LOW LATENCY PHYSICAL LAYER DESIGN FOR CONTENTION-BASED UPLINK CHANNELS

• US 20190029013A1
• Filed: 09/12/2018
• Published: 01/24/2019
• Est. Priority Date: 11/25/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Xu, Hao, Damnjanovic, Aleksandar, Dabeer, Onkar Jayant, Gaal, Peter, Chen, Wanshi, Patel, Shimman Arvind, Wei, Yongbin, Malladi, Durga Prasad
• Granted Patent: US 10,904,865 B2
• Time in Patent Office: Days
• CPC Class Codes: H04J 11/0023 Interference mitigation or co-ordination direct sequence spread spectrum [DSSS] systems H04B1/7097; frequency hopping H04B1/713; allocation criteria for ingress interference avoidance H04L5/0062; frequency allocation criteria for requirements on out-of-channel emissions H04L5/0066; arrangements for removing intersymbol interference or baseband equalisers H04L25/03006; peak power aspects in multicarrier modulation H04L27/2614; power management H04W52/00; traffic scheduling H04W72/54, H04W72/541
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04W 28/0278 using buffer status reports dynamic wireless traffic scheduling definition H04W72/12
• 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 74/002 Transmission of channel access control information
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/02 Hybrid access
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 74/0858 collision detection
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states

Abstract

Certain aspects relate to methods and apparatus for latency reduction for UEs in a RRC connected mode. During contention-based uplink access by groups of UEs within a subframe, an eNB may decode the received uplink transmission based, at least in part, on the assigned group of resources assigned to the UE and used for transmission. Additional orthogonalization techniques such as reduced TTI size can be used to reduce collisions among different users performing contention-based transmissions. Furthermore, when the eNB fails to successfully decode the uplink transmission, the eNB may identify the UE that sent the uplink transmission based on a detected reference signal and may transmit an uplink assignment to the identified UE.

Claims

1. A method for wireless communication by a user equipment (UE), comprising:

receiving an assignment assigning a group of resources within an uplink subframe to a group of UEs including the UE;

selecting, by the UE, resources from its assigned group of resources for contention-based access within the uplink subframe;

transmitting an uplink transmission in the subframe based to a base station (BS), at least in part, on the selected group of resources, wherein the uplink transmission includes a demodulated reference signal (DMRS);

receiving an uplink assignment in response to the uplink transmission; and

transmitting subsequent uplink transmissions using the uplink assignment.

2. The method of claim 1, wherein the assignment comprises a group of resources corresponding to a transmission time interval (TTI) with a duration that is less than a subframe.

3. The method of claim 2, wherein the TTI has a duration of less than one time slot of the subframe.

4. The method of claim 2, wherein the uplink transmission further comprises a buffer status report (BSR).

5. The method of claim 1, wherein the group of resources comprises different orthogonal codes assigned to each UE within the group of UEs.

6. The method of claim 1, wherein the group of resources comprises different cyclic shifts or root sequences assigned to each UE within the group of UEs.

7. The method of claim 1, wherein the UE comprises a machine-type communication (MTC) UE.

8. An apparatus for wireless communication by a user equipment (UE), comprising at least one processor and a memory coupled to the at least one processor, wherein the at least one processor is configured to:

receive an assignment assigning a group of resources within an uplink subframe to a group of UEs including the UE;

select, by the UE, resources from its assigned group of resources for contention-based access within the uplink subframe;

transmit an uplink transmission in the subframe based to a base station (BS), at least in part, on the selected group of resources, wherein the uplink transmission includes a demodulated reference signal (DMRS);

receive an uplink assignment in response to the uplink transmission; and

transmit subsequent uplink transmissions using the uplink assignment.

9. The apparatus of claim 8, wherein the assignment comprises a group of resources corresponding to a transmission time interval (TTI) with a duration that is less than a subframe.

10. The apparatus of claim 9, wherein the TTI has a duration of less than one time slot of the subframe.

11. The apparatus of claim 9, wherein the uplink transmission further comprises a buffer status report (BSR).

12. The apparatus of claim 8, wherein the group of resources comprises different orthogonal codes assigned to each UE within the group of UEs.

13. The apparatus of claim 8, wherein the group of resources comprises different cyclic shifts or root sequences assigned to each UE within the group of UEs.

14. The apparatus of claim 8, wherein the UE comprises a machine-type communication (MTC) UE.

15. An apparatus for wireless communication by a user equipment (UE), comprising:

means for receiving an assignment assigning a group of resources within an uplink subframe to a group of UEs including the UE;

means for selecting, by the UE, resources from its assigned group of resources for contention-based access within the uplink subframe;

means for transmitting an uplink transmissions in the subframe based to a base station (BS), at least in part, on the selected group of resources, wherein the uplink transmission includes a demodulated reference signal (DMRS);

means for receive an uplink assignment in response to the uplink transmission; and

means for transmitting subsequent uplink transmissions using the uplink assignment.

16. The apparatus of claim 15, wherein the assignment comprises a group of resources corresponding to a transmission time interval (TTI) with a duration that is less than a subframe.

17. The apparatus of claim 16, wherein the TTI has a duration of less than one time slot of the subframe.

18. The apparatus of claim 16, wherein the uplink transmission further comprises a buffer status report (BSR).

19. The apparatus of claim 15, wherein the group of resources comprises different orthogonal codes assigned to each UE within the group of UEs.

20. The apparatus of claim 15, wherein the group of resources comprises different cyclic shifts or root sequences assigned to each UE within the group of UEs.