SYNCHRONIZING PEER-TO-PEER OPERATION FOR OUTSIDE NETWORK COVERAGE AND PARTIAL NETWORK COVERAGE USING LTE AIR INTERFACE

• US 20150009949A1
• Filed: 03/26/2014
• Published: 01/08/2015
• Est. Priority Date: 07/08/2013
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Debdeep Chatterjee
• Inventors: Khoryaev, Alexey, Panteleev, Sergey, Shilov, Mikhail A., Chatterjee, Debdeep
• Granted Patent: US 9,379,856 B2
• Time in Patent Office: Days
• US Class Current: 370/330
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04J 11/00 Orthogonal multiplex systems, e.g. using WALSH codesH04J13/00 takes precedence
• CPC Class Codes: H04L 5/0005 Time-frequency
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 40/246 Connectivity information discovery
• CPC Class Codes: H04W 48/00 Access restriction access security to prevent unauthorised access H04W12/08; Network selection; Access point selection
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 72/044 based on the type of the allocated resource
• CPC Class Codes: H04W 72/1215 for collaboration of different radio technologies
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 84/042 Public Land Mobile systems, e.g. cellular systems
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 88/02 : Terminal devices
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

A user equipment (UE) enables synchronous peer-to-peer communication between devices for out of network coverage and partial network coverage scenarios. The UE performs a synchronization procedure and selects a spectrum resource within an uplink (UL) spectrum for device-to-device (D2D) communication. The UE, representing a synchronization source, generates timing information and synchronization signals for synchronizing a group of wireless communication devices (peer UEs) with the UE in a local synchronization area. The UE transmits, in selected or pre-allocated time or frequency resources, a synchronization signal including the timing information in order to synchronize devices in the local synchronization area.

Claims

1. User equipment (UE) comprising processing circuitry to:

select a subchannel of an uplink (UL) subframe for device-to-device (D2D) communication, the subchannel of the UL subframe corresponding to carrier resources of an evolved universal terrestrial radio access network (E-UTRAN);

generate timing information for synchronizing a group of wireless communication devices with the UE in a local synchronization area; and

transmit, in the selected subchannel of the UL subframe, a synchronization signal comprising the timing information.

2. The UE of claim 1, wherein the processing circuitry is further configured to:

receive, from a first wireless communication device in the group, a signal indicating detection of a second wireless communication device outside of the local synchronization area; and

in response to the signal, send a request to the first wireless communication device to extend the local synchronization area by retransmitting the synchronization signal, wherein the UE becomes an independent synchronization source and the first wireless communication device becomes a regional synchronization source that depends from deriving synchronization from the UE.

3. The UE of claim 1, wherein the processing circuitry is further configured to:

receive, from a first wireless communication device in the group, a signal indicating detection of a second wireless communication device outside of the local synchronization area, and that the first wireless communication device autonomously extends the local synchronization area by retransmitting the synchronization signal, wherein the UE becomes an independent synchronization source and the first wireless communication device becomes a regional synchronization source that depends from deriving synchronization from the UE.

4. The UE of claim 1, wherein the processing circuitry is further configured to:

receive, from a first wireless communication device in the group, a request to change the selected subchannel to a different subchannel, timeslot, or subframe to avoid interference with a remote synchronization area that at least partially overlaps with the local synchronization area; and

in response to the request, change transmission of the synchronization signal to the different subchannel, timeslot, or subframe.

5. The UE of claim 1, wherein the processing circuitry is further configured to:

determine interference with a remote synchronization area that at least partially overlaps with the local synchronization area; and

autonomously change transmission of the synchronization signal to a different subchannel, timeslot or subframe.

6. The UE of claim 1, wherein the UE is a first peer radio head configured as a first reference source in the local synchronization area, and wherein the processing circuitry is further configured to:

detect entry of a second peer radio head into the local synchronization area, the second peer radio head configured as a second reference source in a remote synchronization area; and

synchronize with the second radio head to establish a common reference source for the local synchronization area and the remote synchronization area.

7. The UE of claim 6, wherein the processing circuitry is further configured to:

receive, in a different subchannel of the UL subframe, timeslot or subframe, synchronization information from the second peer radio head; and

derive, based on the synchronization information from the second peer radio head, the timing information for synchronizing the group of wireless communication devices in the local synchronization area.

8. The UE of claim 7, wherein the processing circuitry is further configured to:

derive the timing information based on a time of arrival of the synchronization information in the different subchannel, timeslot or subframe.

9. The UE of claim 6, wherein the processing circuitry is further configured to:

determine a round trip time for communicating signals between the first peer radio head and the second peer radio head; and

derive the timing information by compensating for propagation delay based on the round trip time.

10. The UE of claim 7, wherein the processing circuitry is further configured to:

receive synchronization information from a third peer radio head;

determine timing grade information corresponding to propagation conditions and signal quality for the synchronization information from the second peer radio head and for the synchronization information from the third peer radio head; and

select, based on at least one of the timing grade information and a synchronization hop count, whether to continue deriving the timing information based on the synchronization information from the second peer radio head or to start deriving the timing information based on the synchronization information from the third peer radio head.

11. The UE of claim 1, wherein the subchannel of the UL subframe comprises a logical frequency subchannel associated with multiple physical resource blocks (PRBs) configured for frequency division multiplexing.

12. The UE of claim 11, wherein the carrier resources are further divided into time slots or subframes for time division multiplexing.

13. The UE of claim 1, further comprising:

a transceiver including transmitter and receiver components;

multiple antennas, in which a first antenna of the multiple antennas is coupled to the transmitter, and in which a second antenna of the multiple antennas is coupled to the receiver;

a display touchscreen; and

a keyboard.

14. A method for synchronization of user equipment (UE) configured to communicate with a wireless cellular network, the method comprising:

determining that synchronization with and attachment to an evolved Node B (eNodeB) of the wireless cellular network is not currently available;

in response to the determination, scanning for and detecting a plurality of synchronization signals from corresponding peer radio heads;

measuring a signal quality for each of the plurality of synchronization signals;

selecting a first synchronization signal of the plurality of synchronization signals based at least in part on the measured signal quality; and

synchronizing a local timing source with the selected first synchronization signal.

15. The method of claim 14, further comprising:

communicating with a first group of UEs based on synchronization with the first synchronization signal;

determining to extend, to a second group of UEs, the synchronization with the first synchronization signal;

in response to the determination, periodically transmitting a second synchronization signal to the second group of UEs, the second synchronization signal comprising synchronization information derived from the synchronizing of the local timing source with the selected first synchronization signal.

16. The method of claim 15, wherein determining to extend the synchronization with the first synchronization signal to the second group of UEs comprises one or more triggers selected from a group comprising detecting a presence of the second group of UEs, receiving a request for synchronization from at least one UE in the second group of UEs, and receiving a request or synchronization signal from a peer radio head corresponding to the first synchronization signal.

17. The method of claim 14, further comprising:

detecting a subsequent availability of the eNodeB; and

in response to the detected subsequent availability, ceasing synchronization with the first synchronization signal and attaching to the eNodeB.

18. The method of claim 14, wherein determining that synchronization with and attachment to the eNodeB is not currently available comprises:

scanning downlink (DL) resources in an attempt to detect a cellular primary synchronization signal (PSS) and secondary synchronization signal (SSS) transmitted by the eNodeB; and

determining that the PSS and SSS signals are not available from the eNodeB.

19. The method of claim 14, wherein scanning for and detecting the plurality of synchronization signals comprises:

scanning uplink (UL) frequency subchannels over multiple subframes for the plurality of synchronization signals.

20. The method of claim 14, wherein measuring the signal quality comprises measuring, for each detected synchronization signal, one or more parameter selected from a group comprising signal power, signal-to-interference-plus-noise ratio (SINR), a synchronization error, and a standard deviation of synchronization error.

21. The method of claim 14, wherein selecting the first synchronization signal further comprises:

determining synchronization hop count;

determining, for each detected synchronization signal, timing grade information corresponding to propagation conditions and signal quality; and

selecting the first synchronization signal based at least in part on the synchronization hop count and the timing grade information.

22. User equipment (UE) comprising:

a wireless receiver to receive, from a peer UE, synchronization information through a first frequency subchannel, time slot, or subframe;

a local timer;

a processor to synchronize the local timer with the synchronization received through the first frequency subchannel, time slot, or subframe; and

a wireless transmitter to transmit the synchronization information through a second frequency subchannel, time slot, or subframe, wherein the second frequency subchannel, timeslot, or subframe is different than the first frequency subchannel, time slot, or subframe.

23. The UE of claim 22, further comprising:

measurement circuitry to determine a signal quality of the synchronization information received through the first frequency subchannel, time slot, or subframe.

24. The UE of claim 22, wherein the processor is further configured to:

determine a number of hops between UEs within a synchronization the synchronization information made before being received by the peer UE; and

receive timing grade information from the peer UE.

25. The UE of claim 22, wherein the wireless receiver is further configured to receive a round trip time measurement for signals sent between the UE and the peer UE.