrating four exemplary wireless communications devices and is used to describe features of some embodiments. 
         FIG. 14  is a drawing illustrating four exemplary wireless communications devices and is used to describe features of some embodiments. 
         FIG. 15  is a flowchart of an exemplary communications method implemented in a first node in accordance with an exemplary embodiment. 
         FIG. 16  is a drawing of an exemplary communications device in accordance with an exemplary embodiment. 
         FIG. 17  is an assembly of modules which can, and in some embodiments are, used in the communications device illustrated in  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a drawing of an exemplary peer to peer communications network  100 , e.g., an ad-hoc communications network, in accordance with an exemplary embodiment. The exemplary communications network  100  supports peer to peer signaling between communication devices, e.g., mobile and/or stationary wireless communications devices. 
     Exemplary peer to peer network  100  includes a plurality of wireless peer to peer communications devices (peer to peer communications device  1   102 , peer to peer communications device  2   104 , peer to peer communications device  3   106 , peer to peer communications device  4   108 , . . . , peer to peer communications device N  110 ) supporting peer to peer signaling. In some embodiments, the network  100  includes a reference signal transmitter  112 , e.g., a beacon transmitter. The wireless devices ( 102 ,  104 ,  106 ,  108 , . . . ,  110 ) in the communications network  100  can establish connections with one another, e.g., peer to peer connections, and communicate with one another. In some embodiments, there is a recurring timing structure used in the network  100 . In some such embodiments a reference signal, e.g., an OFDM beacon signal from reference signal transmitter  112 , is used by a wireless device to synchronize with respect to the timing structure. Alternatively, a signal used to synchronize with the timing structure may be sourced from another device, e.g., a GPS transmitter, a base station or another peer to peer device. 
     Exemplary network  100  supports the spatial reuse of a wireless resource across different wireless links. In some embodiments, decisions regarding reuse of a wireless resource are performed in a decentralized manner. In various embodiments, a pair of devices of an existing connection associated with a resource, broadcast control signals having specific power relationships. The control signals are available to other connection devices, which may desire to reuse the same wireless resource, to receive and measure. The measurements are used to generate estimated SINRs upon which a resource reuse decision is based. 
       FIG. 2  is a drawing  200  illustrating four exemplary wireless communications devices (communications device A  202 , communications device B  204 , communications device C  206 , communications device D  208 ) and is used to describe features of some embodiments. In the example of  FIG. 2 , device A  202  and device B  204  have an existing connection, as indicated by solid line uni-direction arrow  210 , corresponding to currently held connection identifier  212 , which is CID=N 1 , e.g., where N 1  is an integer value in the range  1  . . .  168 . In the timing structure being utilized for the example, there is a set of air link resources associated with CID=N 1 . Devices ( 202 ,  204 ,  206 ,  208 ) are part of a peer to peer communications system in which at least some resources may be, and sometimes are, used concurrently by multiple connections, e.g., depending upon interference conditions. For example, if the first device pair (device A  202 , device B  204 ) is far away from second device pair (device C  206 , device D  208 ), then the interference levels may be sufficiently low enough that concurrent transmissions may be allowed to occur on the same air link resource. 
     In this example, device C  206  and device D  208  would like to have a connection, as indicated by dotted line arrow  214 , and would like to check if they can use the same connection identifier currently held by the device A  202 /device B  204  connection, as indicated by block  216 . In this example, we are concerned about one way communications from device A  202  to device B  204  and one way communications from device C  206  to device D  208 . Therefore, we are concerned about potential interference  220  from a device C  206  transmission impacting device B&#39;s  204  ability to successfully recover a signal from device A  202 . In such a scenario, we are also concerned about potential interference  218  from a device A  202  transmission impacting device D&#39;s  208  ability to successfully recover a signal from device C  206 . 
     In accordance with one feature of some embodiments, communications devices of existing connections transmit signals available for use by potential connection wireless devices to estimate expected SINRs should both the current connection and the potential connection use the same air link resources concurrently. In this example, communications device A  202  transmits signal S 1    250  at power level P A . Communications device B  204  transmits signal S 3    256  at power level K/(P A |h AB | 2 ), where K is a known constant and |h AB | is the magnitude of the channel gain between communications device A  202  and communications device B  204 . Device C  206  receives and measured signal S 3    256 , and estimates an expected SINR at communications device B  204  should concurrent resource usage occur. Device D  208  receives and measured signal S 3    250 , and estimates an expected SINR at communications device D  208  should concurrent resource usage occur. Based on the determined estimated SINRs, device C  206  and/or device D  208  make a decision as whether or not a connection  214  can be established using the same CID as connection  210 , e.g., both existing and new connection use CID=N 1 . In one embodiment, for the potential connection to be allowed to reuse the resource of interest, both SINRs should be equal to or greater than a threshold limit criteria, e.g., 20 dBs. 
       FIG. 3  is a drawing  300  illustrating four exemplary wireless communications devices (communications device A  302 , communications device B  304 , communications device C  306 , communications device D  308 ) and is used to describe features of some embodiments. In the example of  FIG. 3 , device A  302  and device B  304  have an existing connection, as indicated by solid line bi-directional arrow  310 , corresponding to currently held connection identifier  312 , which is CID=N 1 , e.g., where N 1  is an integer value in the range  1  . . .  168 . In the timing structure being utilized for the example, there is a set of air link resources associated with CID=N 1 . Devices ( 302 ,  304 ,  306 ,  308 ) are part of a peer to peer communications system in which at least some resources may be, and sometimes are, used concurrently by multiple connections, e.g., depending upon interference conditions. For example, if the first device pair (device A  302 , device B  304 ) is far away from second device pair (device C  306 , device D  308 ), then the interference levels may be sufficiently low enough that concurrent transmissions may be allowed to occur on the same air link resource. 
     In this example, device C  306  and device D  308  would like to have a connection, as indicated by dotted line bi-directional arrow  314 , and would like to check if they can use the same connection identifier currently held by the device A  302 /device B  304  connection, as indicated by block  316 . In this example, we are concerned about two way communications from device A  302  to device B  304  and two way communications from device C  306  to device D  308 . Bi-directional arrow  318  indicates that signals from device A  302  may cause interference to device D  308  recovery of signals from device C  306 , and that signals from device D  308  may cause interference to device A  302  recovery of signals from device B  304 . Bi-directional arrow  320  indicates that signals from device B  304  may cause interference to device C  306  recovery of signals from device D  308 , and that signals from device B  304  may cause interference to device C  306  recovery of signals from device D  308 . Bi-directional arrow  322  indicates that signals from device A  302  may cause interference to device C  306  recovery of signals from device D  308 , and that signals from device C  306  may cause interference to device A  302  recovery of signals from device B  304 . Bi-directional arrow  324  indicates that signals from device B  304  may cause interference to device D  308  recovery of signals from device C  306 , and that signals from device D  308  may cause interference to device B  304  recovery of signals from device A  302 . 
     In accordance with one feature of some embodiments, communications devices of existing connections transmit signals available for use by potential connection wireless devices to estimate expected SINRs should both the current connection and the potential connection use the same air link resources concurrently. In this example, communications device A  302  transmits signal S 1    350  at power level P A  and signal S 2    352  at power level K/(P B |h AB | 2 ), where K is a known constant and |h AB | is the magnitude of the channel gain between device A  302  and device B  304 . Communications device B  304  transmits signal S 4    354  at power level P B  and signal S 3    356  at power level K/(P A |h AB | 2 ). 
     Device C  306  receives and measures signals S 1    350 , S 2    352 , S 4    354  and S 3    356  and estimates four SINRs based on its measurements. Similarly, device D  308  receives and measures signals S 1    350 , S 2    352 , S 4    354  and S 3    356  and estimates four SINRs based on its measurements. Based on the determined estimated SINRs, device C  306  and/or device D  308  make a decision as whether or not a connection  314  can be established using the same CID as connection  310 , e.g., both existing and new connection use CID=N 1 . In one embodiment, for the potential connection to be allowed to reuse the resource of interest, each of the eight SINRs should be equal to or greater than a threshold limit criteria, e.g., 20 dBs. 
       FIG. 4 , comprising the combination of  FIG. 4A ,  FIG. 4B ,  FIG. 4C  and  FIG. 4D , is a flowchart  400  of an exemplary communications method in accordance with an exemplary embodiment. Operation starts in step  402 , where communications devices (device A, device B, device C, and device D) are powered on and initialized. Operation proceeds from step  402  to step  404  for device A; operation proceeds from step  402  via connecting device A  410  to step  412  for device B; operation proceeds from step  402  to step  418  for device C; and operation proceeds from step  402  to step  462  for device D. 
     Returning to step  404 , in step  404  device A transmits signal S 1  at power level P A  on resource R 1 . Operation proceeds from step  404  to step  406 . In step  406 , device A transmits signal S 2  at power level K/(P B |h AB | 2 ) on resource R 2 . Operation proceeds from step  406  to stop step  408 . 
     Returning to step  412 , in step  412 , device B transmits signal S 3  at power level K/(P A |h AB | 2 ) on resource R 3 . Operation proceeds from step  412  to step  414 . In step  414  device B transmits signal S 4  at power level P B  on resource R 4 . Operation proceeds from step  414  to stop step  416 . 
     Returning to step  418 , in step  418  device C receives signal S 1  on resource R 1 . Operation proceeds from step  418  to step  420 . In step  420  device C measures the received power of signal S 1  obtaining RP S1C . Then, in step  422  device C estimates an SINR at device C of a device D to device C transmission being interfered with by a device A to device B transmission, e.g., SINR ATC =P D |h CD | 2 /RP S1C . Operation proceeds from step  422  to step  424 . 
     In step  424 , device C receives signal S 2  on resource R 2 . Operation proceeds from step  424  to step  426 . In step  426  device C measures the received power of signal S 2  obtaining RP S2C . Then, in step  428  device C estimates an SINR at device A of a device B to device A transmission being interfered with by a device C to device D transmission, e.g., SINR ATA =K/(P C RP S2C ). Operation proceeds from step  428  via connecting node B  430  to step  434 . 
     In step  434 , device C receives signal S 3  on resource R 3 . Operation proceeds from step  434  to step  436 . In step  436  device C measures the received power of signal S 3  obtaining RP S3C . Then, in step  438  device C estimates an SINR at device B of a device A to device B transmission being interfered with by a device C to device D transmission, e.g., SINR ATB =K/(P C RP S3C ). Operation proceeds from step  438  to step  440 . 
     In step  440  device C receives signal S 4  on resource R 4 . Operation proceeds from step  440  to step  442 . In step  442  device C measures the received power of signal S 4  obtaining RP S4C . Then, in step  444  device C estimates an SINR at device C of a device D to device C transmission being interfered with by a device B to device A transmission, e.g., SINR ATC =P D |h CD |2/RP S4C . Operation proceeds from step  444  via connecting node D  446  to step  448 . 
     Returning to step  462 , in step  462  device D receives signal S 1  on resource R 1 . Operation proceeds from step  462  to step  464 . In step  464  device D measures the received power of signal S 1  obtaining RP S1D . Then, in step  466  device D estimates an SINR at device D of a device C to device D transmission being interfered with by a device A to device B transmission, e.g., SINR ATD =P C |h CD |2/RP S1D . Operation proceeds from step  466  to step  468 . 
     In step  468 , device D receives signal S 2  on resource R 2 . Operation proceeds from step  468  to step  470 . In step  470  device D measures the received power of signal S 2  obtaining RP S2D . Then, in step  472  device D estimates an SINR at device A of a device B to device A transmission being interfered with by a device D to device C transmission, e.g., SINR ATA =K/(P D RP S2D ). Operation proceeds from step  472  via connecting node C  474  to step  476 . 
     In step  476 , device D receives signal S 3  on resource R 3 . Operation proceeds from step  476  to step  478 . In step  478  device D measures the received power of signal S 3  obtaining RP S3D . Then, in step  480  device D estimates an SINR at device B of a device A to device B transmission being interfered with by a device D to device C transmission, e.g., SINR ATB =K/(P D RP S3D ). Operation proceeds from step  480  to step  482 . 
     In step  482  device D receives signal S 4  on resource R 4 . Operation proceeds from step  482  to step  484 . In step  484  device D measures the received power of signal S 4  obtaining RP S4D . Then, in step  486  device D estimates an SINR at device D of a device C to device D transmission being interfered with by a device B to device A transmission, e.g., SINR ATD =P C |h CD |2/RP S4D . Operation proceeds from step  486  via connecting node E  488  to step  490 . In step  490 , device D compares each of the device D estimated SINRs, e.g., results of steps  466 ,  472 ,  480  and  486 , to a threshold. If each of the device D estimated SINRs is above the threshold then operation proceeds from step  490  to step  492 ; otherwise, operation proceeds from step  490  to step  494 . 
     In step  492  device D generates a signal to device C indicating that device D&#39;s estimated SINRs meet the acceptance criteria. In step  494  device D generates a signal to device C indicating that at least one of device D&#39;s estimated SINRs does not meet the acceptance criteria. Operation proceeds from step  492  or step  494  to step  496 , in which device D transmits the generated signal of step  492  or step  494  to device C communicating the SINR comparison testing result. Operation proceeds from step  496  to step  498 . 
     Returning to step  448 , in step  448  device C compares each of the device C estimated SINRs, e.g., results of steps  422 ,  428 ,  438  and  444 , to a threshold. If each of the device C estimated SINRs is above the threshold then operation proceeds from step  448  to step  450 ; otherwise, operation proceeds from step  448  to stop step  460 . 
     Returning to step  450 , in step  450  device C receives a signal from device D communicating the SINR comparison testing result, e.g., the signal communicated in step  496 . Operation proceeds from step  450  to step  452 . In step  452  device C checks if the received signal of step  450  indicates that each of device D&#39;s estimated SINRs are above the test threshold. If each of device D&#39;s estimated SINRs are not above the test threshold, then operation proceeds from step  452  to stop step  460 ; otherwise, operation proceeds from step  452  to step  454 . 
     In step  454  device C generates a signal to device D indicating that it is ok to use the shared resource. Then, in step  456  device C transmits the generated signal to device D indicating that it is ok to use the shared resource. Operation proceeds from step  456  to step  458 . 
     Returning to step  498 , in step  498  device D is controlled to proceed from step  498  to step  499  if each of device D&#39;s estimates SINRs are above the test threshold. However, if at least one of device D&#39;s estimated SINRs is not above its test threshold, then device D is controlled to proceed from step  498  to stop step  493 . 
     Returning to step  499 , in step  499  device D monitors for a signal from device C indicating that it is ok to use the shared resource. Step  449  may, and sometimes does, include sub-step  497  in which device D receives the signal indicating that it is ok to use the shared resource. Operation proceeds from sub-step  497  to step  495  in which device D communicates with device C using the shared resource. Operation proceeds from step  495  to stop step  493 . 
     Returning to step  458 , in step  458  device C communicates with device D using the shared resource. Step  458  may be performed by device C while device D is performing step  495 . For example, device C may be transmitting to device D and device D may be receiving the transmission. A communication between device A and device B may be, and sometimes is, occurring concurrently to the communications of steps  458 / 495  using the shared resource. Operation proceeds from step  458  to stop step  460 . 
       FIG. 4  has been described above for an embodiment where each of the illustrated steps of  FIG. 4  implemented, e.g., an embodiment where resource re-usage is being considered for potential bi-directional communications such as in  FIG. 3 . However, in some embodiments, such as in  FIG. 2 , resource re-usage is considered for uni-directional links, and in one such embodiment, steps  406 ,  414   418 ,  420 ,  422 ,  424 ,  426 ,  428 ,  440 ,  442 ,  444 ,  466 ,  468 ,  470 ,  472 ,  476 ,  478 ,  480 ,  482 ,  484 ,  486 , and  497 , which are indicated by dotted boxes, may be omitted and bypassed. 
       FIG. 5 , comprising the combination of  FIG. 5A  and  FIG. 5B , is a flowchart  500  of an exemplary method of operating a first node in accordance with an exemplary embodiment. The exemplary first node is, e.g., exemplary communications device C  206  of  FIG. 2  or exemplary communications device C  306  of  FIG. 3 . In one embodiment where the exemplary first node is device C  206  of  FIG. 2 , steps  510 ,  512 ,  514 ,  516 ,  518 ,  520 ,  524 ,  526  and  528  are omitted and bypassed. In one embodiment where the exemplary first node is device C  306  of  FIG. 3 , steps  510 ,  512 ,  514 ,  516 ,  518 ,  520 ,  524 ,  526  and  528  are included in the method. The exemplary first node may be one of the peer to peer communications devices of network  100  of  FIG. 1 . Operation starts in step  502 , where the first node is powered on and initialized. Operation proceeds from start step  502  to step  504 . 
     In step  504  the first node receives a first signal from a second node, e.g., signal S 3    256  from device B  204  or signal S 3    356  from device B  304 . In some embodiments, the first signal is a signal which was transmitted by the second node at a power level inversely proportional to a power level of signal received from a third node, e.g., node A  202  or node A  302 . Operation proceeds from step  504  to step  506 . In step  506  the first node measures the received power of the first signal, e.g. obtaining RP S3C . Then in step  508  the first node estimates a first SINR at the second node for a transmission from a third node to the second node in the presence of a transmission from the first node to a fourth node, e.g., node D  208  or node D  308 , using a resource also used for the transmission from the third node to the second node. The first estimated SINR is, e.g., SINR ATB =K/(P C RP S3C ). Operation proceeds from step  508  to step  510 . 
     In step  510 , the first node receives a second signal from the third node, e.g. signal S 1    350  from device A  302 . Operation proceeds from step  510  to step  512 . In step  512  the first node measures the received power of the second signal, e.g., obtaining RP S1C . Then in step  514 , the first node estimates a second SINR at the first node for a transmission from the fourth node to the first node in the presence of a transmission from the third node to the second node using a resource also used for the transmission from the first node to the fourth node. The second estimated SINR is, e.g., SINR ATC =P D |h CD | 2 /RP S1C . Operation proceeds from step  514  to step  516 . 
     In step  516  the first node receives a third signal from the third node, e.g., signal S 2    352  from device A  302 . Operation proceeds from step  516  to step  518 . In step  518  the first node measures the received power of the third signal, e.g., obtaining RP S2C . Then, in step  520  the first node estimates a third SINR at the third node for a transmission from the second node to the third node in the presence of a transmission from the first node to the fourth node using a resource also used for the transmission from the second node to the third node. The third estimated SINR is, e.g., SINR ATA =K/(P C RP S2C ). Operation proceeds from step  520  via connecting node A  522  to step  524 . 
     In step  524  the first node receives a fourth signal from the second node, e.g., signal S 4    354  from device B  304 . Operation proceeds from step  524  to step  526 . In step  526  the first node measures the received power of the fourth signal, e.g., obtaining RP S4C . Then, in step  528  the first node estimates a fourth SINR at the first node for a transmission from the fourth node to the first node in the presence of a transmission from the second node to the third node using a resource also used for the transmission from the fourth node to the first node. The fourth estimated SINR is, e.g., SINR ATC =P D |h CD | 2 /RP S4C . Operation proceeds from step  528  to step  530 . 
     In step  530  the first node receives SINR level information from the fourth node. The received SINR level information includes, e.g., an SINR level and/or an indicator that an SINR determined by the fourth node exceeded a threshold level. In some embodiments, the received SINR level information is an indication as to whether or not each member of set of estimated SINRs calculated at the fourth node is above a threshold limit. For an embodiment, where one-way direction concurrent communication links are being considered using the same air link resource as in  FIG. 2 , the set is, e.g., a set of one SINR measurement. For an embodiment, where two way direction communications links are being considered using the same air link resource as in  FIG. 3 , the set is, e.g., a set of four SINRs. In some embodiments, the received SINR level information is a set of estimated SINRs calculated by the fourth node. In some embodiments, the received SINR level information is a connection identifier candidate list that may indicate exceeding SINR thresholds corresponding to CIDs on the candidate list. Operation proceeds from step  530  to step  532 . 
     In step  532  the first node decides, based on the first estimated SINR, whether to communicate with the fourth node using said resource. Step  532  includes sub-steps  534  and  542 . In some embodiments, step  532  also includes sub-steps  536 ,  538  and  540 . 
     In sub-step  534 , the first node determines whether the first estimated SINR exceeds a first SINR threshold level. In sub-step  536 , the first node determines whether the second estimated SINR exceeds a second SINR threshold level. In some embodiments, deciding whether or not to communicate with the fourth node is also based on the second estimated SINR. In sub-step  538 , the first node determines whether the third estimated SINR exceeds a third SINR threshold level. In sub-step  540 , the first node determines whether the fourth estimated SINR exceeds a fourth SINR threshold level. In some embodiments, deciding whether to communicate with the fourth node using said resource is also based on each of the estimated third and fourth SINRs. In some embodiments, the first, second, third and fourth estimated SINR levels are the same value. 
     In sub-step  542  the first node determines whether the SINR level information from the fourth node indicates that it is acceptable for the first node to communicate with the fourth node. In some embodiments the determination of step  542  includes recovering a pass/fail indicator from the received SINR level information of step  530 . In some other embodiments, the determination of step  542  includes comparing a set of received SINRs communicated in SINR level information received in step  530  to SINR threshold level criteria. In various embodiments, deciding whether or not to communicate with the fourth node is also based on the received SINR level information of step  530 . 
     In some embodiments, deciding whether to communicate with the fourth node using said resource includes deciding to communicate when said first estimated SINR exceeds a first threshold level and said received SINR level information indicates a SINR over a second threshold or that the fourth node has determined that an SINR determined at the fourth node exceeds a second threshold. In some embodiments, the second threshold is the same first threshold used by the first node. 
     In some but not all embodiments, the same SINR threshold is used throughout the system for resource reuse decisions. In other embodiments, different SINR thresholds, used for resource reuse decisions, are associated with different nodes. In some embodiments, different SINR thresholds, used for resource reuse decisions, are associated with different connections. In some embodiments, a device uses different SINR thresholds for resource reuse decisions corresponding to different devices and/or connections. 
       FIG. 6  is a drawing of an exemplary communications device  600  in accordance with an exemplary embodiment. Exemplary communications device  600  is, e.g., communications device C  206  of  FIG. 2  or communications device C  306  of  FIG. 3 . Exemplary communications device  600  may be one of the exemplary peer to peer communications devices of network  100  of  FIG. 1 . Exemplary communications device  600  implements a method in accordance with flowchart  500  of  FIG. 5 . 
     Communications device  600  includes a processor  602  and memory  604  coupled together via a bus  609  over which the various elements ( 602 ,  604 ) may interchange data and information. Communications device  600  further includes an input module  606  and an output module  608  which may be coupled to processor  602  as shown. However, in some embodiments, the input module  606  and output module  608  are located internal to the processor  602 . Input module  606  can receive input signals. Input module  606  can, and in some embodiments does, include a wireless receiver and/or a wired or optical input interface for receiving input. Output module  608  may include, and in some embodiments does include, a wireless transmitter and/or a wired or optical output interface for transmitting output. 
     Processor  602  is configured to receive a first signal from a second node; measure the received power of the first signal; estimate a first SINR at the second node for a transmission from a third node to the second node in the presence of a transmission from the first node to a fourth node using a resource also used for the transmission from the third node to the second node; and decide based on the first estimated SINR whether to communicate with the fourth node using said resource. In some embodiments, said first signal is a signal which was transmitted by the second node at a power level inversely proportional to a power level of a signal received from the third node. In some embodiments, processor  602  is configured to determine if the estimated SINR exceeds a first SINR threshold level as part of being configured to decide based on the estimated SINR. 
     In some embodiments, processor  602  is further configured to: receive SINR level information from the fourth node; and being configured to decide whether to communicate with the fourth node includes being configured to base the decision on the received SINR level information. 
     In various embodiments, being configured to decide based on the estimated SINR whether to communicate includes being configured to decide to communicate when said estimated SINR exceeds a first threshold level and said received SINR level information indicates a SINR over a second threshold or that the fourth node has determined that an SINR determined at the fourth node exceeds a second threshold Tin some embodiments, the second threshold may be the same as the first threshold used by the first node. 
     In some embodiments, processor  602  is configured to: receive a second signal from a third node; measure the received power of the second signal; estimate a second SINR at the first node for a transmission from the fourth node to the first node in the presence of a transmission from the third node to a second node using a resource also used for the transmission from the first node to the fourth node; and being configured to decide whether to communicate with the fourth node using said resource also includes being configured to decide based on the second estimated SINR. 
     Processor  602 , in some embodiments, is configured to: receive a third signal from the third node; measure the received power of the third signal; and estimate a third SINR at the third node for a transmission from a second node to the third node in the presence of a transmission from first node to a fourth node using a resource also used for the transmission from the second node to the third node. In some such embodiments, processor  602  is further configured to: receive a fourth signal from a second node; measure the received power of the fourth signal; and estimate a fourth SINR at the first node for a transmission from a fourth node to the first node in the presence of a transmission from second node to a third node using a resource also used for the transmission from the fourth node to the first node. In various embodiments, being configured to decide whether to communicate with the fourth node using said resource includes being configured to base the decision on each of the estimated third and fourth SINRs. 
       FIG. 7  is an assembly of modules  700  which can, and in some embodiments are, used in the communications device  600  illustrated in  FIG. 6 . The modules in the assembly  700  can be implemented in hardware within the processor  602  of  FIG. 6 , e.g., as individual circuits. Alternatively, the modules may be implemented in software and stored in the memory  604  of the communications device  600  shown in  FIG. 6 . While shown in the  FIG. 6  embodiment as a single processor, e.g., computer, it should be appreciated that the processor  602  may be implemented as one or more processors, e.g., computers. When implemented in software the modules include code, which when executed by the processor, configure the processor, e.g., computer,  602  to implement the function corresponding to the module. In embodiments where the assembly of modules  700  is stored in the memory  604 , the memory  604  is a computer program product comprising a computer readable medium comprising code, e.g., individual code for each module, for causing at least one computer, e.g., processor  602 , to implement the functions to which the modules correspond. 
     Completely hardware based or completely software based modules may be used. However, it should be appreciated that any combination of software and hardware (e.g., circuit implemented) modules may be used to implement the functions. As should be appreciated, the modules illustrated in  FIG. 7  control and/or configure the communications device  600  or elements therein such as the processor  602 , to perform the functions of the corresponding steps illustrated in the method flowchart  500  of  FIG. 5 . 
     As illustrated in  FIG. 7 , the assembly of modules  700  includes: a module  704  for receiving a first signal from a second node, a module  706  for measuring the received power of the first signal, a module  708  for estimating a first SINR at the second node for a transmission from a third node to the second node in the presence of a transmission from the first node to a fourth node using a resource also used for transmission from the third node to the second node, a module  730  for receiving SINR level information from the fourth node, and a module  732  for deciding, based on the first estimated SINR, whether to communicate with the fourth node using said resource. 
     In some embodiments, assembly of modules  700  includes one or more of: a module  710  for receiving a second signal from the third node, a module  712  for measuring the received power of the second signal, a module  714  for estimating a second SINR at the first node for a transmission from the fourth node to the first node in the presence of a transmission from the third node to the second node using a resource also used for the transmission from the first node to the fourth node, a module  716  for receiving a third signal from the third node, a module  718  for measuring the received power of the third signal, a module  720  for estimating a third SINR at the third node for a transmission from the second node to the third node in the presence of a transmission from the first node to the fourth node using a resources also used for the transmission from the second node to the third node, a module  724  for receiving a fourth signal from the second node, a module  726  for measuring the received power of the fourth signal, and a module  728  for estimating a fourth SINR at the first node for a transmission from the fourth node to the first node in the presence of a transmission from the second node to the third node using a resource also used for the transmission from the fourth node to the first node. 
     Module  732  includes a module  734  for determining whether the first estimated SINR exceeds a first SINR threshold level and a module  742  for determining whether the SINR information from the fourth node indicates that it is acceptable for the first node to communicate with the fourth node. In some embodiments module  732  further includes one or more of: a module  736  for determining whether the second estimated SINR exceeds a second SINR threshold level, a module  738  for determining whether the third estimated SINR exceeds a third SINR threshold level and a module  740  for determining whether the fourth estimated SINR exceeds a fourth SINR threshold level. 
     In some embodiments, the first signal is a signal which was transmitted by the second node at a power level inversely proportional to a power level of a signal received from the third node. In various embodiments, the module  732  for deciding, based on the first estimated SINR, whether to communicate with the fourth node using said resource decides to communicate when said first estimated SINR exceeds a first threshold level and said received SINR level information indicates a SINR over a second threshold or that the fourth node has determined that an SINR determined at the fourth node exceeds a second threshold level. In some embodiments, the second threshold level is the same as the first threshold level used by the first node. 
     The module  732  for deciding whether to communicate with the fourth node using said resource, in some embodiments, also bases its decision on the second estimated SINR. The module  732  for deciding whether to communicate with the fourth node using said resource, in some embodiments, bases its decision on each of the estimated third and fourth SINRs. 
       FIG. 8 , comprising the combination of  FIG. 8A  and  FIG. 8B , is a flowchart  800  of an exemplary method of operating a first node in accordance with an exemplary embodiment. The exemplary first node is, e.g., communications device D  208  of  FIG. 2  or communications device D  308  of  FIG. 3 . In one embodiment where the exemplary first node is device D  208  of  FIG. 2 , steps  810 ,  812 ,  814 ,  816 ,  818 ,  820 ,  824 ,  826  and  828  are omitted and bypassed. In one embodiment where the exemplary first node is device D  308  of  FIG. 3 , steps  810 ,  812 ,  814 ,  816 ,  818 ,  820 ,  824 ,  826  and  828  are included in the method. The first node may be one of the exemplary peer to peer communications devices of network  100  of  FIG. 1 . Operation starts in step  802  where the first node is powered on and initialized and proceeds to step  804 . In step  804  the first node receives a first signal from a second node, e.g., signal S 1    250  from device A  202  or signal S 1    350  from device A  302 . In some embodiments, the first signal is a signal which was transmitted by the second node at a predetermined power level, e.g., P A . Operation proceeds from step  804  to step  806 . In step  806  the first node measures the received power of the first signal, e.g., obtaining RP S1D . Then in step  808  the first node estimates a first SINR at the first node for a transmission from the third node to the first node in the presence of a transmission from the second node to a fourth node using a resource also used for the transmission from the third node to the first node. The third node is, e.g., device C  206  of  FIG. 2  or device C  306  of  FIG. 3 . The fourth node is, e.g., device B  204  of  FIG. 2  or device B  304  of  FIG. 3 . The first estimated SINR is, e.g., SINR ATD =P C |h CD | 2 /RP S1D . Operation proceeds from step  808  to step  810 . 
     In step  810  the first node receives a second signal from the second node, e.g., signal S 2    352  from device A  302 . Operation proceeds from step  810  to step  812 . In step  812  the first node measures the received power of the second signal, e.g., obtaining RP S2D . Then in step  814  the first node estimates a second SINR at the second node for a transmission from the fourth node to the second node in the presence of a transmission from the first node to the third node using a resource also used for the transmission from the second node to the fourth node. The second estimated SINR is, e.g., SINR ATA =K/(P D RP S2D ). Operation proceeds from step  814  to step  816 . 
     In step  816  the first node receives a third signal from the fourth node, e.g., signal S 3    356  from device B  304 . Operation proceeds from step  816  to step  818 . In step  818  the first node measures the received power of the third signal, e.g., obtaining RP S3D . Then, in step  820  the first node estimates a third SINR at the fourth node for a transmission from the second node to the fourth node in the presence of a transmission from the first node to the third node using a resource also used for the transmission from the second node to the fourth node. The third estimated SINR is, e.g., SINR ATB =K/(P D RP S3D ). Operation proceeds from step  820  via connecting node A  822  to step  824 . 
     In step  824  the first node receives a fourth signal from the fourth node, e.g., signal S 4    354  from node B  304 . Operation proceeds from step  824  to step  826 . In step  826  the first node measures the received power of the fourth signal, e.g., obtaining RP S4D . Then in step  828  the first node estimates a fourth SINR at the first node for a transmission from the third node to the first node in the presence of a transmission from the fourth node to the second node using a resource also used for the transmission from the third node to first node. The fourth estimated SINR is, e.g., SINR ATD =P C |h CD | 2 /RP S4D . Operation proceeds from step  828  to step  830 . 
     In step  830  the first node receives SINR level information from the third node. The received SINR level information includes, e.g., a SINR level and/or an indicator. For example one or more SINR levels determined by the third node are communicated to the first node. As another example, an indicator is communicated from the third node to the first node indicating that a set of third node estimated SINRs are above threshold criteria. 
     In one case where uni-direction concurrent transmission are under consideration as with the example of  FIG. 2 , in some embodiments, one SINR value is communicated in the received SINR information or an indicator is communicated indicating whether one third node estimated SINR exceeded a threshold criteria. In another case where concurrent transmission in the same or different directions are under consideration as with the example of  FIG. 3 , in some embodiments, multiple, e.g., four, SINR values may be, and sometimes are communicated, in the received SINR information or an indicator is communicated indicating whether each of the multiple, e.g., each of the four, third node estimated SINRs exceeded threshold criteria. 
     In still another case a CID candidate list may be communicated from the third node to the first node indicating those CIDs for which estimated SINR were tested and which exceeded the threshold criteria. 
     Operation proceeds from step  830  to step  832 . In step  832  the first node decides, based on the first estimated SINR, whether to communicate with the third node using said resource. Step  832  includes sub-steps  834  and  842 . In some embodiments, step  832  also includes sub-steps  836 ,  838  and  840 . In sub-step  834  the first node determines whether the first estimated SINR exceeds a first SINR threshold level. In sub-step  836  the first node determines whether the second estimated SINR exceeds a second SINR threshold level. In some embodiments, deciding whether to communicate with the third node using said resource is also based on the second estimated SINR. In sub-step  838  the first node determines whether the third estimated SINR exceeds a third SINR threshold level. In sub-step  840  the first node determines whether the fourth estimated SINR exceeds a fourth SINR threshold level. In some embodiments, deciding whether to communicate with the third node using said resource is also based on each of the estimated third and fourth SINRs. 
     In some embodiments, the first, second, third and fourth SINR threshold levels are the same value. In sub-step  842  the first node determines whether the SINR level information from the third node indicates that it is acceptable for the third node to communicate with the first node. In some embodiments, the same SINR threshold level criteria is used by both the first and third nodes. In some other embodiments, different SINR threshold level criteria are used by the first and third nodes. 
     In some embodiments, deciding whether to communicate with the third node using said resource includes deciding to communicate when the estimated SINR exceeds a first threshold and said received SINR level information indicates a SINR over a second threshold or that the third node has determined that an SINR determined at the third node exceeds a second threshold. The second threshold, in some embodiments, is the same as the first threshold used by the first node. 
     In some but not all embodiments, the same SINR threshold is used throughout the system for resource reuse decisions. In other embodiments, different SINR thresholds, used for resource reuse decisions, are associated with different nodes. In some embodiments, different SINR thresholds, used for resource reuse decisions, are associated with different connections. In some embodiments, a device uses different SINR thresholds for resource reuse decisions corresponding to different devices and/or connections. 
       FIG. 9  is a drawing of an exemplary communications device  900  in accordance with an exemplary embodiment. Exemplary communications device  900  is, e.g., communications device D  208  of  FIG. 2  of communications device D  308  of  FIG. 3 . Communications device  900  may be one of the exemplary peer to peer communications devices of network  100  of  FIG. 1 . Exemplary communications device  900  implements a method in accordance with flowchart  800  of  FIG. 8 . 
     Communications device  900  includes a processor  902  and memory  904  coupled together via a bus  909  over which the various elements ( 902 ,  904 ) may interchange data and information. Communications device  900  further includes an input module  906  and an output module  908  which may be coupled to processor  902  as shown. However, in some embodiments, the input module  906  and output module  908  are located internal to the processor  902 . Input module  906  can receive input signals. Input module  906  can, and in some embodiments does, include a wireless receiver and/or a wired or optical input interface for receiving input. Output module  908  may include, and in some embodiments does include, a wireless transmitter and/or a wired or optical output interface for transmitting output. 
     Processor  902  is configured to receive a first signal from a second node; measure the received power of the first signal; estimate a first SINR at the first node for a transmission from a third node to the first node in the presence of a transmission from a second node to a fourth node using a resource also used for the transmission from the third node to the first node; and decide based on the estimated SINR whether to communicate with the third node using said resource. In some embodiments, said first signal is a signal which was transmitted by the second node at a predetermined power level. In some embodiments, processor  902  is configured to determine if the first estimated SINR exceeds a first SINR threshold level as part of being configured to decide based on the estimated SINR. 
     In some embodiments, processor  902  is configured to receive SINR level information from the third node. In some such embodiments, processor  902  is configured, as part of being configured to decide whether to communicate with the third node, to base its decision on the received SINR level information. 
     In some embodiments, being configured to decide based on the estimated SINR whether to communicate includes being configured to decide to communicate when said estimated SINR exceeds a first threshold level and said received SINR level information indicates a SINR over a second threshold or that the third node has determined that an SINR determined at the third node exceeds a second threshold. The second threshold may be, and sometimes is, the same as the first threshold used by the first node. 
     Processor  902 , in some embodiments, is configured to: receive a second signal from a second node; measure the received power of the second signal; and estimate a second SINR at the second node for a transmission from the fourth node to the second node in the presence of a transmission from the first node to a third node using a resource also used for the transmission from the second node to the fourth node. In some such embodiments, processor  902 , as part of being configured to decide whether to communicate with the third node, is configured to base its decision on the second estimated SINR. 
     In some embodiments, processor  902  is configured to: receive a third signal from the fourth node; measure the received power of the third signal; and estimate a third SINR at the fourth node for a transmission from a second node to the fourth node in the presence of a transmission from first node to a third node using a resource also used for the transmission from the second node to the fourth node. In some such embodiments, processor  902  is further configured to: receive a fourth signal from a fourth node; measure the received power of the fourth signal; and estimate a fourth SINR at the first node for a transmission from a third node to the first node in the presence of a transmission from fourth node to a second node using a resource also used for the transmission from the third node to the first node. In some such embodiments, being configured to decide whether to communicate with the third node using said resource includes being configured to base the decision on each of the estimated third and fourth SINRs. 
       FIG. 10  is an assembly of modules  1000  which can, and in some embodiments are, used in the communications device  900  illustrated in  FIG. 9 . The modules in the assembly  1000  can be implemented in hardware within the processor  902  of  FIG. 9 , e.g., as individual circuits. Alternatively, the modules may be implemented in software and stored in the memory  904  of the communications device  900  shown in  FIG. 9 . While shown in the  FIG. 9  embodiment as a single processor, e.g., computer, it should be appreciated that the processor  902  may be implemented as one or more processors, e.g., computers. When implemented in software the modules include code, which when executed by the processor, configure the processor, e.g., computer,  902  to implement the function corresponding to the module. In embodiments where the assembly of modules  1000  is stored in the memory  904 , the memory  904  is a computer program product comprising a computer readable medium comprising code, e.g., individual code for each module, for causing at least one computer, e.g., processor  902 , to implement the functions to which the modules correspond. 
     Completely hardware based or completely software based modules may be used. However, it should be appreciated that any combination of software and hardware (e.g., circuit implemented) modules may be used to implement the functions. As should be appreciated, the modules illustrated in  FIG. 10  control and/or configure the communications device  900  or elements therein such as the processor  902 , to perform the functions of the corresponding steps illustrated in the method flowchart  800  of  FIG. 8 . 
     Assembly of modules  1000  includes: a module  1004  for receiving a first signal from a second node, a module  1006  for measuring the received power of the first signal, a module  1008  for estimating a first SINR at the first node for a transmission from a third node to the first node in the presence of a transmission from the second node to a fourth node using a resource also used for the transmission from the third node to the first node, a module  1030  for receiving SINR level information from the fourth node, and a module  1032  for deciding, based on the first estimated SINR, whether to communicate with the third node using said resource. 
     In some embodiments, assembly of modules  1000  includes a module  1010  for receiving a second signal from the second node, a module  1012  for measuring the received power of the second signal, a module  1014  for estimating a second SINR at the second node for a transmission from the fourth node to the second node in the presence of a transmission from the first node to third node using a resource also used for the transmission from the second node to the fourth node, a module  1016  for receiving a third signal from the fourth node, a module  1018  for measuring the received power of the third signal, a module  1020  for estimating a third SINR at the fourth node for a transmission from a second node to the fourth node in the presence of a transmission from the first node to the third node using a resource also used for the transmission from the second node to the fourth node, a module  1024  for receiving a fourth signal from a fourth node, a module  1026  for measuring the received power of the fourth signal, and a module  1028  for estimating a fourth SINR at the first node for a transmission from the third node to the first node in the presence of a transmission from the fourth node to the second node using a resource also used for the transmission from the third node to the first node. 
     Module  1032  includes a module  1034  for determining whether the first estimated SINR exceeds a first SINR threshold level and a module  1042  for determining whether the SINR level information from the fourth node indicates that it is acceptable for the first node to communicate with the fourth node. In some embodiments, module  1032  further includes one or more of: a module  1036  for determining whether the second estimated SINR exceeds a second SINR threshold level, a module  1038  for determining whether the third estimated SINR exceeds a third SINR threshold level and a module  1040  for determining whether the fourth estimated SINR exceeds a fourth SINR threshold level. 
     In some embodiments, the first signal is a signal which was transmitted by the second node at a predetermined power level. In various embodiments, the module  1032  for deciding, based on the first estimated SINR, whether to communicate with the third node using said resource decides to communicate when said first estimated SINR exceeds a first threshold level and said received SINR level information indicates a SINR over a second threshold or that the third node has determined that an SINR determined at the SINR exceeds a second threshold level. In some embodiments, the second threshold level is the same as the first threshold level used by the first node. 
     The module  1032  for deciding whether to communicate with the third node using said resource, in some embodiments, also bases its decision on the second estimated SINR. The module  1032  for deciding whether to communicate with the third node using said resource, in some embodiments, bases its decision on each of the estimated third and fourth SINRs. 
     Various features and/or aspects relating to some embodiments will now be described. One problem that some embodiments address is that of facilitating spatial reusing of a given wireless resource across different wireless links. Consider an example of two links A-B and C-D. One may like to determine whether these links should reuse a given wireless resource simultaneously. The criterion for reusing the resource, in some embodiments, includes evaluating expected SINR seen for each of the links. Now consider that the links are uni-directional links, e.g., a A-&gt;B link and A C-&gt;D link, and consider that the uni-directional links are to reuse the resource simultaneously, then the SINR seen by A-&gt;B would be 
                   P   A     ⁢            h   AB          2           P   C     ⁢            h   BC          2         ,         
and the SINR seen by C-&gt;D would be
 
                   P   C     ⁢            h   CD          2           P   A     ⁢            h   AD          2         .         
One would like to know that both these SINRs are expected to be above a certain threshold, e.g., 20 db, for them to reuse the resource.
 
     In one approach, a two block broadcast structure is implemented. If a certain link is using a certain wireless resource, e.g., it is an established link having an associated CID, then we use a control channel where the link broadcasts information. In some embodiments, the number of tones used for the control channel is at least twice the number of available wireless resources. A link using a particular wireless resource transmits energy on two of those tones. The two tones are dedicated for that wireless resource. In some embodiments, a multiple of such two tones may be, and sometimes are, dedicated for a given wireless resource. 
     On a first one of the tones the energy is proportional to the power used by the transmitter and the energy is sent by the transmitter. Consider that node A transmits on the first tone with power level P A . This information is used by the receivers of other wireless links potentially interested in reusing the resource to calculate the SINR that the link will see due to the presence of the first link. A link interested in reusing the resource will determine that the estimated SINR is at least a threshold limit, e.g., at least 20 db, before reusing the link. 
     For example, consider that A-&gt;B is an active connection. Further consider that C-&gt;D connection is trying to decide whether to reuse the resource. Device D measures the received power, e.g., obtaining P A |h AD | 2 , and determines if 
                 P   C     ⁢            h   CD          2           P   A     ⁢            h   AD          2             
is at least a threshold limit, e.g., at least 20 db. This test condition should be satisfied to allow reuse of the link. It should be noted that D knows P C |h CD | 2 .
 
     On a second one of the tones the energy is inversely proportional to the power received by the receiver and the energy is sent by the receiver of the active link. Consider that node B transmits on the second one of the tones at power level K/(P A |h AB | 2 ), where K is a known constant. This information is used by the transmitters of other wireless links potentially interested in reusing the resource to calculate the estimated SINR that the existing link will see due to the new link. A new links will verify that the estimated SINR is at least a threshold limit, e.g., at least 20 db for the existing link before reusing the link. 
     C measures the received power of the signal on the second one of the tones which is (K|h BC | 2 )/(P A |h AB | 2 ) and uses that information to determine if 
                 P   A     ⁢            h   AB          2           P   C     ⁢            h   BC          2             
is at least a threshold limit, e.g., at least 20 db. This condition should be satisfied to allow reuse of the resource by the new link. The energy measured by C when B transmits is proportional to
 
                        h   BC          2         P   A     ⁢            h   AB          2         ,         
and the value K is known. C also knows P C . In some embodiments, for the new link C-&gt;D to be allowed to reuse the resource of existing link A-&gt;B, both the first estimated SINR test performed by device D and the second estimated SINR test performed by device C, should both pass, e.g., both estimated SINRs are at least 20 dBs.
 
       FIG. 11  includes drawing  1100  which illustrates an example of a uni-directional resource case. Communications device A  1102  and communications device B  1104  are nodes of an existing active connection A-&gt;B which has an associated uni-direction resource for communicating data and/or information in the direction from device A to device B. Communications device C  1106  and communications device D  1108  are nodes of a potential connection C-&gt;D which would like to simultaneously use the A-&gt;B uni-direction resource for communicating data and/or information in the direction from device C to device D. There are channels between the various combinations of device pairs (h AB    1110 , h AC    1112 , h AD    1114 , h BC    1116 , h BD    1118 , h CD    1120 ). 
     Communications device A  1102  transmits a control signal  1126  at power level P A  which is received and measured by communications device D  1108 . Communications device D  1108 , which knows the channel h CD    1120  and power level P C , uses the measured information to calculate an expected SINR at device D should a transmission from device C to device D occur in the presence of a transmission from device A to device B using the shared resource of interest. The estimated SINR is compared to a threshold value. 
     Communications device B  1104  transmits a control signal  1128  at power level=K/(P A |h AB | 2 ) which is received and measured by communications device C  1106 . Communications device C  1106 , which knows the channel h CD    1120 , power level P C , and value of constant K, uses the measured information to calculate an expected SINR at device B should a transmission from device A to device B occur in the presence of a transmission from device C to device D using the shared resource of interest. The estimated SINR is compared to a threshold criteria. If both the device C estimated SINR and the device D estimated SINR are greater than or equal to the threshold value then the C-&gt;D connection is allowed to use the resource. 
     Devices ( 1102 ,  1104 ,  1106 ,  1108 ) of  FIG. 11  are, e.g., devices ( 202 ,  204 ,  206 ,  208 ) of  FIG. 2 . In  FIG. 2 , resource reusage is described in the context of a connection identifier with associated resources. In general, the methods and apparatus of various embodiments are also applicable to other resources, e.g., a traffic segment under contention. 
     The approach described above for a uni-direction resource can be extended to a bi-directional resource. 
     If the resource being potentially reused can be used by a wireless link in both directions, then a similar but modified approach can be implemented. In this case, in the control channel each device of the existing active connection sends energy on two tones. Thus a total of four tones are used to send control signals used to estimate SINRs. For each active connection device, the energy in one of the tones is proportional to power used by the device to transmit, and the energy in the other tone is inversely proportional to power received from the other device of its connection. These quantities are used to estimate that for each of the various combinations possible, which are a total of 8, the SINR is at least a predetermined limit value, e.g., at least 20 dbs. 
     Consider an example, where A&lt;- -&gt;B is an active connection, and C&lt;- -&gt;D is trying to reuse the resource. Consider that node A transmits a control signal on a first tone at power level P A  and that node B transmits a control signal on second tone at power level P B . Device C and device D receive the transmitted signals, estimate SINRs and test the SINRs to a threshold. 
     C estimates SINRs and verifies that
         min(P D *|h CD | 2 /(P A *|h AC | 2 ), P D *|h CD | 2 /(P B *|h BC | 2 )) is &gt; a threshold limit, e.g., &gt;20 db       

     D estimates SINRs and verifies that
         min(P C *|h CD | 2 /(P A *|h AD | 2 ), P C *|h CD | 2 /(P B *|h BD | 2 ))&gt;a threshold limit, e.g., &gt;20 db       

     Further consider that node A transmits a control signal on a third tone at power level K/(P B |h AB | 2 ) and that node B transmits a control signal on fourth tone at power level K/(P A |h AB | 2 ). Device C and device D receive the transmitted signals, estimate SINRs and test the SINRs to a threshold. 
     C estimates SINRs and verifies that
         min(P A *|h AB | 2 /(P C *|h BC | 2 ), P B *|h AB | 2 /(P C *|h AC | 2 )) is &gt;a threshold value, e.g., &gt;20 db       

     D estimates SINRs and verifies that
         min(P A *|h AB | 2 /(P D *|h BD | 2 ), P B *|h AB | 2 /(P D *|h AD | 2 )) is &gt;a threshold value, e.g., &gt;20 dB.       

       FIG. 12  includes drawing  1200  which illustrates an example of a bi-directional resource case. Communications device A  1202  and communications device B  1204  are nodes of an existing active connection A&lt;- -&gt;B which has an associated bi-direction resource for communicating data and/or information between devices A and B in either direction. Communications device C  1206  and communications device D  1208  are nodes of a potential connection C&lt;- -&gt;D which would like to simultaneously use the A&lt;- -&gt;B bi-direction resource for communicating data and/or information between device C and device D in either direction. There are channels between the various combinations of device pairs (h AB    1210 , h AC    1212 , h AD    1214 , h BC    1216 , h BD    1218 , h CD    1220 ). 
     Communications device A  1202  generates and transmits control signal with power level P A    1226  and a control signal with power level K/(P B |h AB | 2 )  1227 . Communications device B  1204  generates and transmits control signal with power level P B    1229  and a control signal with power level K/(P A |h AB | 2 )  1228 . Device C  1202  and device D  1208  receive and measure the transmitted control signals ( 1226 ,  1227 ,  1229 ,  1228 ). Devices C  1202 , which know the power levels P C , P D , h CD  and the value of constant K, uses its measurements of control signals to calculate four estimated SINRs should concurrent use of the resource of interest occur. The estimated SINRs are compared to a threshold criteria value. Devices D  1208 , which knows the power levels P C , P D , h CD  and the value of constant K, uses its measurements of control signals to calculate four estimated SINRs should concurrent use of the resource of interest occur. The estimated SINRs are compared to a threshold criteria value. If each of eight estimated SINRs are equal to or greater than the threshold criteria value, e.g., 20 dBs, then potential connection C&lt;- -&gt;D is allowed to use the resource of interest concurrently with the A&lt;- -&gt;B connection. 
     Devices ( 1202 ,  1204 ,  1206 ,  1208 ) of  FIG. 12  are, e.g., devices ( 302 ,  304 ,  306 ,  308 ) of  FIG. 3 . In  FIG. 3 , resource reusage is described in the context of a connection identifier with associated air link resources. In general the methods and apparatus of various embodiments are also applicable to other resources, e.g., a traffic segment under contention. 
       FIG. 13  is a drawing  1300  illustrating four exemplary wireless communications devices (communications device A  1302 , communications device B  1304 , communications device C  1306 , communications device D  1308 ) and is used to describe features of some embodiments. In the example of  FIG. 13 , device A  1302  and device B  1304  have an existing connection, as indicated by solid line uni-direction arrow  1310 , corresponding to currently held connection identifier  1312 , which is CID=N 1 , e.g., where N 1  is an integer value in the range  1  . . .  168 . In the timing structure being utilized for the example, there is a set of air link resources associated with CID=N 1 . Devices ( 1302 ,  1304 ,  1306 ,  1308 ) are part of a peer to peer communications system in which at least some resources may be, and sometimes are, used concurrently by multiple connections, e.g., depending upon interference conditions. For example, if the first device pair (device A  1302 , device B  1304 ) is far away from second device pair (device C  1306 , device D  1308 ), then the interference levels may be sufficiently low enough that concurrent transmissions may be allowed to occur on the same air link resource. Devices ( 1302 ,  1304 ,  1306 ,  1308 ) are, e.g., peer to peer devices of network  100  of  FIG. 1 . 
     In this example, device C  1306  and device D  1308  would like to have a connection, as indicated by dotted line arrow  1314 , and would like to check if they can use the same connection identifier currently held by the device A  1302 /device B  1304  connection, as indicated by block  1316 . In this example, we are concerned about one way communications from device A  1302  to device B  1304  and one way communications from device C  1306  to device D  1308 . Therefore, we are concerned about potential interference from a device C  1306  transmission impacting device B&#39;s  1304  ability to successfully recover a signal from device A  1302 . In such a scenario, we are also concerned about potential interference from a device A  1302  transmission impacting device D&#39;s  1308  ability to successfully recover a signal from device C  1306 . 
     In accordance with one feature of some embodiments, communications devices of existing connections transmit control signals available for use by potential connection wireless devices to estimate expected SINRs should both the current connection and the potential connection use the same air link resources concurrently. In this example, communications device A  1302  transmits control signal S 3    1322  at power level P AC1 . Communications device B  1304  transmits control signal S 8    1332  at power level P BC2 . Device C  1306  receives and measures signal S 8    1332 , and estimates an expected SINR at communications device B  1304  should concurrent resource usage occur. Device D  1308  receives and measured signal S 3    1322 , and estimates an expected SINR at communications device D  1308  should concurrent resource usage occur. Based on the determined estimated SINRs, device C  1306  and/or device D  1308  make a decision as whether or not a connection  1314  can be established using the same CID as connection  1310 , e.g., both existing and new connection use CID=N 1 . In one embodiment, for the potential connection to be allowed to reuse the resource of interest, both SINRs should be equal to or greater than a threshold limit criteria, e.g., 20 dBs. 
     In some embodiments, control signal S 3    1322  and control signal S 8    1332  are single tone OFDM signals. In some such embodiments, controls signals S 3    1322  and S 8    1332  are conveyed during a connection identifier broadcast interval on specific resources associated with the connection, e.g., on specific OFDM tone-symbol transmission units in a CID broadcast air link resource associated with the existing connection. For example two distinct OFDM tone-symbols in the CID broadcast air link resource are used, one for each signal. 
     Communications device A  1302  also transmits a peer discovery signal S 1    1318  at power level P APD  and a paging signal S 2    1320  at power level P APG . In addition communications device B  1304  transmits a peer discovery signal S 5    1326  at power level P BPD . In various embodiments, at least one of a peer discovery signal and a paging signal is multi-tone signal. In some embodiments, the peer discovery signals (S 1    1318 , S 5    1326 ) and the paging signal (S 2    1320 ) precede the control signals (S 3    1322 , S 8    1332 ). In some embodiments, the transmission power levels of the control signals S 3    1322  and S 8    1332  are based on the power levels of one or more of the peer discovery and/or paging signals ( 1318 ,  1320 ,  1326 ). 
     One exemplary implementation will now be described.
         Pmax=a maximum power level that a device can transmit, e.g., 23 dbm.   h AB =the channel gain from device A to device B, as indicated by dashed line  1311  in  FIG. 13 .   P Thermal =thermal noise power level.   P APD =device A&#39;s peer discovery power.   P APG =device A&#39;s paging power.   P AC1 =device A&#39;s control signal power.   P BPD =device B&#39;s peer discovery power.   P BC2 =device B&#39;s control signal power level.
 
The various quantities at device A are determined as follows.
   1. P APD =Pmax.   2. For defining P APG , let&#39;s define an intermediary entity P A ′ as
 
 P   A   ′*|h   AB | 2 =1000( P   Thermal ).
           P A ′ can be computed through h AB  measured via the peer discovery received power. 1000 represents 30 db over thermal. In some other embodiments, a different gain value is used instead of 1000, e.g., 100.   Then the paging power is defined as
 
 P   APG =min(√( P   A   ′*P max), P max)
   
           3. P AC1 =P APG  
 
The various quantities at device B are determined as follows.
   1. P BPD =Pmax   2. P BC2 =K/(P APG *|h AB | 2 ), where K is a known constant and where P APG *|h AB | 2  can be either (i) measured from the received paging signal of A or (ii) can be inferred directly from a h AB  measurement in peer discovery since P APG  can be inferred from h AB .       

       FIG. 14  is a drawing  1400  illustrating four exemplary wireless communications devices (communications device A  1402 , communications device B  1404 , communications device C  1406 , communications device D  1408 ) and is used to describe features of some embodiments. In the example of  FIG. 14 , device A  1402  and device B  1404  have an existing connection, as indicated by solid line bi-directional arrow  1410 , corresponding to currently held connection identifier  1412 , which is CID=N 1 , e.g., where N 1  is an integer value in the range  1  . . .  168 . In the timing structure being utilized for the example, there is a set of air link resources associated with CID=N 1 . Devices ( 1402 ,  1404 ,  1406 ,  1408 ) are part of a peer to peer communications system in which at least some resources may be, and sometimes are, used concurrently by multiple connections, e.g., depending upon interference conditions. For example, if the first device pair (device A  1402 , device B  1404 ) is far away from second device pair (device C  1406 , device D  1408 ), then the interference levels may be sufficiently low enough that concurrent transmissions may be allowed to occur on the same air link resource. Devices ( 1402 ,  1404 ,  1406 ,  1408 ) are, e.g., peer to peer devices of network  100  of  FIG. 1 . 
     In this example, device C  1406  and device D  1408  would like to have a connection, as indicated by dotted line bi-directional arrow  1414 , and would like to check if they can use the same connection identifier currently held by the device A  1402 /device B  1404  connection, as indicated by block  1416 . In this example, we are concerned about two way communications between device A  1402  and device B  1404  and two way communications between device C  1406  and device D  1408 . When considering a common resource that may be used concurrently by two connections, signals from device A  1402  may cause interference to device D  1408  recovery of signals from device C  1406 , and signals from device D  1408  may cause interference to device A  1402  recovery of signals from device B  1404 . Also, when considering a common resource that may be used concurrently by two connections, signals from device B  1404  may cause interference to device C  1406  recovery of signals from device D  1408 , and signals from device C  1406  may cause interference to device B  1404  recovery of signals from device A  1402 . In addition, signals from device A  1402  may cause interference to device C  1406  recovery of signals from device D  1408 , and signals from device C  1406  may cause interference to device A  1402  recovery of signals from device B  1404 . In addition, signals from device B  1404  may cause interference to device D  1408  recovery of signals from device C  1406 , and signals from device D  1408  may cause interference to device B  1404  recovery of signals from device A  1402 . 
     In accordance with one feature of some embodiments, communications devices of existing connections transmit control signals available for use by potential connection wireless devices to estimate expected SINRs should both the current connection and the potential connection use the same air link resources concurrently. In this example, communications device A  1402  transmits control signal S 3    1422  at power level P AC1  and control signal S 4    1424  at power level P AC2 . Communications device B  1404  transmits control signal S 7    1430  at power level P BC1  and signal S 8    1432  at power level P BC2 . 
     Device C  1406  receives and measures signals S 3    1422 , S 4    1424 , S 7    1430  and S 8    1432  and estimates four SINRs based on its measurements. Similarly, device D  1408  receives and measures signals S 3    1422 , S 4    1424 , S 7    1430  and S 8    1432  and estimates four SINRs based on its measurements. Based on the determined estimated SINRs, device C  1406  and/or device D  1408  make a decision as whether or not a connection  1414  can be established using the same CID as connection  1410 , e.g., both existing and new connection use CID=N 1 . In one embodiment, for the potential connection to be allowed to reuse the resource of interest, each of the eight SINRs should be equal to or greater than a threshold limit criteria, e.g., 20 dBs. 
     In some embodiments, control signal S 3    1422 , control signal S 4    1424 , control signal S 7    1430  control signal S 8    1432  are single tone OFDM signals. In some such embodiments, controls signals S 3    1422 , S 4    1424 , S 7    1430  S 8    1432  are conveyed during a connection identifier broadcast interval on specific resources associated with the connection, e.g., on specific OFDM tone-symbol transmission units in a CID broadcast air link resource associated with the existing connection. For example four distinct OFDM tone-symbols in the CID broadcast air link resource are used, one for each signal. 
     Communications device A  1402  also transmits a peer discovery signal S 1    1418  at power level P APD  and may, and sometimes does, transmit a paging signal S 2    1420  at power level P APG . In addition communications device B  1404  transmits a peer discovery signal S 5    1426  at power level P BPD  and may, and sometimes does, transmit a paging signal S 6    1428  at power level P BPG . In various embodiments, at least one of a peer discovery signal and a paging signal is multi-tone signal. In some embodiments, the peer discovery signals (S 1    1418 , S 5    1426 ) and the paging signal or signals (S 2    1420  and/or S 6    1428 ) precede the control signals (S 3    1422 , S 4    1424 , S 7    1430  S 8    1432 ). In some embodiments, the transmission power levels of the control signals S 3    1422 , S 4    1424 , S 7    1430  and S 8    1432  are based on the power levels of one or more of the peer discovery and/or paging signals ( 1418 ,  1420 ,  1426 ,  1428 ). 
     One exemplary implementation will now be described.
         P max =a maximum power level that a device can transmit, e.g., 23 dbm.   h AB =the channel gain from device A to device B, as indicated by dashed line  1411  in  FIG. 14 .   P Thermal =thermal noise power level.   P APD =device A&#39;s peer discovery power.   P APG =device A&#39;s paging power.   P AC1 =device A&#39;s first control signal power.   P AC2 =device A&#39;s second control signal power.   P BPD =device B&#39;s peer discovery power.   P BPG =device B&#39;s paging power.   P BC1 =device B&#39;s first control signal power.   P BC2 =device B&#39;s second control signal power.
 
The various quantities at device A are determined as follows.
   1. P APD =Pmax   2. For defining P APG , let&#39;s define an intermediary entity P A ′ as
 
 P   A   ′*|hAB| 2=1000( P   Thermal )
           P A ′ can be computed through h AB  measured via the peer discovery received power. 1000 represents 30 db over thermal. In some other embodiments, a different gain value is used, e.g.,  100  instead of 1000. Then the paging power is defined as
 
 P   APG =min(√( P   A   ′*P max), P max)
   
           3. P AC1 =P APG      4. P AC2 =K/(P BPG *|h AB | 2 ), where K is a known constant and where P BPG *|h AB | 2  can be either (i) measured from the received paging signal of B or (ii) can be inferred directly from a h AB  measurement in peer discovery since P BPG  can be inferred from h AB .
 
The various quantities at device B are determined as follows.
   1. P BPD =Pmax   2. For defining P BPG , let&#39;s define an intermediary entity P B ′ as
 
 P   B ′*| h   AB | 2 =1000( P   Thermal )
           P B ′ can be computed through h AB  measured via the peer discovery   
           received power. 1000 represents 30 db over thermal. In some other embodiments, a different gain value is used, e.g., 100 instead of 1000. Then the paging power is defined as
 
 P   BPG =min(√( P   B   ′*P max), P max)
   3. P BC1 =P BPG      4. P BC2 =K/(P APG *|h AB | 2 ), where K is a known constant and where P APG *|h AB | 2  can be either (i) measured from the received paging signal of A or (ii) can be inferred directly from a h AB  measurement in peer discovery since P APG  can be inferred from h AB .       

       FIG. 15  is a flowchart  1500  of an exemplary communications method implemented in a first node in accordance with an exemplary embodiment. The exemplary first node is, e.g., one of communications device A  1302  of  FIG. 13 , communications device B  1304  of  FIG. 13 , communications device A  1402  of  FIG. 14  and communications device B  1404  of  FIG. 14 . The exemplary first node may be one of the peer to peer communications devices of network  100  of  FIG. 1 . Operation of the exemplary method starts in step  1502 , where the first node is powered on and initialized. Operation proceeds from start step  1502  to step  1504 . In step  1504  the first node establishes a communications connection with a second node. Operation proceeds from step  1504  to step  1506 . 
     In step  1506  the first node receives a first signal from the second node. In some embodiments, the first signal is one of a peer discovery signal or a paging signal. Operation proceeds from step  1506  to step  1508 . In step  1508  the first node determines a first power level of the received first signal. In some embodiments, the first signal is transmitted on multiple tone-symbols, said first power level being an average per tone-symbol power level. In various embodiments, a tone-symbol is a time-frequency airlink resource unit of one tone for one symbol transmission time interval. In some embodiments, the multiple tone-symbols on which the first signal is transmitted include tone-symbols corresponding to different symbol transmission time periods. 
     In some embodiments, e.g., a uni-directional resource reuse case, operation proceeds from step  1508  to step  1512 . In other embodiments, e.g., a bi-directional resource reuse case, operation proceeds from step  1508  to step  1510 . In step  1510  the first node transmits a third signal at a third power level. In some embodiments, the third power level is a power level having a predetermined relationship to the first power level. In some embodiments, the third signal is a single tone signal, e.g., a single tone OFDM signal communicated on one OFDM tone-symbol. Operation proceeds from step  1510  to step  1512 . 
     In step  1512  the first node transmits a second signal at a second power level which has a predetermined relationship to the determined first power level. In some embodiments, the predetermined relationship is that the second power level is inversely proportional to the first power level. The second signal, in some embodiments, is a single tone signal, e.g., a single tone OFDM signal communicated on one OFDM tone-symbol. Operation proceeds from step  1512  to step  1514 . In step  1514  the first node determines if the established connections still exists. If the established communications connection still exists, then operation proceeds from step  1514  to step  1506 . In step  1506  the first node receives another first signal from the second node. However, if the established connection no longer exists, operation proceeds from step  1514  to stop step  1516 . 
     As one example, consider that the first node is communications device B  1304  of  FIG. 13  and the second node is communications device A  1302  of  FIG. 13 , then the first signal is received peer discovery signal S 1    1318  or received paging signal S 2    1320 , and the second signal is control signal S 8    1332 . As another example, consider that the first node is communications device B  1404  of  FIG. 14  and the second node is communications device A  1402  of  FIG. 14 , then the first signal is received peer discovery signal S 1    1418  or received paging signal S 2    1420 , the second signal is control signal S 8    1432 , and the third signal is control signal S 7    1430 . 
     As another example, consider that the first node is communications device A  1302  and the second node is communications device B  1304 , then the first signal is received peer discovery signal S 5    1326 , and the second signal is control signal S 3    1322 . As still another example, consider that the first node is communications device A  1402  and the second node is communications device B  1404 , then the first signal is received peer discovery signal S 5    1426  or received paging signal S 6   1428 , the second signal is control signal S 4    1424 , and the third signal is control signal S 3    1422 . 
     In some embodiments, the control signals (S 3 , S 4 , S 7 , S 8 ) are useful for interference management and/or resource scheduling purposes, e.g., particularly useful in a peer to peer network implementing decentralized scheduling and/or managed air link resource re-usage. For example, the second and third signals transmitted by the first node implementing the method of flowchart  1500  of  FIG. 15  may be, and sometimes are, used by other nodes seeking to establish a connection and evaluate whether a resource in use by the existing communications connection can be reused concurrently by a new connection. 
     In  FIGS. 13 and 14 , resource reuage has been described in the context of a connection identifier with associated air link resources. In general the methods and apparatus of various embodiments are also applicable to other resources, e.g., a traffic segment under contention. 
       FIG. 16  is a drawing of an exemplary communications device  1600  in accordance with an exemplary embodiment. Exemplary communications device  1600  is, e.g., one of communications device A  1302  of  FIG. 13 , communications device B  1304  of  FIG. 13 , communications device A  1402  of  FIG. 14 , and communications device B  1404  of  FIG. 14 . Communications device  1600  may be one of the exemplary peer to peer communications devices of network  100  of  FIG. 1 . Exemplary communications device  1600  implements a method in accordance with flowchart  1500  of  FIG. 15 . 
     Communications device  1600  includes a processor  1602  and memory  1604  coupled together via a bus  1609  over which the various elements ( 1602 ,  1604 ) may interchange data and information. Communications device  1600  further includes an input module  1606  and an output module  1608  which may be coupled to processor  1602  as shown. However, in some embodiments, the input module  1606  and output module  1608  are located internal to the processor  1602 . Input module  1606  can receive input signals. Input module  1606  can, and in some embodiments does, include a wireless receiver and/or a wired or optical input interface for receiving input. Output module  1608  may include, and in some embodiments does include, a wireless transmitter and/or a wired or optical output interface for transmitting output. 
     Processor  1602  is configured to: receive a first signal from a second node; determine a first power level of the received first signal; and transmit a second signal at a second power level which has a predetermined relationship to the determined first power level. In some embodiments, said predetermined relationship is that said second power level is inversely proportional to the determined first power level. 
     The first signal is, in some embodiments, one of a peer discovery signal or a paging signal. In some embodiments, the first signal is transmitted on multiple tone-symbols, said first power level being an average per tone-symbol power level. In some such embodiments, said multiple tone-symbols include tone-symbols corresponding to different symbol transmission time periods. 
     The second signal, in various embodiments, is a single tone signal, e.g., a single tone OFDM signal communicated on a single OFDM tone-symbol. In some embodiments the single OFDM tone-symbol is part of a connection identifier broadcast block. 
     In some embodiments, processor  1602  is further configured to: establish a communications connection with said second node prior to transmitting said second signal. In various embodiments, processor  1602  is further configured to: transmit a third signal at a third power level. The third power level is, in some embodiments, a power level having a predetermined relationship to the first power level. 
       FIG. 17  is an assembly of modules  1700  which can be, and in some embodiments are, used in the communications device  1600  illustrated in  FIG. 16 . The modules in the assembly  1700  can be implemented in hardware within the processor  1602  of  FIG. 16 , e.g., as individual circuits. Alternatively, the modules may be implemented in software and stored in the memory  1604  of the communications device  1600  shown in  FIG. 16 . While shown in the  FIG. 16  embodiment as a single processor, e.g., computer, it should be appreciated that the processor  1602  may be implemented as one or more processors, e.g., computers. When implemented in software the modules include code, which when executed by the processor, configure the processor, e.g., computer,  1602  to implement the function corresponding to the module. In embodiments where the assembly of modules  1700  is stored in the memory  1604 , the memory  1604  is a computer program product comprising a computer readable medium comprising code, e.g., individual code for each module, for causing at least one computer, e.g., processor  1602 , to implement the functions to which the modules correspond. 
     Completely hardware based or completely software based modules may be used. However, it should be appreciated that any combination of software and hardware (e.g., circuit implemented) modules may be used to implement the functions. As should be appreciated, the modules illustrated in  FIG. 17  control and/or configure the communications device  1600  or elements therein such as the processor  1602 , to perform the functions of the corresponding steps illustrated in the method flowchart  1500  of  FIG. 15 . 
     Assembly of modules  1700  includes: a module  1704  for establishing a communications connection with a second device prior to transmitting the second signal, a module  1706  for receiving a first signal from a second node, a module  1708  for determining a first power level of the received first signal, a module  1712  for transmitting a second signal at a second power level which has a predetermined relationship to the first power level, and a module  1714  for determining if the established connection still exists. In some embodiments, e.g., an embodiment supporting bi-directional resource reuse, assembly of modules  1700  further includes a module  1710  for transmitting a third signal at a third power level. In various embodiments, the third power level is a power level having a predetermined relationship to the first power level. 
     In some embodiments the predetermined relationship relating the second power level to the first power level is that the second power level is inversely proportional to the determined first power level. In some embodiments, the first power level is one of a peer discovery signal or a paging signal. In some such embodiments, the first signal is transmitted on multiple tone-symbols and the first power level is an average per tone-symbol power level. In some such embodiments, the multiple tone-symbols include tone-symbols corresponding to different symbol transmission time periods. 
     The second signal, in some embodiments, is a single tone signal, e.g., a single tone OFDM signal communicated on a single OFDM tone-symbol. The third signal in some embodiments, is a single tone signal, e.g., a single tone OFDM signal communicated on a single OFDM tone-symbol. In some embodiments, the second and third signals are communicated on different OFDM tone-symbols in a connection identifier transmission block, e.g., two different OFDM tone-symbols which map to the current connection of node  1600 . 
     The techniques of various embodiments may be implemented using software, hardware and/or a combination of software and hardware. Various embodiments are directed to apparatus, e.g., relay stations, mobile nodes such as mobile access terminals, base stations including one or more attachment points, and/or communications systems. Various embodiments are also directed to methods, e.g., method of controlling and/or operating relay stations, mobile nodes, base stations and/or communications systems, e.g., hosts. Various embodiments are also directed to machine, e.g., computer, readable medium, e.g., ROM, RAM, CDs, hard discs, etc., which include machine readable instructions for controlling a machine to implement one or more steps of a method. 
     It is understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented. 
     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, receiving a signal, determining a received power level power, estimating an SINR, making a resource reuse decision, determining a control signal transmission power level, and/or transmitting a control signal, etc. Thus, 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). Some embodiments are directed to a device, e.g., communications device, including a processor configured to implement one, multiple or all of the steps of one or more methods of the invention. 
     Some embodiments are directed to a computer program product comprising a computer-readable medium comprising code for causing a computer, or multiple computers, to implement various functions, steps, acts and/or operations, e.g. one or more steps described above. Depending on the embodiment, the computer program product can, and sometimes does, include different code for each step to be performed. Thus, the computer program product may, and sometimes does, include code for each individual step of a method, e.g., a method of controlling a communications device or node. The code may be in the form of machine, e.g., computer, executable instructions stored on a computer-readable medium such as a RAM (Random Access Memory), ROM (Read Only Memory) or other type of storage device. In addition to being directed to a computer program product, some embodiments are directed to a processor configured to implement one or more of the various functions, steps, acts and/or operations of one or more methods described above. Accordingly, some embodiments are directed to a processor, e.g., CPU, configured to implement some or all of the steps of the methods described herein. The processor may be for use in, e.g., a communications device or other device described in the present application. 
     In some embodiments, the processor or processors, e.g., CPUs, of one or more devices, e.g., communications devices such as wireless terminals which may be mobile devices, base stations, and/or relay stations are configured to perform the steps of the methods described as being performed by the communications device. Accordingly, some but not all embodiments are directed to a device, e.g., communications device, with a processor which includes a module corresponding to each of the steps of the various described methods performed by the device in which the processor is included. In some but not all embodiments a device, e.g., communications device, includes a module corresponding to each of the steps of the various described methods performed by the device in which the processor is included. The modules may be implemented using software and/or hardware. 
     While described in the context of an OFDM system, at least some of the methods and apparatus of various embodiments are applicable to a wide range of communications systems including many non-OFDM and/or non-cellular systems. At least some of the methods and apparatus are applicable to hybrid systems, e.g. a system including OFDM and CDMA signaling techniques. 
     Numerous additional variations on the methods and apparatus of the various embodiments described above will be apparent to those skilled in the art in view of the above description. Such variations are to be considered within the scope. The methods and apparatus 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 mobile nodes, between mobile nodes and relay stations, between access nodes and mobile nodes, between access nodes and relay station, and/or between relay stations and mobile nodes. In some embodiments the access nodes are implemented as base stations which establish communications links with mobile nodes and/or relay stations 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.