# US 8,787,323 B2 · Wireless communication methods and apparatus supporting synchronization

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- Number: US 8,787,323 B2
- Document ID: US8787323B2
- Status: Granted
- Kind: B2
- Application number: 11/621,966
- Filed: 2007-01-10
- Published: 2008-02-14
- Granted: 2014-07-22
- Earliest claimed: 2006-01-11
- Assignees: QUALCOMM Incorporated
- Applicants: Rajiv Laroia; Frank A. Lane; Junyi Li; Tom Richardson
- Inventors: Rajiv Laroia; Frank A. Lane; Junyi Li; Tom Richardson
- Web page: https://patentgrep.com/patent/US8787323B2

## CPC

- H04W 40/244: {using a network of reference devices, e.g. beaconing}
- H04L 5/0016: {Time-frequency-code}
- H04L 5/0035: {Resource allocation in a cooperative multipoint environment}
- H04L 27/261: {Details of reference signals}
- H04W 8/005: {Discovery of network devices, e.g. terminals}
- H04W 16/14: Spectrum sharing arrangements {between different networks}
- H04W 36/16: Performing reselection for specific purposes
- H04W 48/20: Selecting an access point
- H04W 52/0229: {where the received signal is a wanted signal}
- H04W 72/02: Selection of wireless resources by user or terminal
- H04W 88/10: adapted for operation in multiple networks, e.g. multi-mode access points
- H04J 3/0602: {Systems characterised by the synchronising information used}
- H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)}
- H04L 27/2601: {Multicarrier modulation systems}
- H04W 28/04: Error control
- H04W 28/18: Negotiating wireless communication parameters
- H04W 40/24: Connectivity information management, e.g. connectivity discovery or connectivity update
- H04W 48/08: Access restriction or access information delivery, e.g. discovery data delivery (signalling during connection H04W76/00)
- H04W 48/16: Discovering, processing access restriction or access information
- H04W 52/04: Transmission power control [TPC]
- H04W 76/14: Direct-mode setup
- H04W 84/042: {Public Land Mobile systems, e.g. cellular systems}
- H04W 84/18: Self-organising networks, e.g. ad-hoc networks or sensor networks
- H04W 88/02: Terminal devices
- H04W 88/04: adapted for relaying to or from another terminal or user
- H04W 88/06: adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals
- Y02D 30/70: in wireless communication networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

Peer to peer communication timing, e.g., for an ad hoc network, is referenced with respect to an external broadcast signal from a terrestrial or satellite based transmitter. Wireless terminals, seeking to communicate via peer to peer communications, receive the reference broadcast signal, and set their internal timing structure with respect to the reference signal. This facilitates peer to peer timing coordination. A wireless terminal transmits a signal, e.g., a user beacon signal identifying its presence, during a time interval during which another wireless terminal is expected to be monitoring. Reference signal based coordinated timing and use of user beacon signals allows the wireless terminals to maintain situational awareness and coordinate peer to peer communications, while keeping power consumption low, since wireless terminal modules can be powered down during predetermined intervals in the coordinated timing structure where the wireless terminal does not need to transmit and/or receive.

## Claims

### Claim 1

A method of operating a wireless terminal to communicate with another communications device, the method comprising:
receiving a first reference signal from a first communications band, said first reference signal being an OFDM beacon signal from a first communications device which broadcasts the first reference signal on a recurring basis but which does not transmit user data to a wireless terminal, said first communications device and said another communications device being different communications devices, said first communications device being a non-access device, said non-access device being an OFDM beacon transmitter device which does not operate as a base station;
determining, based on said first reference signal, a first time interval to be used for transmitting a second signal to said another communications device; and
transmitting a second signal to said another communications device during said time interval.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
determining, based on said first reference signal, a second time interval to be used for receiving signals from devices other than said first communications device, said second time interval being different from the first time interval.

### Claim 3 (depends on 1)

The method of claim 1,
wherein transmitting said second signal includes transmitting said second signal in a second communications band which is different from said first communications band.

### Claim 4 (depends on 3)

The method of claim 3, wherein beacon signals transmitted by said first communications device are transmitted using a free running timing which is not coordinated with respect to other non-access beacon signal transmitters and base stations.

### Claim 5 (depends on 4)

The method of claim 4, further comprising:
determining, prior to transmitting the second signal, the second communications band based on the first received reference signal; and
wherein the first and second bands are partially overlapping frequency bands.

### Claim 6 (depends on 1)

The method of claim 1, further comprising:
prior to transmitting said second signal, generating said second signal as a function of one of a device identifier corresponding to said wireless terminal and a user identifier corresponding to a user of said wireless terminal.

### Claim 7 (depends on 6)

The method of claim 6, further comprising:
determining at least one additional transmit time as a function of a parameter derived from said first reference signal.

### Claim 8 (depends on 7)

The method of claim 7, wherein determining at least one additional transmit time includes using a time hopping function which uses said parameter as an input parameter.

### Claim 9 (depends on 8)

The method of claim 8, wherein said time hopping function further uses as an input a second parameter derived from another signal received from said first communications device.

### Claim 10 (depends on 2)

The method of claim 2, further comprising:
establishing a peer to peer communications session with said another device using timing synchronization information derived from said first reference signal.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
exchanging user data as part of said peer to peer communications session, said user data including at least one of voice data, text data and image data, said peer to peer communications session being conducted directly between said wireless terminal and said another device over a direct air link.

### Claim 12 (depends on 1)

The method of claim 1, further comprising:
prior to transmitting said second signal, deriving frequency information from the received first reference signal; and
determining at least one transmit frequency to be used for transmitting said second signal from the derived frequency information.

### Claim 13 (depends on 1)

The method of claim 1, wherein said second signal includes a beacon signal burst.

### Claim 14 (depends on 1)

The method of claim 1, wherein said second signal is a pseudo noise sequence signal transmitted over the frequency spectrum of said second frequency band.

### Claim 15 (depends on 1)

The method of claim 1, wherein said second signal is an OFDM signal.

### Claim 16 (depends on 4)

The method of claim 4, wherein said second signal is an OFDM signal.

### Claim 17 (depends on 1)

The method of claim 1, wherein said first reference signal is a satellite broadcast signal and said second signal is a terrestrial broadcast signal.

### Claim 18 (depends on 1)

The method of claim 1, wherein said wireless terminal is a mobile handset.

### Claim 19

A wireless communications device for communicating with another communications device, comprising:
a receiver for receiving a first reference signal from a first communications band, said first reference signal being an OFDM beacon signal from a first communications device which broadcasts the first reference signal on a recurring basis but which does not transmit user data to a wireless terminal, said first communications device and said another communications device being different communications devices, said first communications device being a non-access device, said non-access device being an OFDM beacon transmitter device which does not operate as a base station;
a transmission interval timing determination module for determining, based on said first reference signal, a first time interval to be used for transmitting a second signal to said another communications device; and
a transmitter for transmitting said second signal to said another communications device during said determined time interval.

### Claim 20 (depends on 19)

The wireless communications device of claim 19, further comprising:
a receive interval timing determination module for determining, based on said first reference signal, a second time interval to be used for receiving signals from devices other than said first communications device, said second time interval being different from the first time interval.

### Claim 21 (depends on 19)

The wireless communications device of claim 19, further comprising:
a transmission band control module to transmit said second signal in a second communications band which is different from said first communications band.

### Claim 22 (depends on 21)

The wireless communications device of claim 21, wherein beacon signals transmitted by said first communications device are transmitted using a free running timing which is not coordinated with respect to other non-access beacon signal transmitters and base stations.

### Claim 23 (depends on 22)

The wireless communications device of claim 22, further comprising:
a peer to peer communications band determination module for determining, prior to transmitting the second signal, the second communications band based on the first received reference signal; and
wherein the first and second bands are non-overlapping frequency bands.

### Claim 24 (depends on 22)

The wireless communications device of claim 22, wherein the first and second bands are partially overlapping frequency bands.

### Claim 25 (depends on 19)

The wireless communications device of claim 19, further comprising:
a second signal generation module for generating second signal, prior to transmitting said second signal, as a function of one of a device identifier corresponding to said wireless communications device and a user identifier corresponding to a user of said wireless communications device.

### Claim 26 (depends on 25)

The wireless communication device of claim 25, further comprising:
additional transmit time determination module for determining at least one additional transmit time as a function of a parameter derived from said first reference signal.

### Claim 27 (depends on 26)

The wireless communications device of claim 26, wherein said additional transmit time determination module uses a time hopping function which uses said parameter as an input parameter.

### Claim 28 (depends on 27)

The wireless communications device of claim 27, wherein said time hopping function further uses as an input a second parameter derived from another signal received from said first communications device.

### Claim 29 (depends on 20)

The wireless communications device of claim 20, further comprising:
a peer to peer communications establishment module for establishing a peer to peer communications session with said another device using timing synchronization information derived from said first reference signal.

### Claim 30 (depends on 29)

The wireless communications device of claim 29, further comprising:
a peer to peer session management module for controlling the exchange of user data as part of said peer to peer communications session, said user data including at least one of voice data, text data and image data, said peer to peer communications session being conducted directly between said wireless communications device and said another device over a direct air link.

### Claim 31 (depends on 19)

The wireless communications device of claim 19, further comprising:
a frequency information recovery module for recovering conveyed frequency information from the first reference signal prior to transmitting said second signal, deriving frequency information from the received first reference signal; and
a transmission frequency determination module for determining at least one transmit frequency to be used for transmitting said second signal from the derived frequency information.

### Claim 32 (depends on 19)

The wireless communications device of claim 19, wherein said second signal includes a beacon signal burst.

### Claim 33 (depends on 19)

The wireless communications device of claim 19, wherein said second signal is a pseudo noise sequence signal transmitted over the frequency spectrum of said second frequency band.

### Claim 34 (depends on 19)

The wireless communications device of claim 19, wherein said second signal is an OFDM signal.

### Claim 35 (depends on 22)

The wireless communications device of claim 22, wherein said second signal is an OFDM signal.

### Claim 36 (depends on 19)

The wireless communications device of claim 19, wherein said first reference signal is a satellite broadcast signal and said second signal is a terrestrial broadcast signal.

### Claim 37 (depends on 19)

The wireless communications device of claim 19, wherein said wireless communications device is a mobile handset.

### Claim 38

A wireless communications device for communicating with another communications device, comprising:
receiver means for receiving a first reference signal from a first communications band, said first reference signal being an OFDM beacon signal from a first communications device which broadcasts the first reference signal on a recurring basis but which does not transmit user data to a wireless terminal, said first communications device and said another communications device being different communications devices, said first communications device being a non-access device, said non-access device being an OFDM beacon transmitter device which does not operate as a base station;
means for determining, based on said first reference signal, a first time interval to be used for transmitting a second signal to said another communications device; and
means for transmitting said second signal to said another communications device during said determined time interval.

### Claim 39 (depends on 38)

The wireless communications device of claim 38, further comprising:
receive interval timing determination means for determining, based on said first reference signal, a second time interval to be used for receiving signals from devices other than said first communications device, said second time interval being different from the first time interval.

### Claim 40 (depends on 38)

The wireless communications device of claim 38, further comprising:
transmission band control means for determining a second communications band in which to transmit said second signal, said second communications band being different from said first communications band.

### Claim 41 (depends on 40)

The wireless communications device of claim 40, wherein beacon signals transmitted by said first communications device are transmitted using a free running timing which is not coordinated with respect to other non-access beacon signal transmitters and base stations.

### Claim 42 (depends on 41)

The wireless communications device of claim 41, further comprising:
a peer to peer communications band determination means for determining, prior to transmitting the second signal, the second communications band based on the first received reference signal; and
wherein the first and second bands are non-overlapping frequency bands.

### Claim 43 (depends on 41)

The wireless communications device of claim 41, wherein the first and second bands are partially overlapping frequency bands.

### Claim 44 (depends on 38)

The wireless communications device of claim 38, further comprising:
second signal generation means for generating said second signal, prior to transmitting said second signal, as a function of one of a device identifier corresponding to said wireless communications device and a user identifier corresponding to a user of said wireless communications device.

### Claim 45 (depends on 44)

The wireless communications device of claim 44, further comprising:
additional transmit time determination means for determining at least one additional transmit time as a function of a parameter derived from said first reference signal.

### Claim 46 (depends on 45)

The wireless communications device of claim 45, wherein said additional transmit time determination means uses a time hopping function which uses said parameter as an input parameter.

### Claim 47 (depends on 46)

The wireless communications device of claim 46, wherein said time hopping function further uses as an input a second parameter derived from another signal received from said first communications device.

### Claim 48 (depends on 39)

The wireless communications device of claim 39, further comprising:
peer to peer communications establishment means for establishing a peer to peer communications session with said another device using timing synchronization information derived from said first reference signal.

### Claim 49 (depends on 48)

The wireless communications device of claim 48, further comprising:
peer to peer session management means for controlling the exchange of user data as part of said peer to peer communications session, said user data including at least one of voice data, text data and image data, said peer to peer communications session being conducted directly between said wireless communications device and said another device over a direct air link.

### Claim 50 (depends on 38)

The wireless communications device of claim 38, further comprising:
frequency information recovery means for recovering conveyed frequency information from the first reference signal prior to transmitting said second signal, deriving frequency information from the received first reference signal; and
transmission frequency determination means for determining at least one transmit frequency to be used for transmitting said second signal from the derived frequency information.

### Claim 51

A non-transitory computer readable medium embodying machine executable instructions for controlling a wireless terminal to implement a method of communicating with another communications device, the method comprising:
receiving a first reference signal from a first communications band, said first reference signal being an OFDM beacon signal from a first communications device which broadcasts the first reference signal on a recurring basis but which does not transmit user data to a wireless terminal, said first communications device and said another communications device being different communications devices, said first communications device being a non-access device, said non-access device being an OFDM beacon transmitter device which does not operate as a base station;
determining, based on said first reference signal, a first time interval to be used for transmitting a second signal to said another communications device; and
transmitting a second signal to said another communications device during said time interval.

### Claim 52 (depends on 51)

The non-transitory computer readable medium of claim 51, further embodying machine executable instructions for:
determining, based on said first reference signal, a second time interval to be used for receiving signals from devices other than said first communications device, said second time interval being different from the first time interval.

### Claim 53 (depends on 51)

The non-transitory computer readable medium of claim 51, wherein said non-transitory computer readable medium further comprises machine executable instructions for:
controlling transmitting said second signal in a second communications band which is different from said first communications band, as part of said step of transmitting said second signal.

### Claim 54 (depends on 53)

The non-transitory computer readable medium of claim 53, wherein beacon signals transmitted by said first communications device are transmitted using a free running timing which is not coordinated with respect to other non-access beacon signal transmitters and base stations.

### Claim 55 (depends on 54)

The non-transitory computer readable medium of claim 54, further embodying machine executable instructions for:
determining, prior to transmitting the second signal, the second communications band based on the first received reference signal; and
wherein the first and second bands are partially overlapping frequency bands.

### Claim 56 (depends on 51)

The non-transitory computer readable medium of claim 51, further embodying machine executable instructions for:
prior to transmitting said second signal, generating said second signal as a function of one of a device identifier corresponding to said wireless terminal and a user identifier corresponding to a user of said wireless terminal.

### Claim 57

An apparatus comprising:
a wireless terminal processor configured to:
receive a first reference signal from a first communications band, said first reference signal being an OFDM beacon signal from a first communications device which broadcasts the first reference signal on a recurring basis but which does not transmit user data to a wireless terminal, said first communications device and another communications device being different communications devices, said first communications device being a non-access device, said non-access device being an OFDM beacon transmitter device which does not operate as a base station;
determine, based on said first reference signal, a first time interval to be used for transmitting a second signal to said another communications device; and
control transmission of a second signal to said another communications device during said time interval.

### Claim 58 (depends on 57)

The apparatus of claim 57, wherein said wireless terminal processor is further configured to:
determine, based on said first reference signal, a second time interval to be used for receiving signals from devices other than said first communications device, said second time interval being different from the first time interval.

### Claim 59 (depends on 57)

The apparatus of claim 57,
wherein said wireless terminal processor is further configured to:
control transmission of said second signal in a second communications band which is different from said first communications band, as part of said controlling transmission of said second signal.

### Claim 60 (depends on 59)

The apparatus of claim 59, wherein beacon signals transmitted by said first communications device are transmitted using a free running timing which is not coordinated with respect to other non-access beacon signal transmitters and base stations.

### Claim 61 (depends on 60)

The apparatus of claim 60, wherein said wireless terminal processor is further configured to:
determine, prior to transmitting the second signal, the second communications band based on the first received reference signal; and
wherein the first and second bands are partially overlapping frequency bands.

### Claim 62 (depends on 57)

The apparatus of claim 57, wherein said wireless terminal processor is further configured to:
generate said second signal as a function of one of a device identifier corresponding to said apparatus and a user identifier corresponding to a user of said apparatus.