SIGNALING AND CHANNEL DESIGNS FOR D2D COMMUNICATIONS

• US 20150049732A1
• Filed: 08/02/2013
• Published: 02/19/2015
• Est. Priority Date: 08/03/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Xue, Feng, Li, Qinghua, Niu, Huaning, Fwu, Jong-Kae
• Granted Patent: US 9,451,604 B2
• Time in Patent Office: Days
• US Class Current: 370/330
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 1/1861 Physical mapping arrangements for ACK signaling see also H04L5/0053
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04W 72/044 based on the type of the allocated resource
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 76/14 Direct-mode setup
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Described are methods and devices for enabling D2D communications with signal structures that require minimal changes to the current LTE architecture. In the embodiments described, the eNB grants resources to UEs for D2D communication and either initiates or permits a pair of UEs to establish a D2D link. Certain embodiments are designed to minimize changes to the current LTE control signaling structure by having the control signaling always come from the eNB as in a normal cellular link so that the transmitting UE transmits over a data channel (e.g., PUSCH/PDSCH) that the receiving UE is able to decode.

Claims

1. A method for operating an evolved Node B (eNB) in an LTE (Long Term Evolution) network, comprising:

selecting first and second user equipments (UEs) for device-to-device (D2D) communications;

allocating a D2D time-frequency resource for the first UE to transmit to the second UE;

assigning the allocated D2D resource as a physical uplink shared channel (PUSCH) resource to the first UE;

assigning the allocated D2D resource as a physical downlink shared channel (PDSCH) resource to the second UE; and

,

receiving a hybrid automatic repeat request (HARQ) ACK/NACK (positive or negative acknowledgement) from the second UE over the physical uplink control channel (PUCCH) in response to data transmitted to the second UE from the first UE.

2. The method of claim 1 further comprising receiving and decoding data transmitted to the second UE from the first UE over the first UE'"'"'s PUSCH.

3. The method of claim 2 further comprising, if the data received from the first UE was decoded incorrectly, transmitting a NACK to the first UE via the physical HARQ indicator channel (PHICH) to indicate to the first UE that the data should be re-transmitted.

4. The method of claim 2 further comprising, if the data received from the first UE was decoded correctly, transmitting an ACK to the first UE via the physical HARQ indicator channel (PHICH) with no resource allocation for further transmission to indicate to the first UE that its transmission buffer should not be flushed.

5. The method of claim 4 further comprising, if a NACK has been received from the second UE, transmitting a resource allocation in the PDCCH to the first UE for further transmission over the PUSCH with a NewData bit not toggled to indicate that the data should be retransmitted in a subsequent subframe.

6. The method of claim 4 further comprising, if an ACK has been received from the second UE and if the first UE has more data to send, transmitting a resource allocation in PDCCH to the first UE for further transmission over the PUSCH with a NewData bit toggled to indicate that new data should be transmitted in a subsequent subframe.

7. The method of claim 1 further comprising forwarding the ACK/NACK received from the second UE to the first UE after a processing delay.

8. The method of claim 7 wherein the processing delay is less than 4 milliseconds.

9. The method of claim 7 wherein the ACK/NACK is forwarded to the first UE via the PHICH.

10. The method of claim 1 further comprising transmitting to the second UE information about the first UE'"'"'s scrambling sequence to enable the second UE to decode the first UE'"'"'s transmitted data.

11. The method of claim 10 further comprising transmitting the first UE'"'"'s RNTI (radio network temporary identity) to the second UE via a PDCCH (physical downlink control channel) resource.

12. The method of claim 1 further comprising allocating D2D resources on a semi-persistent basis to the first and second UEs.

13. The method of claim 1 further comprising transmitting a power level to the first and second UEs to be used for their transmissions.

14. A user equipment (UE) device, comprising:

a radio transceiver to provide an air interface for communicating with an eNB (evolved node B) and for D2D (device-to-device) communications; and

processing circuitry connected to the radio transceiver to;

detect if D2D resources have been made available by the eNB;

if D2D resources are available, transmit control channel signaling to an intended D2D receiver UE using the available D2D resources; and

,

after receiving control signaling from the receiver UE indicating its readiness to receive data, transmit data to the receiver UE using the available D2D resources.

15. The device of claim 14 wherein the processing circuitry is such that the control channel signaling transmitted to the intended D2D receiver UE is transmitted at a power level indicated by the eNB via control channel signaling.

16. The device of claim 14 wherein the processing circuitry is to detect if D2D resources have been made available by the eNB using a separate control channel with a unique RNTI (radio network temporary identifier) dedicated for D2D signaling.

17. The device of claim 14 wherein the processing circuitry is to receive reference signals from the eNB for time and frequency synchronization.

18. A method for operating an evolved Node B (eNB) in an LTE (Long Term Evolution) network, comprising:

making particular time-frequency resources available for device-to-device (D2D) communications, referred to as D2D resources; and

,

transmitting an indication of the available D2D resources to user equipments (UEs) via a separate control channel with a unique RNTI (radio network temporary identifier) dedicated for D2D signaling.

19. The method of claim 18 further comprising transmitting an indication via control signaling of a specified power level that should be used by UEs in transmitting over the D2D resources.

20. The method of claim 18 further comprising transmitting reference signals for time and frequency synchronization via control signaling to UEs utilizing the D2D resources.