Abstract:
Methods and apparatus related to peer/network/service discovery in a mobile wireless system, e.g., an ad hoc peer-to-peer network are described. Transmission of discovery information, e.g., upper layer discovery information, is divided into a number of portions to be transmitted separately over time. Transmission of the individual portions is structured so as to enable flexibility in the frequency of the peer discovery transmissions as well as the monitoring of such transmissions. Various embodiments facilitate rapid discovery and/or secure discovery, e.g., selective discovery by trusted peers.

Description:
FIELD 
     Various embodiments relate to wireless communications, and more particularly, to methods and apparatus related to the communication of peer discovery information. 
     BACKGROUND 
     In a wireless network, e.g., an ad hoc peer to peer wireless network, it can be beneficial for a wireless communications device, e.g., a mobile node, to support the ability to transmit, e.g., broadcast, various types of discovery information, e.g., peer discovery information, network discovery information and/or service discovery information. The broadcasting of such information can be used by other peer devices currently in its local vicinity to form a situational awareness. This exchange of wireless device broadcast discovery information among peers can be particularly useful in a network lacking centralized coordination and/or control. Different wireless communications devices may have different capabilities and/or needs with regard to the transmission and/or reception of discovery information. In addition, an individual wireless communications device may, at different times, have different capabilities and/or needs with regard to the transmission and/or reception of discovery information. Broadcasting and/or receiving discovery information may be considered overhead signaling, and resources such as power and spectrum over time expended for discovery information signaling may be unavailable for traffic signaling. The power expended by a mobile wireless communications device for transmitting and/or receiving discovery information and the reserve battery power remaining are important considerations in implementing a structure supporting the communication of discovery information. 
     Based on the above discussion it should be appreciated that there is a need for methods and/or apparatus that support the communication of a wide range of different types of discovery information in an efficient manner and that methods and apparatus that allow for flexibility in the transmission and/or reception of discovery information would be beneficial. 
     SUMMARY 
     Methods and apparatus related to peer/network/service discovery in a mobile wireless system, e.g., an ad hoc peer-to-peer network are described. Transmission of discovery information, e.g., upper layer discovery information, is divided into a number of portions to be transmitted separately over time. Transmission of the individual portions is structured so as to enable flexibility in the frequency of the peer discovery transmissions as well as the monitoring of such transmissions. Various embodiments facilitate rapid discovery and/or secure discovery, e.g., selective discovery by trusted peers. 
     An exemplary method of communicating discovery information, in accordance with some embodiments, comprises: storing information defining a peer discovery transmission structure, said structure indicting a plurality of ordered transmission units available for transmitting peer discovery information. The stored information includes information indicating transmission units to be used for low rate discovery transmissions and additional transmission units to be used for high rate discovery transmissions. In one but not necessarily all embodiments the stored information indicates that more transmission units for high rate discovery transmissions than for low rate discovery transmissions. However, different relationships between the number of high and low rate transmission units are also possible. The exemplary method further comprises transmitting a first portion of a set of peer discovery information using a transmission unit corresponding to said low rate discovery transmissions; and transmitting a previously transmitted portion of a set of peer discovery information using a transmission unit corresponding to said high rate discovery transmissions. 
     An exemplary wireless communications device for communicating discovery information, in accordance with some embodiments, comprises: memory including stored information defining a peer discovery transmission structure, said structure indicting a plurality of ordered transmission units available for transmitting peer discovery information. The stored information includes information indicating transmission units to be used for low rate discovery transmissions and additional transmission units to be used for high rate discovery transmissions. In one particular exemplary embodiment the stored information indicates more transmission units for high rate discovery transmissions than for low rate discovery transmissions but this is only exemplary and not necessarily required for all embodiments. The exemplary wireless communications device further comprises: a wireless transmitter module for transmitting portions of peer discovery information and a low rate control module for controlling said wireless transmitter module to transmit a first portion of a set of peer discovery information using a transmission unit corresponding to said low rate discovery transmissions. In various embodiments, the wireless communications device further comprises: a high rate control module for controlling said wireless transmitter module to transmit a previously transmitted portion of a set of peer discovery information using a transmission unit corresponding to said high rate discovery transmissions. 
     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 peer to peer network in accordance with an exemplary embodiment. 
         FIG. 2  illustrates discovery intervals and corresponding discovery interval air link resources within a recurring peer to peer timing structure in accordance with an exemplary embodiment. 
         FIG. 3  illustrates a more detailed representation of a first exemplary discovery interval&#39;s air link resources. 
         FIG. 4  illustrates a more detailed representation of a second exemplary discovery interval&#39;s air link resources. 
         FIG. 5  illustrates a plurality of ordered transmission units available for transmitting discovery information corresponding to a device identifier which are part of a peer discovery transmission structure. 
         FIG. 6  illustrates a securing hash function encoding module processing input discovery information to generate encoded information. 
         FIG. 7  illustrates a securing hash function encoding module processing some input discovery information, e.g., discovery identification information, which generates secure encoded information. 
         FIG. 8  illustrates 3 exemplary formats for discovery information being conveyed using four output portions corresponding to input discovery information. 
         FIG. 9  illustrates mapping of generated portions to ordered transmission units for conveying discovery information associated with a device identifier in accordance with one exemplary embodiment. 
         FIG. 10  illustrates mapping of generated portions to ordered transmission units for conveying discovery information associated with a device identifier in accordance with another exemplary embodiment. 
         FIG. 11  is a flowchart of an exemplary method of operating a communications device, e.g., a wireless terminal, to communicate discovery information. 
         FIG. 12 , comprising the combination of  FIG. 12A  and  FIG. 12B , is a flowchart of an exemplary method of operating a wireless terminal, e.g., a mobile node supporting peer to peer communications, to communicate discovery information, in accordance with an exemplary embodiment. 
         FIG. 13  is a drawing of an exemplary wireless terminal, e.g., peer to peer mobile node, which transmits discovery information portions in accordance with an exemplary embodiment. 
         FIG. 14  is a drawing illustrating exemplary nodes in a peer to peer communications system and the transmission of discovery information at different rates. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a drawing of an exemplary peer to peer network  100  in accordance with an exemplary embodiment. 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 ). Some of the peer to peer communications devices, e.g., peer to peer communications device  4   108 , also include a wired interface which couples the device to other nodes and/or the Internet. The peer to peer communications devices ( 102 ,  104 ,  106 ,  108 ,  110 ) store information defining a peer discovery transmission structure including transmission units to be used for low rate discovery transmissions and additional transmission units to be used for high rate discovery transmissions. 
     Peer to peer network  100  also includes a peer discovery assist node  114 , a server node  112 , e.g., a base station, and a beacon transmitter  116 . Peer discovery assist node  114  can, and sometimes does, receives portions of one or more sets of peer discovery information from one or more peer to peer communications devices at a first rate and transmits the information over an airlink at a second rate which is faster than the first rate. Similarly, server node  112  can, and sometimes does, receives portions of one or more sets of peer discovery information from a peer to peer communications device at a first rate and transmits the information over an airlink at a second rate which is faster than the first rate. Server node  112  includes both a wireless interface and a wired interface. The wired interface of the server  112  couples the server to other network nodes and/or the Internet. Beacon transmitter  116  transmits a beacon signal, e.g., an OFDM beacon signal having a high power concentration on one or a few tones, which is easily detectable and intended to be utilized by the peer to peer devices in its vicinity to establish a timing reference with respect to the peer to peer timing structure being utilized in the region. 
       FIG. 2  includes a drawing  200  illustrating discovery intervals (discovery interval  1   214 , discovery interval  2   216 , . . . , discovery interval n  218 ) within a recurring peer to peer timing structure including an ultra slot  212 . In the recurring peer to peer timing structure the ultra slot repeats. Vertical axis  202  represents frequency, e.g., OFDM tones, while horizontal axis  204  represents time. Corresponding to each of discovery intervals (discovery interval  1   214 , discovery interval  2   216 , . . . , discovery interval n  218 ) there is a corresponding block of discovery interval air link resources (discovery interval  1  air link resources  206 , discovery interval  2  air link resources  208 , . . . , discovery interval n air link resources  210 ). Each block of discovery interval air link resources, e.g., discovery interval  1  air link resources  206 , is, e.g., a block of OFDM tone-symbols, where each OFDM tone-symbol represents one OFDM tone for the duration of one OFDM symbol transmission time interval. 
       FIG. 3  shows a more detailed representation of discovery interval  1  air link resources  206  in accordance with one exemplary embodiment. Discovery interval  1  air link resources  206  include a plurality of discovery air link resources corresponding to different device identifiers. Discovery interval  1  air link resources includes device ID  1  discovery resource  302 , followed by device ID  2  discovery resource  304 , followed by device ID  3  discovery resource  306 , followed by device ID  4  discovery resource  308 , followed by device ID  5  discovery resource  310 , followed by device ID  6  discovery resource  312 , followed by device ID  7  discovery resource  314 , . . . , and device ID M discovery resource  316 . 
       FIG. 4  shows a more detailed representation of discovery interval  2  air link resources  208  in accordance with one exemplary embodiment. Discovery interval  2  air link resources  208  include a plurality of discovery air link resources corresponding to different device identifiers. Discovery interval  2  air link resources  208  includes device ID  3  discovery resource  402 , followed by device ID  5  discovery resource  404 , followed by device ID  4  discovery resource  406 , followed by device ID M discovery resource  408 , followed by device ID  2  discovery resource  410 , followed by device ID  6  discovery resource  412 , followed by device ID  1  discovery resource  414 , . . . , and device ID  7  discovery resource  416 . It may be observed that the order of the discovery resources associated with different device identifiers has changed from discovery interval  1   206  to discovery interval  2   208  in this exemplary embodiment. The ordered change in accordance with a predetermined hopping sequence employed in the peer to peer timing/frequency structure being utilized. In some other embodiments, the relative position of air link resources associated with a particular device identifier does not change from one interval to the next. 
       FIG. 5  is a drawing  500  illustrating a plurality of ordered transmission units available for transmitting discovery information which are part of a peer discovery transmission structure. The plurality of illustrated ordered transmission units include transmission unit  0   502 , transmission unit  1   504 , transmission unit  2   506 , transmission unit  3   508 , transmission unit  4   510 , transmission unit  5   512 , transmission unit  6   514 , transmission unit  7   516 , transmission unit  8   518 , transmission unit  9   520 , transmission unit  10   522 , transmission unit  11   524 , transmission unit  12   526 , transmission unit  13   528 , transmission unit  14   530 , transmission unit  15   532 , transmission unit  16   534 , transmission unit  17   536 , transmission unit  18   538  and transmission unit  19   540 , which are part of a peer discovery transmission structure, and which are associated with a particular device identifier. For example, consider that the transmission units in drawing  500  of  FIG. 5  belong to device ID  2 . Continuing with the example, transmission unit  0   502  may be device ID  2  discovery resource  304  of discovery interval  1  air link resources  206  and transmission unit  1   504  may be device ID  2  discovery resource  410  of discovery interval  2  of air link resources  208 , as illustrated in  FIGS. 2 ,  3  and  4 . 
     The plurality of ordered transmission units available for transmitting peer discovery information includes low rate discovery transmission units corresponding to a device identifier as indicated by grouping  542  and additional transmission units to be used for high rate discovery corresponding to the same device identifier as indicated by grouping  544 . In this example, the set of low rate discovery transmission units corresponding to the device identifier  542  are illustrated with crosshatch shading and include transmission units  502 ,  512 ,  522  and  532 . The set of additional transmission units to be used for high rate discovery corresponding to the device identifier are illustrated without shading and include transmission units  504 ,  506 ,  508 ,  510 ,  514 ,  516 ,  518 ,  520 ,  524 ,  526 ,  528 ,  530 ,  534 ,  536 ,  538  and  540 . 
       FIG. 6  illustrates a securing hash function encoding module  604  processing input discovery information which generates encoded information. The output encoded information is mapped to portions, each portion being communicated via a transmission unit. 
     Drawing  600  illustrates that the secure hash function encoding module  604  receives discovery information  602  and time value t 0   606  and generates a set of output information including a plurality of portions (A N-2 , B N-2 , C N-2 , D N-2 ) as indicated by column  608 . In this example, each portion corresponds to 16 information bits as indicated by column  610 . Column  612  indicates that there is a correspondence between different encoded output portions and transmission unit types. More particularly, portion A N-2  is to be communicated using a P 0  transmission unit type in the recurring timing structure; portion B N-2  is to be communicated using a P 1  transmission unit type in the recurring timing structure; portion C N-2 , is to be communicated using a P 2  transmission unit type in the recurring timing structure; and portion D N-2 , is to be communicated using a P 3  transmission unit type in the recurring timing structure. 
     Drawing  630  illustrates that the secure hash function encoding module  604  receives discovery information  632  and time value t 1   636  and generates a set of output information including a plurality of portions (A N-1 , B N-1 , C N-1 , D N-1 ) as indicated by column  638 . In this example, each portion corresponds to 16 information bits as indicated by column  640 . Column  642  indicates that there is a correspondence between different encoded output portions and transmission unit types. More particularly, portion A N-1  is to be communicated using a P 0  transmission unit type in the recurring timing structure; portion B N-1  is to be communicated using a P 1  transmission unit type in the recurring timing structure; portion C N-1 , is to be communicated using a P 2  transmission unit type in the recurring timing structure; and portion D N-1 , is to be communicated using a P 3  transmission unit type in the recurring timing structure. 
     Drawing  650  illustrates that the secure hash function encoding module  604  receives discovery information  652  and time value t 2   656  and generates a set of output information including a plurality of portions (A N , B N , C N , D N ) as indicated by column  658 . In this example, each portion corresponds to 16 information bits as indicated by column  660 . Column  662  indicates that there is a correspondence between different encoded output portions and transmission unit types. More particularly, portion A N  is to be communicated using a P 0  transmission unit type in the recurring timing structure; portion B N  is to be communicated using a P 1  transmission unit type in the recurring timing structure; portion C N , is to be communicated using a P 2  transmission unit type in the recurring timing structure; and portion D N  is to be communicated using a P 3  transmission unit type in the recurring timing structure. 
     Input discovery information  602  may be the same or different from input discovery information  632 . Similarly, input discovery information  632  may be the same or different from input discovery information  652 . In each case, the secure hashing function encoding module  604  may, and in some instances does, include additional inputs, e.g., a key, as needed for operation. 
       FIG. 7  illustrates a securing hash function encoding module  704  processing some input discovery information, e.g. discovery identification information, which generates secure encoded information. The output secure encoded information is combined by combining module  703  with additional discovery information, e.g., bits representing type information and/or flags. The result of the combination is mapped to portions, each portion being communicated via a transmission unit. 
       FIG. 7  thus illustrates a variation on the exemplary embodiment shown in  FIG. 6 . In the example of  FIG. 7  some discovery information which is communicated is not subjected to secure hash function encoding. For example, bits representing type information and/or bits representing flags may be, and sometimes are, not subjected to secure hash function encoding. In the example of  FIG. 7 , discovery information ( 702 ,  732 ,  752 ) includes discovery information ( 702   a ,  732   a ,  752   a ), respectively, which is subjected to secure hash function encoding and discovery information ( 702   b ,  732   b ,  752   b ), respectively, which is not subjected to secure hash function encoding. 
     Drawing  700  illustrates that the secure hash function encoding module  704  receives discovery information  702   a  and time value t 0   706  and generates secure encoded information  705 . Combining module  703  receives secure encoded information  705  and discovery information  702   b  and generates a set of output information including a plurality of portions (A N-2 , B N-2 , C N-2 , D N-2 ) as indicated by column  708 . In this example, each portion corresponds to 20 information bits as indicated by column  710 . Column  712  indicates that there is a correspondence between different encoded output portions and transmission unit types. More particularly, portion A N-2  is to be communicated using a P 0  transmission unit type in the recurring timing structure; portion B N-2  is to be communicated using a P 1  transmission unit type in the recurring timing structure; portion C N-2 , is to be communicated using a P 2  transmission unit type in the recurring timing structure; and portion D N-2 , is to be communicated using a P 3  transmission unit type in the recurring timing structure. 
     Drawing  730  illustrates that the secure hash function encoding module  704  receives discovery information  732   a  and time value t 1   736  and generates secure encoded information  735 . Combining module  703  receives secure encoded information  735  and discovery information  732   b  and generates a set of output information including a plurality of portions (A N-1 , B N-1 , C N-1 , D N-1 ) as indicated by column  738 . In this example, each portion corresponds to 20 information bits as indicated by column  740 . Column  742  indicates that there is a correspondence between different encoded output portions and transmission unit types. More particularly, portion A N-1  is to be communicated using a P 0  transmission unit type in the recurring timing structure; portion B N-1  is to be communicated using a P 1  transmission unit type in the recurring timing structure; portion C N-1 , is to be communicated using a P 2  transmission unit type in the recurring timing structure; and portion D N-1 , is to be communicated using a P 3  transmission unit type in the recurring timing structure. 
     Drawing  750  illustrates that the secure hash function encoding module  704  receives discovery information  752   a  and time value t 2   756  and generates secure encoded information  755 . Combining module  703  receives secure encoded information  755  and discovery information  752   b  and generates a set of output information including a plurality of portions (A N , B N , C N , D N ) as indicated by column  758 . In this example, each portion corresponds to 20 information bits as indicated by column  760 . Column  762  indicates that there is a correspondence between different encoded output portions and transmission unit types. More particularly, portion A N  is to be communicated using a P 0  transmission unit type in the recurring timing structure; portion B N  is to be communicated using a P 1  transmission unit type in the recurring timing structure; portion C N , is to be communicated using a P 2  transmission unit type in the recurring timing structure; and portion D N , is to be communicated using a P 3  transmission unit type in the recurring timing structure. 
     Input discovery information  702  may be the same or different from input discovery information  732 . Similarly, input discovery information  732  may be the same or different from input discovery information  752 . In each case, the secure hashing function encoding module  604  may, and in some instances does, include additional inputs, e.g., a key, as needed for operation. 
       FIG. 8  illustrates 3 exemplary formats for discovery information being conveyed using four output portions. Drawing  800  illustrates a first exemplary format in which output discovery identification information  802  to be transmitted includes 64 bits as indicated by block  804  and includes 4 portions (portion A  806 , portion B  808 , portion C  810 , and portion D  812 . This format is an exemplary format corresponding to the examples of  FIG. 6 . For example, the four output portions (portion A  806 , portion B  808 , portion C  810 , portion D  812 ) of drawing  800  of  FIG. 8  are the set of {A n-2 , B n-2 , C n-2  and D n-2 }, or the set of four output portions are {A n-1 , B n-1 , C n-1  and D n-1 }, or the set {A n , B n , C n  and D n } of  FIG. 6 . 
     Drawing  820  illustrates a second exemplary format in which output discovery identification information  834  to be transmitted includes 80 bits and includes 4 output portions (portion A  834 , portion B  836 , portion C  838 , and portion D  840 ). This format is an exemplary format corresponding to the examples of  FIG. 7 . For example, the four output portions (portion A  834 , portion B  836 , portion C  838 , portion D  840 ) of drawing  820  of  FIG. 8  are the set of {A n-2 , B n-2 , C n-2  and D n-2 }, or the set of four output portions are {A n-1 , B n-1 , C n-1  and D n-1 }, or the set {A n , B n , C n  and D n } of  FIG. 7 . In example of drawing  820 , the output discovery information to be communicated includes a type field  822  which is 8 bits wide as indicated by  828  and a flags field  824  which is 8 bits wide as indicated by block  830  and a discovery identification information field  826  which is 64 bits wide as indicated by block  832 . In the example of drawing  820  the type field  822  and the flags field  824  are included as part of portion A  834 , while the discovery identification information  826  is communicated using bits in portion A  834 , portion B  836 , portion C  838  and portion D  840 . 
     Drawing  850  illustrates a third exemplary format in which output discovery identification information  834  to be transmitted includes 80 bits and includes 4 output portions (portion A  893 , portion B  895 , portion C  897 , and portion D  899 ). This format is an exemplary format corresponding to the examples of  FIG. 7 . For example, the four output portions (portion A  893 , portion B  895 , portion C  897 , portion D  899 ) of drawing  850  of  FIG. 8  are the set of {A n-2 , B n-2 , C n-2  and D n-2 }, or the set of four output portions are {A n-1 , B n-1 , C n-1  and D n-1 }, or the set {A n , B n , C n  and D n } of  FIG. 7 . In the example of drawing  850 , the discovery information to be communicated in portion A  893  includes a type field  852  which is 2 bits wide as indicated by block  876 , a flags field  854  which is 2 bits wide as indicated by block  878  and a discovery identification information field  856  which is 16 bits wide as indicated by block  880 . The discovery information to be communicated in portion B  895  includes a type field  858  which is 2 bits wide as indicated by block  882 , a flags field  860  which is 2 bits wide as indicated by block  884  and a discovery identification information field  862  which is 16 bits wide as indicated by block  886 . The discovery information to be communicated in portion C  897  includes a type field  864  which is 2 bits wide as indicated by block  888 , a flags field  866  which is 2 bits wide as indicated by block  890  and a discovery identification information field  868  which is 16 bits wide as indicated by block  892 . The discovery information to be communicated in portion D  899  includes a type field  870  which is 2 bits wide as indicated by  894 , a flags field  872  which is 2 bits wide as indicated by block  896  and a discovery identification information field  874  which is 16 bits wide as indicated by block  898 . 
     Type information conveyed in a type field includes, e.g., information indicating a format of other discovery information being conveyed, e.g., other upper layer discovery information. For example, a type value conveyed in the type field is used to identify how to process the discovery information being conveyed, e.g., different type values map to different formats which can be used and/or different encoding which can be used and/or different encryptions which can be used. Type field information can be, and sometimes is, used to convey what the contents of processed, e.g., hashed, discovery information represents. 
     Flags are used to indicate one or more binary conditions, e.g., capabilities or features. In some embodiments, flags are used to identify a device type, e.g., a router. In some embodiments, a portion of the discovery information to be conveyed is included in every transmission portion. In some embodiments, a portion of the discovery information to be conveyed is split over a set of associated peer discovery transmission portions. Some portions of discovery information, e.g. a subset of flags may be sufficiently time critical to include in every transmission portion. In some embodiments, to be able to interpret some discovery information being communicated, a receiving device needs to have already received a type value; thus in such an embodiment, the frequency at which Type is conveyed can, and sometimes does, impact the ability to react to partial sets of discovery information. In some such embodiments, a type field is included in each discovery transmission portion to facilitate rapid recovery of discovery information being conveyed in a received transmitted portion. 
     Other embodiments, may include other fields in addition to or in place of those described with respect to  FIG. 8 , e.g., a header field, a CRC field, etc. 
       FIG. 9  illustrates mapping of the generated portions of  FIG. 6  or  FIG. 7  to ordered transmission units for conveying discovery information associated with a wireless communications device identifier in accordance with one exemplary embodiment using a particular mapping pattern. An ordered sequence of transmission units ( 904 ,  906 ,  908 ,  910 ,  912 ,  914 ,  916 ,  918 ,  920 ,  922 ,  924 ,  926 ,  928 ,  930 ,  932 ,  934 ,  936 ,  938 ,  940 ,  942 ,  944 ,  946 ,  948 ,  950 ,  952 ,  954 ,  956 ,  958 ,  960 ,  962 ,  964 ,  966 ,  968 ,  970 ,  972 ,  974 ,  976 ,  978 ,  980 ,  982 ) which are of the type (P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 ), respectively, and which convey information (A N-1 , B N-2 , C N-2 , D N-2 , A N-1 , B N-1 , C N-2 , D N-2 , A N-1 , B N-1 , C N-1 , D N-2 , A N-1 , B N-1 , C N-1 , D N-1 , A N-1 , B N-2 , C N-1 , D N-1 , A N , B N-1 , C N-1 , D N-1 , A N , B N , C N-1 , D N-1 , A N , B N , C N , D N-1 , A N , B N , C N , D N , A N , B N , C N , D N ), respectively. It may be observed that transmission units ( 904 ,  914 ,  924 ,  934 ,  944 ,  954 ,  964 , and  974 ) are low rate discovery transmission units as indicated by crosshatch shading, while transmission units ( 906 ,  908 ,  910 ,  912 ,  916 ,  918 ,  920 ,  922 ,  926 ,  928 ,  930 ,  932 ,  936 ,  938 ,  940 ,  942 ,  946 ,  948 ,  950 ,  952 ,  956 ,  958 ,  960 ,  962 ,  966 ,  968 ,  970 ,  972 ,  976 ,  978 ,  980  and  982 ) are additional transmission units to be used for high rate discovery. It should be noted, that an additional transmission unit for high rate discovery of a given type is designated to carry the information portion that has been previously transmitted via a low rate discovery transmission unit of the same type, when it carries a transmission unit. 
     If a first peer to peer communications device having the identifier corresponding to the set of transmission units is in high rate discovery information transmit mode, it transmits using each of the transmission units. However, if first the peer to peer communications device is in low rate discovery transmit mode it transmits using the low rate discovery resources, but refrains from transmitting on the additional transmission resources designated for high rate discovery. The structure of  FIG. 9  illustrates the dissemination of the same portions of discovery information from a first peer to peer communications irrespective of the transmit mode, but facilitates a more rapid potential recovery of the information by a second peer to peer device if high rate mode is used. In addition, this illustrated structure of  FIG. 9  advantageously facilitates a peer discovery assist node or base station being able to: (i) receive and detect discovery signals being communicated from a first peer to peer communications device transmitting discovery signals using low discovery rate transmission units but not additional transmission units designated for high discovery rate, and (ii) then broadcast such received information using the additional transmission units designated for high rate discovery, e.g., filling in the otherwise unused additional transmission units designated for high rate discovery. A second peer to peer communications device attempting to detect peer discovery information from the first peer discovery device can receive and process discovery transmission units which occur on each of the transmission units associated with the device identifier. The second peer to peer communications device need not know the transmission source of a particular additional transmission unit signal, e.g., the first communications device or the assist node. 
       FIG. 10  illustrates mapping of the generated portions of  FIG. 6  or  FIG. 7  to ordered transmission units for conveying discovery information associated with a wireless communications device identifier in accordance with another exemplary embodiment. An ordered sequence of transmission units ( 1004 ,  1006 ,  1008 ,  1010 ,  1012 ,  1014 ,  1016 ,  1018 ,  1020 ,  1022 ,  1024 ,  1026 ,  1028 ,  1030 ,  1032 ,  1034 ,  1036 ,  1038 ,  1040 ,  1042 ,  1044 ,  1046 ,  1048 ,  1050 ,  1052 ,  1054 ,  1056 ,  1058 ,  1060 ,  1062 ,  1064 ,  1066 ,  1068 ,  1070 ,  1072 ,  1074 ,  1076 ,  1078 ,  1080 ,  1082 ) which are of the type (P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 , P 0 , P 1 , P 2 , P 3 ), respectively, and which convey information (A N-1 , B N-2 , C N-2 , D N-2 , A N-2 , B N-1 , C N-2 , D N-2 , A N-2 , B N-2 , C N-1 , D N-2 , A N-2 , B N-2 , C N-2 , D N-1 , A N-1 , B N-1 , C N-1 , D N-1 , A N-1 , B N , C N-1 , D N-1 , A N-1 , B N , C N-1 , D N-1 , A N-1 , B N-1 , C N , D N-1 , A N-1 , B N-1 , C N-1 , D N-1 , A N , B N , C N , D N ), respectively. It may be observed that transmission units ( 1004 ,  1014 ,  1024 ,  1034 ,  1044 ,  1054 ,  1064 , and  1074 ) are low rate discovery transmission units as indicated by crosshatch shading, while transmission units ( 1006 ,  1008 ,  1010 ,  1012 ,  1016 ,  1018 ,  1020 ,  1022 ,  1026 ,  1028 ,  1030 ,  1032 ,  1036 ,  1038 ,  1040 ,  1042 ,  1046 ,  1048 ,  1050 ,  1052 ,  1056 ,  1058 ,  1060 ,  1062 ,  1066 ,  1068 ,  1070 ,  1072 ,  1076 ,  1078 ,  1080  and  1082 ) are additional transmission units to be used for high rate discovery. It should be noted, that an additional transmission unit for high rate discovery is designated to carry an information portion that has been previously transmitted via a low rate discovery transmission unit, when it carries a transmission unit. In this example, the information carried on the additional resources associated with high rate discovery does not change until a complete set of low rate discovery information has been transmitted. 
       FIG. 11  is a flowchart  1100  of an exemplary method of operating a communications device, e.g. a wireless terminal, to communicate discovery information, e.g., to broadcast peer discovery information. Operation starts in step  1102  and proceeds to step  1104 . In step  1104 , the communications device stores information defining a peer discovery transmission structure, said structure indicating a plurality of ordered transmission units available for transmitting peer discovery information, said stored information including information indicating transmission units to be used for low rate discovery transmissions and additional transmission units to be used for high rate discovery transmissions, said information indicating more transmission units for high rate discovery transmissions than for low rate discovery transmissions. For example, in some exemplary embodiments, there are 4 additional transmission units for each low rate discovery transmission unit in the peer discovery transmission structure. See  FIG. 5 . Other peer discovery structures may have different ratios between the number of additional transmission units associated with high rate discovery and the number of number of transmission units associated with low rate discovery. Operation proceeds from step  1104  to step  1106 . 
     In step  1106 , the communications device transmits a first portion of a set of peer discovery information using a transmission unit corresponding to said low rate discovery transmissions. In some embodiments, the set of peer discovery information including the first portion includes a total of K portions, where K is a positive integer greater than or equal to 2. In some examples there are 4 portions in a set of peer discovery information. For example one set of 4 is the set {portion A N , portion B N , portion C N , portion D N }. Operation proceeds from step  1106  to step  1108 . 
     In step  1108 , the communications device transmits a previously transmitted portion of a set of peer discovery information using a transmission unit corresponding to said high rate discovery transmissions. Operation proceeds from step  1108  to step  1110 . 
     In step  1110  the communications device transmits K−1 additional portions of peer discovery information using transmission units corresponding to high rate discovery transmissions. Operation proceeds from step  1110  to step  1112   
     Then, in step  1112 , the communications device transmits another portion of peer discovery information using another transmission unit corresponding to said low rate discovery transmissions. 
     A first example in accordance with the method of flowchart  1100  will now be described. In a first example, consider  FIG. 9 , and assume that the communications device stores peer discovery transmission structure information in accordance with the pattern of  FIG. 9  (step  1104 ). Also assume that the communications device is in a high rate discovery transmit mode and is transmitting using each of the illustrated discovery transmission units indicated in  FIG. 9 . The first portion transmitted in step  1106  is, e.g., portion A N  in the set of {A N , B N , C N , D N } and is transmitted using the low rate discovery transmission resource indicated by arrow  944 . In this example assume that a set of discovery information has K portions, where K=4. The previously transmitted portion transmitted in step  1108  is, e.g., portion B N-1 , which belongs to the set of {A N-1 , B N-1 , C N-1 , D N-1 } and is transmitted using the high rate discovery transmission resource indicated by arrow  946 . In this example, the previously transmitted portion of step  1108  corresponds to different set of peer discovery information than the set which includes the first portion of step  1106 . Continuing with the example, the K−1 additional portions transmitted in step  1110  are, e.g., the three portions C N-1 , D N-1 , A N  transmitted using transmission units corresponding to high rate discovery transmissions as indicated by arrows  948 ,  950 , and  952 . Continuing with the example, the another portion transmitted in step  1112  is, e.g., portion B N  which is transmitted using another transmission unit corresponding to low rate discovery transmissions as indicated by arrow  954 . 
     A second example in accordance with the method of flowchart  1100  will now be described. In the second example, consider  FIG. 9 , and assume that the communications device stores peer discovery transmission structure information in accordance with the pattern of  FIG. 9  (step  1104 ). Also assume that the communications device is in a high rate discovery transmit mode and is transmitting using each of the illustrated discovery transmission units indicated in  FIG. 9 . The first portion transmitted in step  1106  is, e.g., portion D N-1  in the set of {A N-1 , B N-1 , C N-1 , D N-1 } and is transmitted using the low rate discovery transmission resource indicated by arrow  934 . In this example assume that a set of discovery information has K portions, where K=4. The previously transmitted portion transmitted in step  1108  is, e.g., portion A N-1 , which belongs to the set of {A N-1 , B N-1 , C N-1 , D N-1 } and is transmitted using the high rate discovery transmission resource indicated by arrow  936 . In this example, the previously transmitted portion of step  1108  corresponds to the same set of peer discovery information as the set which includes the first portion of step  1106 . Continuing with the example, the K−1 additional portions transmitted in step  1110  are, e.g., the three portions B N-1 , C N-1 , D N-1  transmitted using transmission units corresponding to high rate discovery transmissions as indicated by arrows  938 ,  940 , and  942 . In this example, the first portion, the previously transmitted portion and the K−1 additional portions are all from the same set of peer discovery information. Continuing with the example, the another portion transmitted in step  1112  is, e.g., portion A N  which is transmitted using another transmission unit corresponding to low rate discovery transmissions as indicated by arrow  944 . 
     A third example in accordance with the method of flowchart  1100  will now be described. In the third example, consider  FIG. 10 , and assume that the communications device stores peer discovery transmission structure information in accordance with the pattern of  FIG. 10  (step  1104 ). Also assume that the communications device is in a high rate discovery transmit mode and is transmitting using each of the illustrated discovery transmission units indicated in  FIG. 10 . The first portion transmitted in step  1106  is, e.g., portion A N  in the set of {A N , B N , C N , D N } and is transmitted using the low rate discovery transmission resource indicated by arrow  1044 . In this example assume that a set of discovery information has K portions, where K=4. The previously transmitted portion transmitted in step  1108  is, e.g., portion A N-1 , which belongs to the set of {A N-1 , B N-1 , C N-1 , D N-1 } and is transmitted using the high rate discovery transmission resource indicated by arrow  1046 . In this example, the previously transmitted portion of step  1108  corresponds to a different set of peer discovery information as the set which includes the first portion of step  1106 . Continuing with the example, the K−1 additional portions transmitted in step  1110  are, e.g., the three portions C N-1 , D N-1 , A N-1  transmitted using transmission units corresponding to high rate discovery transmissions as indicated by arrows  1048 ,  1050 , and  1052 . In this example, the previously transmitted portion and the K−1 additional portions are all from the same set of peer discovery information. In addition, said previously transmitted portion and said N−1 additional portions are transmitted consecutively using transmission units corresponding to high rate peer discovery transmissions following transmission of said first portion. Continuing with the example, the another portion transmitted in step  1112  is, e.g., portion B N  which is transmitted using another transmission unit corresponding to low rate discovery transmissions as indicated by arrow  1054 . 
       FIG. 12 , comprising the combination of  FIG. 12A  and  FIG. 12B , is a flowchart  1200  of an exemplary method of operating a wireless terminal, e.g., a mobile node supporting peer to peer communications, to communicate discovery information, in accordance with an exemplary embodiment. The wireless terminal is, e.g., one of the peer to peer communications devices ( 102 ,  104 ,  106 ,  108 ,  110 ) of system  100  of  FIG. 1 . 
     The exemplary method of flowchart  1200  starts in step  1202  and proceeds to step  1204 , in which the wireless terminal stores peer to peer timing/frequency structure information as stored recurring peer to peer timing/frequency structure information  1206 . The storing of step  1204  is, e.g., part of a wireless terminal configuration and/or wireless terminal initialization process. The stored peer to peer timing/frequency structure information  1206  includes, e.g., information identifying a plurality of discovery interval air link resources, information associating particular discovery interval air link resources with particular device identifiers and information indicating a discovery interval pattern. The stored recurring peer to peer timing/frequency structure information  1206  defines a peer discovery transmission structure, which includes a plurality of ordered transmission units available for transmitting peer discovery information. Information  1206  includes information indicating transmission units to be used for low rate discovery transmissions and additional transmission units to be used for high rate discovery transmissions, and indicates that more transmission units for high rate discovery transmissions than for low rate discovery transmissions. Information described in  FIGS. 2 ,  3 ,  4 ,  5 ,  9  and/or  10  includes information that may be included as part of stored recurring peer to peer timing/frequency structure information. 
     Operation proceeds from step  1204  to step  1208 , in which the wireless terminal receives a reference signal. For example, the wireless receives a beacon signal, e.g., an OFDM beacon signal, from beacon transmitter  116  of  FIG. 1 , wherein the beacon signal is used to coordinate timing with respect to a peer to peer timing structure being used in system  100 . Operation proceeds from step  1208  to step  1210 . In step  1210 , the wireless terminal determines time with respect to the timing structure based on the received signal of step  1208 . Operation proceeds from step  1210  to steps  1212  and  1216 . 
     In step  1212 , which is performed on an ongoing basis, the wireless terminal maintains timing and outputs current time  1214 , which is utilized in other steps. Returning to step  1216 , in step  1216  the wireless terminal checks and determines whether it acquired and is holding a device ID associated with discovery interval air link resources. If it does not currently hold a device ID associated with discovery interval air link resources, then operation returns to the input of step  1216 , for another check at a later point in time. However, if the wireless terminal does hold a device ID associated with discovery interval resources, then operation proceeds from step  1216  to step  1218  and step  1240 , via connecting node B  1220 . 
     Returning to step  1218 , in step  1218  the wireless terminal processes discovery information  1222 , using current time information  1214 , to create discovery interval transmission portions.  FIGS. 6 and 7  illustrate exemplary processing of discovery information and the generation of discovery interval transmission portions. Operation proceeds from step  1218  to step  1224 , in which the wireless terminal stores discovery interval portions with time tag information as part of stored discovery information sets information  1228 . An example of the output from step  1224  is presented for one set of information which includes stored discovery information transmission portion A  1230 , stored discovery information transmission portion B  1232 , stored discovery information portion C  1234 , stored discovery information portion D  1236 , and stored time tag information  1238 . In other embodiments, a different number of portions may correspond to a set of discovery information. In some embodiments, time tag information is not stored directly with a set of discovery information, but rather indirectly, e.g., with a set of discovery information being stored in a set of memory locations which the wireless terminal associates with an index value, e.g., set N−2, set N−1, set N. Operation proceeds from step  1224  via connecting node A  1226  to step  1218 . 
     Returning to step  1240 , in step  1240 , which is performed on a recurring basis, the wireless terminal identifies, using stored recurring peer to peer timing/frequency structure information  1206  and current time information  1214 , a discovery interval resource associated with the device ID currently being held by the wireless terminal. For each identified discovery interval resource associated with the device identifier being currently held by the wireless terminal, operation proceeds from step  1240  to step  1242 . In step  1242 , the wireless terminal determines the interval resource type of the identified discovery interval resource. If the identified interval resource is determined to be a low rate interval resource, then operation proceeds from step  1242  to step  1244 . However, if the wireless terminal determines that the identified interval resource is an additional interval resource, then operation proceeds from step  1242  to step  1246 . 
     Returning to step  1244 , in step  1244  the wireless terminal identifies a stored discovery interval portion to be transmitted. Inputs to step  1244  include stored recurring peer to peer timing/frequency structure information  1206  and discovery information sets including discovery information portions  1228 . Operation proceeds from step  1244  to step  1252 . In step  1252  the wireless terminal generates a signal conveying the identified stored discovery interval portion to be transmitted from step  1244 . Then, in step  1254  the wireless terminal transmits the generated signal conveying the identified discovery interval portion in accordance with the peer to peer timing structure during the discovery interval using the air link resource, e.g., segment, dedicated to the device ID currently being held by the wireless terminal. 
     Returning to step  1246 , in step  1246  the wireless terminal determines the wireless terminal mode of operation with regard to transmitting discovery information. If the wireless terminal is in low rate discovery transmit mode, then operation proceeds from step  1246  to step  1248 , where the device is controlled to refrain from transmitting during the discovery interval. However, if the device is in high rate discovery transmit mode, then operation proceeds from step  1246  to step  1250 . In step  1250 , the wireless terminal identifies a stored discovery interval portion to be transmitted, said identified portion being a previously transmitted portion. Stored recurring peer to peer timing/frequency structure information  1206  and discovery information sets including discovery information portions  1228  are inputs to step  1250 . 
     Operation proceeds from step  1250  to step  1256 . In step  1256  the wireless terminal generates a signal conveying the identified stored discovery interval portion to be transmitted from step  1250 . Then in step  1258 , the wireless terminal transmits the generated signal conveying the identified previously transmitted discovery interval portion from step  1250  in accordance with the peer to peer timing/frequency structure during the discovery interval using the air link resource, e.g., segment, dedicated to the device ID being held by the wireless terminal. 
     In some embodiments, when in high rate discovery transmit mode, the wireless terminal executes  1  iteration of steps  1244 ,  1252  and  1254  for K iterations of steps  1250 ,  1256  and  1258 . For example, in one exemplary embodiment where discovery information in generated in sets of 4 portions, there is 1 iteration of step  1244 ,  1252  and  1254  corresponding to 4 iterations of steps  1250 ,  1256  and  1258 . 
     The operational flows described with respect to steps  1218 ,  1224 ,  1240 ,  1242 ,  1244 ,  1246 ,  1248 ,  1250 ,  1252 ,  1254 ,  1256  and  1258  are continued while the wireless terminal continues to hold a device identifier associated with discovery interval resources. However, if the wireless terminal relinquishes a currently held device identifier associated with discovery interval resources, then the operations with regard to steps  1218 ,  1224 ,  1240 ,  1242 ,  1246 ,  1248 ,  1250 ,  1252 ,  1254 ,  1256  and  1258  are suspended, and operation returns to the input of step  1216 . 
       FIG. 13  is a drawing of an exemplary wireless terminal  1300 , e.g., a peer to peer mobile node which transmits discovery information, in accordance with an exemplary embodiment. Wireless terminal  1300  is, e.g., one of the peer to peer communications devices ( 102 ,  104 ,  106 ,  108 ,  110 ) of system  100  of  FIG. 1 . Exemplary wireless terminal  1300  includes a wireless receiver module  1302 , a wireless transmitter module  1304 , user I/O devices  1308 , a processor  1306 , a memory  1310  coupled together via a bus  1312  over which the various elements may interchange data and information. In some embodiments, wireless terminal  1300  also include network interface  1307  for coupling the wireless terminal to other network nodes and/or the Internet, e.g., via a wired backhaul network. 
     Memory  1310  includes routines  1318  and data/information  1320 . The processor  1306 , e.g., a CPU, executes the routines  1318  and uses the data/information  1320  in memory  1310  to control the operation of the wireless terminal  1300  and implement methods, e.g., the method of flowchart  1100  of  FIG. 11  or the method of flowchart  1200  of  FIG. 12 . 
     Wireless receiver module  1302 , e.g., an OFDM or CDMA receiver, is coupled to receive antenna  1314  via which the wireless terminal  1300  receives a timing reference signal, e.g., a beacon signal, used to synchronize to a peer to peer timing structure. Wireless receiver module  1302  also receives discovery information signals conveying discovery information portions from other wireless terminals which are the source of discovery information and/or from other nodes, e.g., assist nodes and/or server nodes which are assisting peer discovery by retransmitting portions of low rate peer discovery information. 
     Wireless transmitter module  1304 , e.g., an OFDM or CDMA transmitter, is coupled to transmit antenna  1316  via which the wireless terminal  1300  transmits discovery signals. In low rate discovery transmit mode the wireless terminal  1300  transmits discovery information portions during low rate discovery intervals using low rate discovery interval transmission units associated with an identifier that it currently holds, while it refrains from transmitting discovery information portions during additional discovery intervals associated with the identifier that it currently holds. In high rate discovery mode the wireless terminal  1300  transmits discovery signal portions during the low rate discovery intervals using low rate discovery interval transmission units associated with the identifier that it currently holds and transmits discovery signal portions during the additional discovery intervals using the additional discovery interval transmission units associated with the identifier that it currently holds. 
     User I/O devices  1308  include, e.g., a microphone, keyboard, keypad, switches, camera, speaker, display, etc. User I/O devices  1308  allow a user of wireless terminal  1300  to input data/information, access output data/information, and control at least some functions of the wireless terminal, e.g., initiate the broadcasting of one or more types of discovery information. Network interface  1307 , where included, allows the wireless terminal  1300  to be coupled to other network nodes and/or the Internet via a backhaul network. 
     Routines  1318  include a communications routine  1322  and control routines  1324 . The communications routine  1322  implements the various communications protocols used by the wireless terminal  1300 . The control routines  1324  include a low rate control module  1326 , a high rate control module  1328 , a timing structure storage module  1330 , a timing synchronization module  1332 , a timing maintenance module  1334 , a device ID module  1336 , a discovery information processing module  1338 , a discovery information portion storage module  1340 , a discovery interval identification module  1342 , a interval type determination module  1344 , a mode determination module  1346 , a low rate interval portion identification module  1348 , an additional interval portion identification module  1350 , and a discovery signal generation module  1352 . 
     Data/information  1320  includes stored timing/frequency structure information  1354 , information identifying a currently held device identifier associated with discovery air link resources  1378 , current time information  1368 , discovery information to be communicated  1370 , stored discovery information sets  1380 , information identifying the current discovery information transmit mode  1372 , an identified portion to be transmitted  1374 , and a generated discovery signal  1376 . Stored discovery information sets  1380  includes a most recent discovery information set  1382 , e.g., set N, and older generated discovery information sets such older discovery information set  1384 , e.g., set N−L, where N and L are integers. Each set of generated discovery information to be transmitted includes multiple portions. In this exemplary embodiment, set  1380  includes 4 portions (discovery information TX portion A  1386 , discovery information TX portion B  1388 , discovery information TX portion C  1390 , discovery information TX portion D  1392 ). 
     The stored timing/frequency structure information  1354  includes a plurality of sets of information identifying peer discovery interval air link resources corresponding to different identifiers which may be temporarily associated with wireless terminal  1300  (information identifying peer discovery interval resources for device identifier ID  1   1356 , . . . , information identifying peer discovery interval resources for device identifier ID M  1358 ), and mapping pattern information  1367 . Information identifying peer discovery interval resources for device identifier ID  1   1356  includes information identifying low rate peer discovery interval transmission units associated with device ID  1   1360  and information identifying additional discovery interval transmission units associated with device ID  1   1362 . Similarly, information identifying peer discovery interval resources for device identifier ID M  1358  includes information identifying low rate peer discovery interval transmission units associated with device identifier M  1364  and information identifying additional discovery interval transmission units associated with device identifier M  1366 . Mapping pattern information  1367  includes information defining a mapping pattern of generated discovery portions to particular transmission units. Information described with respect to  FIGS. 2 ,  3 ,  4 ,  5 ,  9  and/or  10  includes exemplary information included as part of the timing/frequency structure information  1354 . 
     The stored timing/frequency structure information  1354  includes information defining a peer discovery transmission schedule, the structure indicating a plurality of ordered transmission units available for transmitting peer discovery information, the stored information including information indicating transmission units to be used for low rate discovery transmissions and additional transmission units to be used for high rate discovery transmissions, the stored information indicating more transmission units for high rate discovery transmissions than for low rate discovery transmissions. Information identifying low rate peer discovery interval transmission units  1360  identifies fewer transmission units, e.g., segments, than information identifying additional discovery interval transmission units  1362 . Similarly, information identifying low rate peer discovery interval transmission units  1364  identifies fewer transmission units, e.g., segments, than information identifying additional discovery interval transmission units  1366 . In one embodiment, the ratio between low rate peer discovery transmission units to additional transmission units is 1:4. See  FIG. 5 . 
     Low rate control module  1326  controls the wireless transmitter module  1304  to transmit a portion of peer discovery information in a set of peer discovery information using a transmission unit corresponding to a low rate discovery transmission. For example, consider that wireless terminal  1300  currently holds device identifier ID M, low rate control module  1354  controls the wireless transmitter module  1304  to transmit a discovery portion during an interval identified by information  1364  using a transmission unit identified by information  1364 . 
     High rate control module  1328  controls the wireless transmitter module  1304  to transmit a previously transmitted portion of a set of peer discovery information using a transmission unit corresponding to high rate discovery transmissions. For example, consider that the wireless terminal  1300  currently holds device identifier ID M, high rate control module  1328  controls the wireless transmitter module  1304  to transmit a discovery portion during an interval identified by information  1366  using a transmission unit identified by information  1366 , wherein a discovery information portion transmitted during an additional discovery interval has been previously transmitted during a prior low rate discovery interval. 
     Timing structure storage module  1330  stores information defining a peer discovery transmission structure, e.g., a recurring timing/frequency structure. In some embodiments, the storage is part of a device configuration operation and/or device initialization operation. Stored timing/frequency structure information  1354  represents an output of module  1330 . The stored timing structure information  1354  includes information indicating a plurality of ordered transmission units available for transmitting peer discovery information, the stored information including information indicating transmission units to be used for low rate discovery transmissions and additional transmission units to be used for high rate discovery transmissions, the stored information indicating more transmission units for high rate discovery transmission than for low rate discovery transmissions. 
     Timing synchronization module  1332  synchronizes internal timing within wireless terminal  1300  with respect to an external reference, e.g., a received beacon signal, such that wireless terminal  1300  has its timing within the peer to peer recurring timing structure coordinated with respect to other peer to peer devices in the vicinity. Timing maintenance module  1334  maintains timing within wireless terminal  1300  on an ongoing basis, outputting current time information  1368 . 
     Device ID module  1336  performs functions including acquiring a device identifier associated with a set of discovery interval air link resources to be used temporarily by wireless terminal  1300 , determining whether or not wireless terminal  1300  currently holds such a device identifier, and relinquishing a currently held device identifier. 
     Discovery information processing module  1338  processes discovery information to be communicated  1370  to create discovery interval transmission portions. In some embodiments, the processing of module  1338  includes performing a secure hash function operation.  FIG. 6  and  FIG. 7  illustrate exemplary processing that may be performed by module  1338 . Discovery information portion storage module  1340  stores the processing outputs from module  1338  in stored discovery information sets  1380 . 
     Discovery information identification module  1342  determines whether or not a discovery interval air link resource in the recurring peer to peer timing/frequency structure is associated with a device identifier currently held by wireless terminal  1300 . Interval type determination module  1344  determines whether a discovery interval air link resource is a low rate peer discovery interval air link resource or an additional discovery interval air link resource. Mode determination module  1346  determines the current mode  1372  of wireless terminal  1300  with regard to the transmission of discovery information, e.g., (i) a low rate discovery information transmit mode in which the wireless terminal  1300  transmits discovery information portions using low rate peer discovery interval air link resources but does not use additional discovery interval air link resources or (ii) a high rate discovery information transmit mode in which the wireless terminal  1300  transmits discovery information portions using both low rate peer discovery interval air link resources and additional discovery interval air link resources. The discovery interval air link resources are sometimes referred to alternatively as discovery interval transmission units or discovery interval segments. 
     Low rate portion identification module  1348  identifies a stored discovery interval portion to be transmitted during a low rate peer discovery interval by wireless terminal  1300  from the stored discovery information  1380  in accordance with the stored timing/frequency structure information  1354 . Additional interval portion identification module  1350  identifies a stored discovery interval portion to be transmitted during an additional discovery interval by wireless terminal  1300  from the stored discovery information  1380  in accordance with the stored timing/frequency structure information  1354 . A portion identified to be transmitted during an additional discovery interval is a portion which has been previously transmitted during a prior low rate peer discovery interval. Identified portion to be transmitted  1374  can be an output of either module  1348  or module  1350 , and it is an input to discovery signal generation module  1352 . Discovery signal generation module  1352  generates a discovery signal to convey an identified discovery interval portion to be transmitted. Generated discovery signal  1376  is an output of module  1352 . 
     Wireless transmitter module  1302  transmits portions of peer discovery information. The low rate control module  1326  controls the wireless transmitter module  1302  to transmit a first portion of a set of peer discovery information using a transmission unit corresponding to low rate discovery transmissions. The high rate control module  1328  controls the wireless transmitter module  1302  to transmit a previously transmitted portion of a set of peer discovery information using a transmission unit corresponding to high rate discovery transmissions. For some cases, the previously transmitted portion of a set of peer discovery information corresponds to a different set of peer discovery information than the set of peer discovery information which includes the first portion. For some other cases, the previously transmitted portion of a set of peer discovery information corresponds to the same set of peer discovery information as the first portion. The high rate control module  1328  controls the wireless transmitter module  1302  to transmit a previously transmitted portion following transmission of the first portion. At times, transmitting a previously transmitted portion precedes transmission of another portion of peer discovery information using another transmission unit corresponding to low rate discovery transmissions. 
     In various embodiments, the set of peer discovery information including the first portion includes a total of K portions, e.g., 4 portions. In some such embodiments, the wireless transmitter module  1302  is also for transmitting additional portions of peer discovery information in addition to said first portion and said previously transmitted portion. In some such embodiments, the high rate control module controls the wireless transmitter module  1302  to transmit K−1 additional portions of peer discovery information using transmission units corresponding to high rate discovery transmissions following transmission of said first portion and prior to transmission of said another portion. For example, consider that K=4. The wireless terminal  1300  transmits in order: (i) the first portion using a first low rate discovery transmission unit; (ii) a previously transmitted discovery portion using a first additional transmission unit associated with high rate transmissions; (iii) a second previously transmitted discovery portion using a second additional transmission unit associated with high rate transmissions; (iv) a third previously transmitted discovery portion associated with high rate transmissions; (v) a fourth previously transmitted discovery portion associated with high rate transmissions; and (vi) a second portion using a second low rate discovery transmission unit. The transmission sequence is such that during some times, the first portion transmitted using a low rate discovery transmission unit and the K−1 discovery portions using high rate discovery transmission units are all from the same set of peer discovery information. 
     In some embodiments, the previously transmitted portion and the K−1 additional portions are controlled to be transmitted consecutively using transmission units corresponding to high rate peer discovery transmissions following transmission of the first portion using a low rate discovery transmission unit. For some embodiments, the previously transmitted portion and the K−1 additional portions are all from the same set of peer discovery information. Refer to the example of  FIG. 10 . In some other embodiments, during some intervals of the recurring structure, the previously transmitted portion and the K−1 additional portions are from the same set of peer discovery information, while for other intervals in the recurring structure the previously transmitted portion and the K−1 additional portions include members from two different sets of discovery information. Refer to  FIG. 9 . 
       FIG. 14  is a drawing  1400  illustrating exemplary nodes in a peer to peer communications system and the transmission of discovery information. The exemplary nodes are, e.g., any of the peer to peer communications devices ( 102 ,  104 ,  106 ,  108 ,  110 ) of  FIG. 1 . The exemplary nodes include a first wireless terminal  1402 , e.g., a peer to peer mobile node, which is operating in a high rate discovery mode and which is transmitting discovery information at a high rate, as indicated by discovery signals  1412  being transmitted along time axis  1410 . The exemplary nodes also include a second wireless terminal  1404 , e.g., a second peer to peer mobile node, which is operating in a low rate discovery mode and which is transmitting discovery information at a low rate, as indicated by discovery signals  1414  being transmitted along time axis  1410 . The exemplary nodes also include a third wireless terminal  1406 , e.g., a third peer to peer mobile node, which is operating during a first time in a high rate discovery mode and is transmitting discovery information at a high rate, but then changes to operate in a low rate discovery mode and transmits discovery information at a low rate, as indicated by discovery signals  1416  being transmitted along time axis  1410 . In some embodiments, at least some of the wireless terminals perform discovery information transmissions in one mode but not the other. In some embodiments, at least some of the wireless terminals are multi-mode with regard to the transmission of discovery information, e.g., transmitting at high rate at some times while transmitting at a low rate at other times. 
     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., 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 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. 
     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, storing information defining a peer discovery transmission structure, transmitting a first portion of a set of peer discovery information using a transmission unit corresponding to said low rate discovery transmissions and/or transmitting a previously transmitted portion of a set of peer discovery information using a transmission unit corresponding to said high rate discovery transmissions. 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 are configured to perform the steps of the methods described as being 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. 
     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 access nodes and mobile nodes. In some embodiments the access nodes are implemented as base stations which establish communications links with mobile nodes using OFDM and/or CDMA. In various embodiments the mobile nodes are implemented as notebook computers, personal data assistants (PDAs), or other portable devices including receiver/transmitter circuits and logic and/or routines, for implementing the methods.