Communication system, communication device, base station and method thereof for d2d communications

A method for transmitting a plurality of data packets in a wireless network, used in a communication device, comprising:

• receiving one or more first medium access control (MAC) protocol data units (PDUs) which include a plurality of radio link control (RLC) PDUs intended for a destination user equipment (UE) from a source UE of the wireless network;
• demultiplexing the first MAC PDUs to retrieve the RLC PDUs based on a header field of each first MAC PDU;
• generating a plurality of RLC PDU segments from one or more of the RLC PDUs or a plurality of RRLC (Relay RLC) PDUs from all of the RLC PDUs according to one or more MAC PDU sizes, wherein the RRLC is a protocol layer between the MAC layer and the RLC layer;
• multiplexing the RLC PDUs and the RLC PDU segments or the RRLC PDUs into one or more second MAC PDUs;
• and
• transmitting the second MAC PDUs to the destination UE.

A communication device for receiving a plurality of data packets in a wireless network, at least comprising:

• a control circuit;
• a processor installed in the control circuit;
• a memory installed in the control circuit and coupled to the processor;
• wherein the processor is configured to execute a program code stored in memory to:
• receive one or more medium access control (MAC) protocol data units (PDUs) from a source user equipment (UE) of the wireless network through a relay UE, a base station and directly from the source UE, wherein the MAC PDUs are composed of a plurality of radio link control (RLC) PDUs and a plurality of RLC PDU segments;
• demultiplex the MAC PDUs to retrieve the RLC PDUs and the RLC PDU segments based on a header field of each MAC PDU;
• reorder the RLC PDUs and the RLC PDU segments and perform a duplicate detection of the RLC PDUs and the RLC PDU segments according to transmission sequence numbers (TSNs), wherein each TSN is included in a header field of each RLC PDU and each RLC PDU segment;
• and
• reassemble the RLC PDUs and the RLC PDU segments into a plurality of RLC service data units (SDUs) using information included in the header field of each RLC PDU and each RLC PDU segment.

A communication device for receiving a plurality of data packets in a wireless network, at least comprising:

• a control circuit;
• a processor installed in the control circuit;
• a memory installed in the control circuit and coupled to the processor;
• wherein the processor is configured to execute a program code stored in memory to:
• receive a plurality of first medium access control (MAC) protocol data units (PDUs) from a source user equipment (UE) of the wireless network through a relay UE and a base station, wherein the first MAC PDUs are composed of a plurality of RRLC (Relay RLC) PDUs which are protocol data units of a protocol layer between the MAC layer and the RLC layer, and receiving a plurality of second MAC PDUs from the source UE directly, wherein the second MAC PDUs are composed of a plurality of first RLC PDUs and a plurality of first RLC PDU segments;
• demultiplex the first MAC PDUs to retrieve the RRLC PDUs based on a header field of each first MAC PDU, and demultiplex the second MAC PDUs to retrieve the first RLC PDUs and the first RLC PDU segments based on a header field of each second MAC PDU;
• reorder the RRLC PDUs and perform a duplicate detection of the RRLC PDUs according to transmission sequence numbers (TSNs), wherein each TSN is included in a header field of each RRLC PDU;
• reassemble the RRLC PDUs into a plurality of second RLC PDUs and a plurality of second RLC PDU segments using information included in the header field of each RRLC PDU;
• reorder the first RLC PDUs, the first RLC PDU segments, the second RLC PDUs, and the second RLC PDU segments, and perform a duplicate detection of the first RLC PDUs, the first RLC PDU segments, the second RLC PDUs, and the second RLC PDU segments according to the TSNs, wherein each TSN is included in a header field of each RLC PDU and each RLC PDU segment;
• and
• reassemble the first RLC PDUs, the first RLC PDU segments, the second RLC PDUs, and the second RLC PDU segments into a plurality of RLC service data units (SDUs) using the information included in the header field of each RLC PDU and each RLC PDU segment.

A method for receiving a plurality of data packets in a wireless network, used in a communication device, comprising:

• receiving one or more medium access control (MAC) protocol data units (PDUs) from a source user equipment (UE) of the wireless network through a relay UE, a base station and directly from the source UE, wherein the MAC PDUs are composed of a plurality of radio link control (RLC) PDUs and a plurality of RLC PDU segments;
• demultiplexing the MAC PDUs to retrieve the RLC PDUs and the RLC PDU segments based on a header field of each MAC PDU;
• reordering the RLC PDUs and the RLC PDU segments and performing a duplicate detection of the RLC PDUs and the RLC PDU segments according to transmission sequence numbers (TSNs), wherein each TSN is included in a header field of each RLC PDU and each RLC PDU segment;
• and
• reassembling the RLC PDUs and the RLC PDU segments into a plurality of RLC service data units (SDUs) using information included in the header field of each RLC PDU and each RLC PDU segment.

A method for receiving a plurality of data packets in a wireless network, used in a communication device, comprising:

• receiving a plurality of first medium access control (MAC) protocol data units (PDUs) from a source user equipment (UE) of the wireless network through a relay UE and a base station, wherein the first MAC PDUs are composed of a plurality of RRLC (Relay RLC) PDUs which are protocol data units of a protocol layer between the MAC layer and the RLC layer, and receiving a plurality of second MAC PDUs from the source UE directly, wherein the second MAC PDUs are composed of a plurality of first RLC PDUs and a plurality of first RLC PDU segments;
• demultiplexing the first MAC PDUs to retrieve the RRLC PDUs based on a header field of each first MAC PDU, and demultiplexing the second MAC PDUs to retrieve the first RLC PDUs and the first RLC PDU segments based on a header field of each second MAC PDU;
• reordering the RRLC PDUs and performs a duplicate detection of the RRLC PDUs according to transmission sequence numbers (TSNs), wherein each TSN is included in a header field of each RRLC PDU;
• reassembling the RRLC PDUs into a plurality of second RLC PDUs and a plurality of second RLC PDU segments using information included in the header field of each RRLC PDU;
• reordering the first RLC PDUs, the first RLC PDU segments, the second RLC PDUs, and the second RLC PDU segments, and performing a duplicate detection of the first RLC PDUs, the first RLC PDU segments, the second RLC PDUs, and the second RLC PDU segments according to the TSNs, wherein each TSN is included in a header field of each RLC PDU and each RLC PDU segment;
• and
• reassembling the first RLC PDUs, the first RLC PDU segments, the second RLC PDUs, and the second RLC PDU segments into a plurality of RLC service data units (SDUs) using the information included in the header field of each RLC PDU and each RLC PDU segment.

A method for allocating resources for Device-to-Device (D2D) communications of a plurality of user equipments (UEs), used in a base station, the method comprising:

• receiving channel state information (CSI) reported by the UEs;
• estimating link qualities of all D2D communication pairs according to the CSI;
• determining a suitable D2D communication mode for each D2D communication pair according to the link qualities;
• and
• allocating physical resource blocks (PRBs) according to the link qualities.

A communication system for D2D communications in a wireless network, at least comprising:

• a source user equipment (UE);
• a destination UE;
• a relay UE;
• and
• a base station, receiving channel state information (CSI) reported by the source UE, the destination UE, and the relay UE;
• wherein the base station estimates link qualities of all D2D communication pairs according to the CSI, and determines a suitable D2D communication mode from the source UE to the destination UE according to the link qualities, and transmits a resource grant to the source UE to instruct the source UE to transmit data packets to the destination UE in the suitable D2D communication mode;
• wherein the suitable D2D communication mode is a connection set between the source UE and the destination UE, between the source UE and the destination UE through the relay UE, or between the source UE and the destination UE through the base station.