Description of research projects

Figure 1: Full-duplex two-way relay channel model with general Rayleigh fading links.

Figure 1: Full-duplex two-way relay channel model with general Rayleigh fading links.

In this project, we establish and analyze a full-duplex composite decode-and-forward transmission scheme for the two-way relay channel with a direct link. During transmission, our scheme combines both block Markov coding and an independent coding scheme that resembles network coding at the relay. We design this optimal scheme from a link-state perspective in order to obtain the maximum transmission rates. By analyzing this composite scheme in Rayleigh fading, we demonstrate that relay power savings are realizable for most node configurations and highlight an inherent trade-off between achievable rate and power savings at the relay. For more details, click here.

     

     

     

  • Mobile-to-mobile Cooperation in Next Generation Cellular Networks

    Figure 1

    Figure 1

    Mobile-to-mobile (M2M) communication is a topic of interest in future 4G LTE-advanced networks. As opposed to normal M2M communication in LTE advanced in which the two mobiles only communicate between themselves, in this project, we consider M2M cooperation in the uplink transmission. This idea is illustrated in Figure 1 where two mobiles cooperate to increase their transmission rate to the base station.

    We study the performance of the proposed scheme in terms of the achievable rate region, the outer bound, and the optimal resource allocation to maximize the transmission rates and outage performance. For more details, click here

 

 

  • Source and Destination Cooperation

    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.

    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 the 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. For more details, click here

 

 

Figure 1. Half-duplex relay channel model.

Figure 1. Half-duplex relay channel model.

Relaying is attracting significant attention as a key feature of future wireless systems. Since user applications are mainly associated with a fixed minimum rate defined as a Quality-of-Service feature, in this project, we analyze coding for energy efficiency in relay channels at a fixed source rate. We first propose a half-duplex partial decode-forward coding scheme for the Gaussian relay channel shown in Figure 1. We then derive three optimal sets of power allocations, which respectively minimize the network, relay and source energy consumption. For more details, click here.

 

 

Figure 1: Full-duplex two-way relay channel model.

Figure 1: Full-duplex two-way relay channel model.

In this project, we propose various coding schemes for the two-way relay channel, which consists of two sources exchanging information with the help of a relay. We also compare between our proposed scheme and existing schemes. The proposed schemes include partial decode-forward (PDF), quantize-forward, and combined decode-forward (DF) and layered noisy network coding (LNNC) scheme. For more details, click here.

 

 

 

 

 

  • Cognitive Communications

    ZPD

    Figure 1. The full-duplex modes for the causal cognitive interference channel.

    The causal cognitive interference channel (CCIC) has two sender-receiver pairs, in which the second sender obtains information from the first sender causally. The second sender assists the first sender’s transmission, in addition to transmitting its own information. In this project, we study both the full- and half-duplex modes. In each mode, we propose two new coding schemes built successively upon one another to illustrate the impact of different coding techniques. For more details, click here.

 

 

Figure 1. The proposed private message scheme for a single-source single-destination network with N relays

Figure 1. The proposed private message scheme for a single-source single-destination network with N relays

In this project we study a practical channel in sensor and ad hoc networks, namely a relay network consisting of one source, one destination, and N relays as shown in Figure 1. We design a scheme based on the partial decode-forward (PDF) relaying scheme for this channel and show that it includes the PDF scheme for a relay channel with single relay as a special case. The proposed scheme is based on rate splitting with Nth-order superposition block Markov encoding and simultaneous sliding window decoding. For more details, click here