Source Destination Cooperation

Project Description:

In this project, we consider the relay channel, multiple access channel (MAC) and interference channel (IC), and apply different cooperative techniques between the sources and/or the destinations of these channels. All of these cooperative techniques can be applied to uplink cellular communication as shown in Figure 1.

For the relay channel, we consider relay destination cooperation (RDC) in which the destination (base station) cooperates in order to increase transmission rates. We apply a similar idea to the MAC by considering this channel with source and destination cooperation (SDC). We engage the destination in cooperation because in cellular networks, the base station is more powerful and has more capabilities than the mobiles. For the IC, we consider cooperation between base stations, which is possible via the backhaul network connecting them.

Figure 1. Models for the Relay Channel with RDC, Multiple-access channel with SDC and the interference channel with DC.
Figure 1. Models for the Relay Channel with RDC, Multiple-access channel with SDC and the interference channel with DC.

Since the MAC-SDC includes the relay channel with RDC as a special case, we present the cooperative channel in the following order: MAC-SDC, relay channel with RDC, and then the IC-DC.

 

Multiple access channel with joint source-destination cooperation (MAC-SDC):

In this project, we aim to understand the impact of joint source destination cooperation (SDC) on the achievable rate region of a multi-user channel. We consider the uplink communication shown in Figure 1. In cellular networks, the base station is more powerful and has more capabilities than the mobile stations. Hence, in uplink communication, destination cooperation may improve the achievable rates in addition to the source cooperation. We want to understand how and when it is beneficial to use SDC.

 

Transmission scheme:

EDMACSD
Figure 2

We propose a coding scheme as shown in Figure 2. Each source employs superposition block Markov encoding and partial decode-forward relaying, while the destination employs quantize-forward relaying and backward decoding. The sources partially exchange their messages using not only the direct links between them as in source cooperation, but also the feedback links from the destination. Hence, the sources are able to exchange more information using the same amount of power by utilizing the destination as a relay.

 

 

Achievable rate region

Figure 3
Figure 3

Figure 3 compares between the achievable rate regions of the proposed scheme (JSDC), the source cooperation scheme, the non-cooperative classical multiple access channel (MAC), and the cut set bound. Results show that JSDC can significantly improve the achievable rate region, especially when the cooperative link qualities are close to source-destination link qualities.

 

 

 

 

 

 

Efficient use in Cellular Networks

Figure 4
Figure 4

Figure 4 demonstrates that JSDC is more attractive when the cooperative links are close to the direct links. We apply this scheme to uplink cellular communication where the base station lies on the middle of the X-Y plan and the two mobiles move on the plane such that their locations are symmetric around the Y axis. Results show where it is beneficial to use JSDC such that there is a significant improvement on the achievable rates. Results also illustrate that the efficient region of JSDC enlarges as the destination power increases.

 

 

 

Relay Channel with relay-destination cooperation (RDC)

The relay channel with RDC can be obtained as a special case of MAC-SDC when one of the two sources has no information to send and it only functions as a relay for the other source.

Asymptotic capacity achieving for the individual rate

 We can show that the proposed scheme achieves the capacity by reaching the cut-set bound as the destination power approaches infinity.

Figure 5 compares between the achievable rate of the RDC, classical partial decode-forward (PDF), noisy network coding, and the cut set bound

Figure 6 shows that the proposed RDC scheme achieves the cut-set bound when the destination power (Pd) approaches infinity.

Figure 5
Figure 5
Figure 6
Figure 6

 

 

 

 

 

 

 

 

 

 

 

Interference Channel with Destination Cooperation:

This project considers the interference channel with destination cooperation. As shown in Figure 1, this cooperation can be applied in uplink cellular networks via the backhaul network connecting the base stations. We consider different encoding and decoding techniques and compare these various techniques.

Encoding and Decoding Techniques:

For the encoding techniques, we consider standard Han-Kobayashi (HK) techniques at both sources as well as quantize-forward (QF) and compress-forward (CF) relaying at the destinations. For the decoding techniques, we compare backward and sliding window decoding at both destinations.

We prove the following:

  • The achievable rate regions obtained with QF and CF relaying are the same as long as the same decoding technique is used by the destinations.
  • With backward decoding, QF and CF relaying techniques achieve the same rate region as that obtained by the HK with noisy network coding (NNC) scheme. Therefore, QF relaying is the preferred scheme because it is simpler than both CF relaying and NNC and still leads to the same rate region.

Numerical Results:

Figure 7. Gaussian IC-DC.
Figure 7. Gaussian IC-DC.

Figures 8 and 9 show the achievable rate region for the Gaussian IC-DC in Figure 7 with normalized direct links while the interference (c14 and c23) and cooperative (c34 and c43) links are given in each figure.

Results show that destination cooperation is more efficient in the strong IC than in the weak IC. Also, if the destinations have enough power or the inter-destination links are very strong, sliding window decoding achieves almost the same rate region as backward decoding but with a much shorter decoding delay.

 

 

 

 

 

Figure 8. Comparison between different IC-DC schemes and the HK region in weak interference (BD: backward decoding).
Figure 8. Comparison between different IC-DC schemes and the HK region in weak interference (BD: backward decoding).
Figure 9. Comparison between different IC-DC schemes and the HK region in strong interference (SWD: sliding window decoding).
Figure 9. Comparison between different IC-DC schemes and the HK regionin strong interference (SWD: sliding window decoding).

 

 

 

 

 

 

 

 

 

Publications:

  1. “An Asymptotically Capacity-Achieving Scheme for the Gaussian Relay Channel with Relay-Destination Cooperation,”
    A. Abu Al Haija and M. Vu, 47th Annual Conf. on Information Sciences and Systems (CISS), Mar 2013.
  2. “Analysis of Encoding and Decoding Techniques for the Interference Channel with Destination Cooperation,”
    A. Abu Al Haija and M. Vu, 47th Annual Conference on Information Sciences and Systems (CISS), Mar 2013.
  3. “Efficient Use of Joint Source-Destination Cooperation in the Gaussian Multiple Access Channel,”
    A.Abu Al Haija and M. Vu, IEEE International Conference on Communications (ICC), June 2013.