Method for Transmitting Packets in Relay Networks

• US 20100128651A1
• Filed: 11/26/2008
• Published: 05/27/2010
• Est. Priority Date: 11/26/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Zhang, Jinyun, Molisch, Andreas F., Yim, Raymond
• Granted Patent: US 8,243,649 B2
• Time in Patent Office: Days
• US Class Current: 370/315
• CPC Class Codes: H04B 7/15592 Adapting at the relay station communication parameters for supporting cooperative relaying, i.e. transmission of the same data via direct - and relayed path cooperative diversity H04B7/024

Abstract

A method transmits an L bit packet in a relay network including a source node, a relay node and a destination node. The source node partitions the packet into first fragment of βL bits and a second fragment of (1−β) bits. The first fragment is transmitted from the source node to the relay node at a first data rate during a first phase. The second fragment is transmitted from the source node to the destination node at a second data rate during a second phase while the first fragment is retransmitted from the relay node to the destination node at a third data rate.

Claims

1. A method for transmitting a packet in a relay network including a source node, a relay node and a destination node, comprising:

partitioning, in a source node of a relay network, a packet into a first fragment and a second fragment, wherein the packet has L bits and the first fragment has β

L and the second fragment has (1−

β

)L bits, where β

is a splitting ratio;

transmitting the first fragment from the source node to a relay node of the relay network at a first data rate during a first phase;

transmitting the second fragment from the source node to a destination node in the relay network at a second data rate during a second phase;

retransmitting the first fragment from the relay node to the destination node at a third data rate during the second phase; and

optimizing the first, second and third data rates so that a total energy consumption in the network is minimized.

2. The method of claim 1, further comprising:

combining the first fragments and the second fragment in the destination node.

3. The method of claim 1, further comprising:

retransmitting a fraction of the first fragment from the source node to the destination node at the second data rate during the second phase.

4. The method of claim 3, wherein the retransmitting of the fraction of the first fragment uses Slepian-Wolf coding.

5. The method of claim 1, wherein P₀ is a power used by the source node during the first phase, p_s is the power used by the source during the second phase, and p_r is the power used by the relay node during the second phase.

6. The method of claim 2, wherein P₀ is a power used by the source node during the first phase, p_s is the power used by the source during the second phase, and p_r is the power used by the relay node during the second phase and wherein a power gain between the source node s and the relay node r is |h_sr|², and the power gain between the relay node s and the destination node d is |h_rd|², and the combining is according to h_sd and h_rd.

7. The method of claim 6, wherein the second data rate R_sd from the source to the destination satisfies R_sd≦

C(|h_sd|²P_s), where

8. The method claim 7, in which the transmitting of the second fragment and the retransmitting of the first fragment use multiple-packet reception (mpr), and packets are received successfully if and only if the second data rate R_sd-mpr and the third data rate R_rd-mpr, satisfy an information theoretic bounds for a multiple access channel according to

9. The method of claim 1, wherein a transmission delay and a retransmission delay during the second phase are equal.

10. The method of claim 6, wherein the energy consumption is minimized according to

11. The method of claim 7, wherein bounds on the split ratio β

are

12. The method of claim 11, further comprising:

selecting the powers P₀, P_s and P_r, as a function of |h_sr|², |h_rd|², |h_sd|², and an objective overall transmission data rate R optimizes;

13. The method of claim 1, wherein the first and second segments are respectively transmitted and retransmitted concurrently during the second phase.

14. The method of claim 1, wherein the second and third data rates are different.

15. The method of claim 1, wherein all nodes have a single antenna, one transceiver radio frequency chain.

16. The method of claim 1, wherein the nodes use the same frequency band.