SUPPORTING HIGH SPEEDS IN VEHICLE-TO-VEHICLE COMMUNICATION

• US 20170273128A1
• Filed: 11/30/2016
• Published: 09/21/2017
• Est. Priority Date: 03/21/2016
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: ABEDINI, Navid, JIANG, Libin, PATIL, Shailesh
• Granted Patent: US 11,251,893 B2
• Time in Patent Office: Days
• CPC Class Codes: H04J 13/0062 Zadoff-Chu
• CPC Class Codes: H04L 1/00 Arrangements for detecting or preventing errors in the information received correcting synchronisation H04L7/00
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0012 Hopping in multicarrier systems for frequency hopping in spread spectrum systems H04B1/713
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04L 5/0069 Allocation based on distance or geographical location allocation based on terminal or device properties in general, H04W72/51
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04W 4/021 Services related to particular areas, e.g. point of interest [POI] services, venue services or geofences
• CPC Class Codes: H04W 4/027 using movement velocity, acceleration information
• CPC Class Codes: H04W 4/46 for vehicle-to-vehicle communication [V2V]
• CPC Class Codes: H04W 4/50 Service provisioning or reconfiguring
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 72/51 based on terminal or device properties
• CPC Class Codes: H04W 76/14 Direct-mode setup

Abstract

During device-to-device communication between two devices, a communication transmitted from a first UE to a second UE may not be reliably received by the second UE if the first UE is traveling at high speed. Therefore, a travel speed of a transmitting UE may be considered in determining a transmission configuration. According to an aspect, the UE may determine a travel speed of the UE. The UE may determine, based on the travel speed of the UE, a transmission configuration of the UE for device-to-device communication. The UE may transmit the device-to-device communication based on the transmission configuration.

Claims

1. A method for wireless communication by a UE, comprising:

determining a travel speed of the UE;

determining, based on the travel speed of the UE, a transmission configuration of the UE for device-to-device communication; and

transmitting the device-to-device communication based on the transmission configuration.

2. The method of claim 1, wherein the transmission configuration includes at least one of a modulation and coding scheme (MCS), a number of resource blocks used for transmission, and a number of retransmissions.

3. The method of claim 2, wherein, when the travel speed of the UE increases, the determining comprises at least one of:

increasing a number of resource blocks used for transmission;

decreasing a modulation and coding scheme (MCS) value;

or

increasing a number of retransmissions.

4. The method of claim 2, wherein, when the travel speed of the UE decreases, the determining comprises at least one of:

decreasing a number of resource blocks used for transmission;

increasing a modulation and coding scheme (MCS) value;

or

decreasing a number of retransmissions.

5. The method of claim 1, wherein the travel speed of the UE is determined based on at least one of a travel speed of the UE or a maximum travel speed corresponding to a location of the UE.

6. The method of claim 5, wherein the maximum travel speed corresponding to the location of the UE is determined by:

determining the location of the UE; and

determining the maximum travel speed corresponding to the location of the UE.

7. The method of claim 5, wherein the maximum travel speed corresponding to the location of the UE is a speed limit of an area corresponding to the location of the UE.

8. The method of claim 5, wherein the travel speed of the UE is further determined based on a travel speed of a receiving UE.

9. The method of claim 1, wherein association information of the travel speed and a corresponding transmission configuration is preconfigured or is received from a base station.

10. The method of claim 1, wherein the transmitting of the device-to-device communication comprises:

transmitting a scheduling assignment (SA) based on an SA transmission configuration; and

transmitting data via a data channel based on a data transmission configuration.

11. The method of claim 10, wherein the SA indicates the data transmission configuration and a location of resources for the data channel.

12. The method of claim 10, wherein the transmitting of the device-to-device communication comprises:

transmitting the SA on any one of a plurality of sets of SA resources if the UE determines to utilize a fixed SA transmission configuration; and

transmitting the SA on a corresponding set of SA resources other than a first set of SA resources if the UE determines to vary the SA transmission configuration of the UE based on the travel speed of the UE,

wherein SA resources are divided into the plurality of sets of SA resources based on types of SA transmission configurations.

13. The method of claim 12, wherein the first set of SA resources is associated with the fixed SA transmission configuration, and

wherein each of other sets of SA resources is associated with a corresponding type of SA transmission configuration and the fixed SA transmission configuration.

14. The method of claim 12, wherein a size of each set of SA resources and at least one type of SA transmission configuration for each set of SA resources are associated with a corresponding travel speed of the UE.

15. The method of claim 14, wherein at least one of the size of each set of SA resources or the at least one type of SA transmission configuration for each set of SA resources is preconfigured or is received from a base station.

16. A method for wireless communication by a UE, comprising:

receiving a communication from a transmitting UE via device-to-device communication;

determining a corresponding set of scheduling assignment (SA) resources used to receive the communication from the transmitting UE among a plurality of sets of SA resources, wherein SA resources are divided into the plurality of sets of SA resources based on types of SA transmission configurations;

decoding an SA based on the communication within the corresponding set of SA resources;

determining a data transmission configuration based on the SA within the corresponding set of SA resources; and

receiving data from the transmitting UE based on the data transmission configuration.

17. The method of claim 16, wherein the decoding the SA comprises:

performing blind decoding within the corresponding set of SA resources to decode the SA indicating the data transmission configuration.

18. The method of claim 16, wherein the decoding the SA comprises:

decoding for an SA based on a fixed SA configuration if the corresponding set of SA resources is a first set of SA resources; and

decoding for an SA based on the fixed SA configuration or an SA based on an SA transmission configuration corresponding to the corresponding set of SA resources if the corresponding set of SA resources is a set of SA resources different from the first set of SA resources.

19. The method of claim 16, wherein the data transmission configuration includes at least one of a modulation and coding scheme (MCS), a number of resource blocks used for transmission, and a number of retransmissions.

20. The method of claim 16, wherein the receiving the data comprises:

determining a location of resources for a data channel based on the SA; and

receiving the data based on the location of resources for the data channel and the data transmission configuration.

21. The method of claim 16, wherein a size of each set of SA resources and at least one type of SA transmission configuration for each set of SA resources is associated with a corresponding travel speed of the transmitting UE.

22. The method of claim 21, wherein at least one of the size of each set of SA resources or the at least one type of SA transmission configuration for each set of SA resources is preconfigured or is received from a base station.

23. A UE for wireless communication, comprising:

means for determining a travel speed of the UE;

means for determining, based on the travel speed of the UE, a transmission configuration of the UE for device-to-device communication; and

means for transmitting the device-to-device communication based on the transmission configuration.

24. The UE of claim 23, wherein the transmission configuration includes at least one of a modulation and coding scheme (MCS), a number of resource blocks used for transmission, and a number of retransmissions.

25. The UE of claim 24, wherein, when the travel speed of the UE increases, the means for determining is configured to perform at least one of:

increasing a number of resource blocks used for transmission;

decreasing a modulation and coding scheme (MCS) value;

or

increasing a number of retransmissions.

26. The UE of claim 24, wherein, when the travel speed of the UE decreases, the means for determining is configured to perform at least one of:

decreasing a number of resource blocks used for transmission;

increasing a modulation and coding scheme (MCS) value;

or

decreasing a number of retransmissions.

27. The UE of claim 23, wherein the travel speed is determined based on at least one of a travel speed of the UE or a maximum travel speed corresponding to a location of the UE.

28. The UE of claim 27, wherein the maximum travel speed corresponding to the location of the UE is determined by:

determining the location of the UE; and

determining the maximum travel speed corresponding to the location of the UE.

29. The UE of claim 27, wherein the maximum travel speed corresponding to the location of the UE is a speed limit of an area corresponding to the location of the UE.

30. The UE of claim 27, wherein travel speed is further determined based on a travel speed of a receiving UE.

31. The UE of claim 23, wherein association information of the travel speed and a corresponding transmission configuration is preconfigured or is received from a base station.

32. The UE of claim 23, wherein the means for transmitting of the device-to-device communication is configured to:

transmit a scheduling assignment (SA) based on an SA transmission configuration; and

transmit data via a data channel based on a data transmission configuration.

33. The UE of claim 32, wherein the SA indicates the data transmission configuration and a location of resources for the data channel.

34. The UE of claim 32, wherein the means for transmitting the device-to-device communication is configured to:

transmit the SA on any one of a plurality of sets of SA resources if the UE determines to utilize a fixed SA transmission configuration; and

transmit the SA on a corresponding set of SA resources other than a first set of SA resources if the UE determines to vary the SA transmission configuration of the UE based on the travel speed of the UE,

wherein SA resources are divided into the plurality of sets of SA resources based on types of SA transmission configurations.

35. The UE of claim 34, wherein the first set of SA resources is associated with the fixed SA transmission configuration, and

wherein each of other sets of SA resources is associated with a corresponding type of SA transmission configuration and the fixed SA transmission configuration.

36. The UE of claim 34, wherein a size of each set of SA resources and at least one type of SA transmission configuration for each set of SA resources are associated with a corresponding travel speed of the UE.

37. The UE of claim 36, wherein at least one of the size of each set of SA resources or the at least one type of SA transmission configuration for each set of SA resources is preconfigured or is received from a base station.

38. A UE for wireless communication by a UE, comprising:

means for receiving communication from a transmitting UE via device-to-device communication;

means for determining a corresponding set of scheduling assignment (SA) resources used to receive the communication from the transmitting UE among a plurality of sets of SA resources, wherein SA resources are divided into the plurality of sets of SA resources based on types of SA transmission configurations;

means for decoding an SA based on the communication within the corresponding set of SA resources;

means for determining a data transmission configuration based on the SA within the corresponding set of SA resources; and

means for receiving data from the transmitting UE based on the data transmission configuration.

39. The UE of claim 38, wherein the means for decoding the SA is configured to:

perform blind decoding within the corresponding set of SA resources to decode the SA indicating the data transmission configuration.

40. The UE of claim 38, wherein the means for decoding the SA is configured to:

decode for an SA based on a fixed SA configuration if the corresponding set of SA resources is a first set of SA resources; and

decode for an SA based on the fixed SA configuration or an SA based on an SA transmission configuration corresponding to the corresponding set of SA resources if the corresponding set of SA resources is a set of SA resources different from the first set of SA resources.

41. The UE of claim 38, wherein the data transmission configuration includes at least one of a modulation and coding scheme (MCS), a number of resource blocks used for transmission, and a number of retransmissions.

42. The UE of claim 38, wherein the means for receiving the data is configured to:

determine a location of resources for a data channel based on the SA; and

receive the data based on the location of resources for the data channel and the data transmission configuration.

43. The UE of claim 38, wherein a size of each set of SA resources and at least one type of SA transmission configuration for each set of SA resources is associated with a corresponding travel speed of the transmitting UE.

44. The UE of claim 43, wherein at least one of the size of each set of SA resources or the at least one type of SA transmission configuration for each set of SA resources is preconfigured or is received from a base station.

45. A UE for wireless communication, comprising:

a memory; and

at least one processor coupled to the memory and configured to;

determine a travel speed of the UE;

determine, based on the travel speed of the UE, a transmission configuration of the UE for device-to-device communication; and

transmit the device-to-device communication based on the transmission configuration.

46. The UE of claim 45, wherein the transmission configuration includes at least one of a modulation and coding scheme (MCS), a number of resource blocks used for transmission, and a number of retransmissions.

47. The UE of claim 46, wherein, when the travel speed of the UE increases, the at least one processor configured to set the transmission configuration is configured to perform at least one of:

increasing a number of resource blocks used for transmission;

decreasing a modulation and coding scheme (MCS) value;

or

increasing a number of retransmissions.

48. The UE of claim 46, wherein, when the travel speed of the UE decreases, to determine the transmission configuration, the at least one processor is configured to perform at least one of:

decreasing a number of resource blocks used for transmission;

increasing a modulation and coding scheme (MCS) value;

or

decreasing a number of retransmissions.

49. The UE of claim 45, wherein the travel speed is determined based on at least one of a travel speed of the UE or a maximum travel speed corresponding to a location of the UE.

50. The UE of claim 49, wherein the maximum travel speed corresponding to the location of the UE is determined by:

determining the location of the UE; and

determining the maximum travel speed corresponding to the location of the UE.

51. The UE of claim 49, wherein the maximum travel speed corresponding to the location of the UE is a speed limit of an area corresponding to the location of the UE.

52. The UE of claim 49, wherein travel speed is further determined based on a travel speed of a receiving UE.

53. The UE of claim 45, wherein association information of the travel speed and a corresponding transmission configuration is preconfigured or is received from a base station.

54. The UE of claim 45, wherein the at least one processor configured to transmit the device-to-device communication is configured to:

transmit a scheduling assignment (SA) based on an SA transmission configuration; and

transmit data via a data channel based on a data transmission configuration.

55. The UE of claim 54, wherein the SA indicates the data transmission configuration and a location of resources for the data channel.

56. The UE of claim 54, wherein the at least one processor configured to transmit the device-to-device communication is configured to:

transmit the SA on any one of a plurality of sets of SA resources if the UE determines to utilize a fixed SA transmission configuration; and

transmit the SA on a corresponding set of SA resources other than a first set of SA resources if the UE determines to vary the SA transmission configuration of the UE based on the travel speed of the UE,

wherein SA resources are divided into the plurality of sets of SA resources based on types of SA transmission configurations.

57. The UE of claim 56, wherein the first set of SA resources is associated with the fixed SA transmission configuration, and

wherein each of other sets of SA resources is associated with a corresponding type of SA transmission configuration and the fixed SA transmission configuration.

58. The UE of claim 56, wherein a size of each set of SA resources and at least one type of SA transmission configuration for each set of SA resources are associated with a corresponding travel speed of the UE.

59. The UE of claim 58, wherein at least one of the size of each set of SA resources or the at least one type of SA transmission configuration for each set of SA resources is preconfigured or is received from a base station.

60. A UE for wireless communication by a UE, comprising:

a memory; and

at least one processor coupled to the memory and configured to;

receive a communication from a transmitting UE via device-to-device communication;

determine a corresponding set of scheduling assignment (SA) resources used to receive the communication from the transmitting UE among a plurality of sets of SA resources, wherein SA resources are divided into the plurality of sets of SA resources based on types of SA transmission configurations;

decode an SA based on the communication within the corresponding set of SA resources;

determine a data transmission configuration based on the SA within the corresponding set of SA resources; and

receive data from the transmitting UE based on the data transmission configuration.

61. The UE of claim 60, wherein the at least one processor to decode the SA is configured to:

perform blind decoding within the corresponding set of SA resources to decode the SA indicating the data transmission configuration.

62. The UE of claim 60, wherein the at least one processor to decode the SA is configured to:

decode for an SA based on a fixed SA configuration if the corresponding set of SA resources is a first set of SA resources; and

decode for an SA based on the fixed SA configuration or an SA based on an SA transmission configuration corresponding to the corresponding set of SA resources if the corresponding set of SA resources is a set of SA resources different from the first set of SA resources.

63. The UE of claim 60, wherein the data transmission configuration includes at least one of a modulation and coding scheme (MCS), a number of resource blocks used for transmission, and a number of retransmissions.

64. The UE of claim 60, wherein the at least one processor to receive the data is configured to:

determine a location of resources for a data channel based on the SA; and

receive the data based on the location of resources for the data channel and the data transmission configuration.

65. The UE of claim 60, wherein a size of each set of SA resources and at least one type of SA transmission configuration for each set of SA resources is associated with a corresponding travel speed of the transmitting UE.

66. The UE of claim 65, wherein at least one of the size of each set of SA resources or the at least one type of SA transmission configuration for each set of SA resources is preconfigured or is received from a base station.

67. A computer-readable medium for a UE storing computer executable code, comprising code to:

determine a travel speed of the UE;

determine, based on the travel speed of the UE, a transmission configuration of the UE for device-to-device communication; and

transmit the device-to-device communication based on the transmission configuration.

68. A computer-readable medium for a UE storing computer executable code, comprising code to:

receive communication from a transmitting UE via device-to-device communication;

determine a corresponding set of scheduling assignment (SA) resources used to receive the communication from the transmitting UE among a plurality of sets of SA resources, wherein SA resources are divided into the plurality of sets of SA resources based on types of SA transmission configurations;

decode an SA based on the communication within the corresponding set of SA resources;

determine a data transmission configuration based on the SA within the corresponding set of SA resources; and

receive data from the transmitting UE based on the data transmission configuration.

69. A method for wireless communication by a UE, comprising:

determining to enable group hopping for a plurality of demodulation reference signal (DM-RS) sequences associated with a control channel for device-to-device communication, the plurality of DM-RS sequences being carried on a plurality of DM-RS symbols within the control channel of a subframe;

determining the plurality of DM-RS sequences by applying a group hopping pattern to the plurality of DM-RS symbols; and

transmitting or receiving scheduling assignment for the device-to-device communication with the plurality of DM-RS sequences.

70. The method of claim 69, wherein the determining to enable group hopping is based on one or more of a travel speed of the UE, a pre-configuration, or an eNB signaling.

71. The method of claim 69, wherein different DM-RS sequences are carried on different DM-RS symbols.

72. The method of claim 69, wherein the plurality of DM-RS sequences are based on Zadoff-Chu sequences.

73. The method of claim 72, wherein the applying of the group hopping pattern to the plurality of DM-RS symbols comprises changing root indices of the Zadoff-Chu sequences used for different DM-RS symbols.

74. The method of claim 73, wherein a root index of a Zadoff-Chu sequence used for a DM-RS symbol of the plurality of DM-RS symbols is determined based on a time resource index.

75. The method of claim 74, wherein the time resource index is one of a slot index of the DM-RS symbol or a symbol index of the DM-RS symbol.

76. The method of claim 74, wherein the root index of the Zadoff-Chu sequence used for the DM-RS symbol is determined further based on a frequency resource index used by the control channel.

77. The method of claim 74, wherein the root index of the Zadoff-Chu sequence used for the DM-RS symbol is determined further based on an identifier.

78. The method of claim 77, wherein the identifier is determined based at least in part on a scheduling assignment identifier associated with the device-to-device communication.

79. The method of claim 77, wherein the identifier is a fixed identifier.

80. The method of claim 69, further comprising;

determining a second plurality of DM-RS sequences associated with a data channel for the device-to-device communication by applying a second group hopping pattern to a second plurality of DM-RS symbols within the data channel of the subframe; and

transmitting or receiving data for the device-to-device communication with the second plurality of DM-RS sequences.

81. The method of claim 80, wherein the second plurality of DM-RS sequences are based on Zadoff-Chu sequences.

82. The method of claim 81, wherein the applying of the second group hopping pattern to the second plurality of DM-RS symbols comprises changing root indices of the Zadoff-Chu sequences used for different DM-RS symbols.

83. The method of claim 82, wherein a root index of a Zadoff-Chu sequence used for a DM-RS symbol of the second plurality of DM-RS symbols is determined based on a slot index of the DM-RS symbol.

84. An apparatus for wireless communication, comprising:

means for determining to enable group hopping for a plurality of demodulation reference signal (DM-RS) sequences associated with a control channel for device-to-device communication, the plurality of DM-RS sequences being carried on a plurality of DM-RS symbols within the control channel of a subframe;

means for determining the plurality of DM-RS sequences by applying a group hopping pattern to the plurality of DM-RS symbols; and

means for transmitting or receiving a scheduling assignment for the device-to-device communication with the plurality of DM-RS sequences.

85. The apparatus of claim 84, wherein the means for determining to enable group hopping is configured to operate based on one or more of a travel speed of the apparatus, a pre-configuration, or an eNB signaling.

86. The apparatus of claim 84, wherein different DM-RS sequences are carried on different DM-RS symbols.

87. The apparatus of claim 84, wherein the plurality of DM-RS sequences are based on Zadoff-Chu sequences.

88. The apparatus of claim 87, wherein, to apply the group hopping pattern to the plurality of DM-RS symbols, the means for determining the plurality of DM-RS sequences is configured to change root indices of the Zadoff-Chu sequences used for different DM-RS symbols.

89. The apparatus of claim 88, wherein a root index of a Zadoff-Chu sequence used for a DM-RS symbol of the plurality of DM-RS symbols is determined based on a time resource index.

90. The apparatus of claim 89, wherein the time resource index is one of a slot index of the DM-RS symbol or a symbol index of the DM-RS symbol.

91. The apparatus of claim 89, wherein the root index of the Zadoff-Chu sequence used for the DM-RS symbol is determined further based on a frequency resource index used by the control channel.

92. The apparatus of claim 89, wherein the root index of the Zadoff-Chu sequence used for the DM-RS symbol is determined further based on an identifier.

93. The apparatus of claim 92, wherein the identifier is determined based at least in part on a scheduling assignment identifier associated with the device-to-device communication.

94. The apparatus of claim 92, wherein the identifier is a fixed identifier.

95. The apparatus of claim 84, further comprising;

means for determining a second plurality of DM-RS sequences associated with a data channel for the device-to-device communication by applying a second group hopping pattern to a second plurality of DM-RS symbols within the data channel of the subframe; and

means for transmitting or receiving data for the device-to-device communication with the second plurality of DM-RS sequences.

96. The apparatus of claim 95, wherein the second plurality of DM-RS sequences are based on Zadoff-Chu sequences.

97. The apparatus of claim 96, wherein, to apply the second group hopping pattern to the second plurality of DM-RS symbols, the means for determining the second plurality of DM-RS sequences is configured to change root indices of the Zadoff-Chu sequences used for different DM-RS symbols.

98. The apparatus of claim 97, wherein a root index of a Zadoff-Chu sequence used for a DM-RS symbol of the second plurality of DM-RS symbols is determined based on a slot index of the DM-RS symbol.

99. An apparatus for wireless communication, comprising:

a memory; and

at least one processor coupled to the memory and configured to;

determine to enable group hopping for a plurality of demodulation reference signal (DM-RS) sequences associated with a control channel for device-to-device communication, the plurality of DM-RS sequences being carried on a plurality of DM-RS symbols within the control channel of a subframe;

determine the plurality of DM-RS sequences by applying a group hopping pattern to the plurality of DM-RS symbols; and

transmit or receive scheduling assignment for the device-to-device communication with the plurality of DM-RS sequences.

100. The apparatus of claim 99, wherein, to determine to enable group hopping, the at least one processor is configured to operate based on one or more of a travel speed of the apparatus, a pre-configuration, or an eNB signaling.

101. The apparatus of claim 99, wherein different DM-RS sequences are carried on different DM-RS symbols.

102. The apparatus of claim 99, wherein the plurality of DM-RS sequences are based on Zadoff-Chu sequences.

103. The apparatus of claim 102, wherein, to apply the group hopping pattern to the plurality of DM-RS symbols comprises, the at least one processor is configured to change root indices of the Zadoff-Chu sequences used for different DM-RS symbols.

104. The apparatus of claim 103, wherein a root index of a Zadoff-Chu sequence used for a DM-RS symbol of the plurality of DM-RS symbols is determined based on a time resource index.

105. The apparatus of claim 104, wherein the time resource index is one of a slot index of the DM-RS symbol or a symbol index of the DM-RS symbol.

106. The apparatus of claim 104, wherein the root index of the Zadoff-Chu sequence used for the DM-RS symbol is determined further based on a frequency resource index used by the control channel.

107. The apparatus of claim 104, wherein the root index of the Zadoff-Chu sequence used for the DM-RS symbol is determined further based on an identifier.

108. The apparatus of claim 107, wherein the identifier is determined based at least in part on a scheduling assignment identifier associated with the device-to-device communication.

109. The apparatus of claim 107, wherein the identifier is a fixed identifier.

110. The apparatus of claim 99, wherein the at least one processor is further configured to;

determine a second plurality of DM-RS sequences associated with a data channel for the device-to-device communication by applying a second group hopping pattern to a second plurality of DM-RS symbols within the data channel of the subframe; and

transmit or receive data for the device-to-device communication with the second plurality of DM-RS sequences.

111. The apparatus of claim 110, wherein the second plurality of DM-RS sequences are based on Zadoff-Chu sequences.

112. The apparatus of claim 111, wherein, to apply the second group hopping pattern to the second plurality of DM-RS symbols, the at least one processor is configured to change root indices of the Zadoff-Chu sequences used for different DM-RS symbols.

113. The apparatus of claim 112, wherein a root index of a Zadoff-Chu sequence used for a DM-RS symbol of the second plurality of DM-RS symbols is determined based on a slot index of the DM-RS symbol.

114. A computer-readable medium for a UE storing computer executable code, comprising code to:

determine to enable group hopping for a plurality of demodulation reference signal (DM-RS) sequences associated with a control channel for device-to-device communication, the plurality of DM-RS sequences being carried on a plurality of DM-RS symbols within the control channel of a subframe;

determine the plurality of DM-RS sequences by applying a group hopping pattern to the plurality of DM-RS symbols; and

transmit or receive scheduling assignment for the device-to-device communication with the plurality of DM-RS sequences.