Transmission and reception timing for device-to-device communication system embedded in a cellular system

An apparatus for wireless communication in a cellular communication system, the apparatus being a user equipment (UE) and comprising:

• means for identifying a propagated start point of a first portion of at least one time-frequency resource, wherein the propagated start point is based on a network start point of the first portion and one of a propagation delay or a propagation advance between the UE and a base station;
• and
• means for transmitting a device-to-device (D2D) signal beginning from a transmission start point and ending at a transmission end point, the transmission start point being based on the propagated start point and addition of a timing offset to the propagated start point, the timing offset being based on a propagation delay between the UE and the base station when the at least one time-frequency resource is embedded in downlink resources of the base station, the transmission end point being based on subtraction of a timing advance from a propagated end point, the timing advance based on a propagation delay between the UE and a second UE, the addition of the timing offset causing the transmission of the D2D signal to start after the propagated start point and the subtraction of the timing advance causing the transmission of the D2D signal to end before the propagated end point, wherein a number of D2D symbols n transmitted on the at least one time-frequency resource to be used for D2D communication is provided by the following equation:
• n=└(G−X−Y)/SL┘,
• wherein G is a difference between an allocated D2D resource end point and an allocated D2D resource start point, X is the timing offset, Y is a D2D timing advance, and SL is a symbol length.

An apparatus for wireless communication in a cellular communication system, the apparatus being a user equipment (UE) and comprising:

• a memory;
• and
• at least one processor coupled to the memory and configured to:
• identify a propagated start point of a first portion of at least one time-frequency resource, wherein the propagated start point is based on a network start point of the first portion and one of a propagation delay or a propagation advance between the UE and a base station;
• and
• transmit a device-to-device (D2D) signal beginning from a transmission start point and ending at a transmission end point, the transmission start point being based on the propagated start point and addition of a timing offset to the propagated start point, the timing offset being based on a propagation delay between the UE and the base station when the at least one time-frequency resource is embedded in downlink resources of the base station, the transmission end point being based on subtraction of a timing advance from a propagated end point, the timing advance based on a propagation delay between the UE and a second UE, the addition of the timing offset causing the transmission of the D2D signal to start after the propagated start point and the subtraction of the timing advance causing the transmission of the D2D signal to end before the propagated end point, wherein a number of D2D symbols n transmitted on the at least one time-frequency resource to be used for D2D communication is provided by the following equation:
• n=└(G−X−Y)/SL┘,
• wherein G is a difference between an allocated D2D resource end point and an allocated D2D resource start point, X is the timing offset, Y is a D2D timing advance, and SL is a symbol length.

A non-transitory computer-readable medium storing computer executable code for communication in a cellular communication system, comprising code to:

• identify, by a user equipment (UE), a propagated start point of a first portion of at least one time-frequency resource, wherein the propagated start point is based on a network start point of the first portion and one of a propagation delay or a propagation advance between the UE and a base station;
• and
• transmit, by the UE, a device-to-device (D2D) signal beginning from a transmission start point and ending at a transmission end point, the transmission start point being based on the propagated start point and addition of a timing offset to the propagated start point, the timing offset being based on a propagation delay between the UE and the base station when the at least one time-frequency resource is embedded in downlink resources of the base station, the transmission end point being based on subtraction of a timing advance from a propagated end point, the timing advance based on a propagation delay between the UE and a second UE, the addition of the timing offset causing the transmission of the D2D signal to start after the propagated start point and the subtraction of the timing advance causing the transmission of the D2D signal to end before the propagated end point, wherein a number of D2D symbols n transmitted on the at least one time-frequency resource to be used for D2D communication is provided by the following equation:
• n=└(G−X−Y)/SL┘,
• wherein G is a difference between an allocated D2D resource end point and an allocated D2D resource start point, X is the timing offset, Y is a D2D timing advance, and SL is a symbol length.