Abdulaziz Mohamad

Outage achievable rate analysis for the Non Orthogonal Multiple Access Multiple Relay Channel

In this paper, we derive the individual and common symmetric ε-outage achievable rate for the relay assisted cooperative communication scheme, coined Non Orthogonal Multiple Access Multiple Relay Channel (NOMAMRC), defined as follows: (1) The sources are independent and want to communicate with a single destination with the help of multiple relays; (2) Each relay is half-duplex and apply a Selective Decode and Forward (SDF) strategy, i.e., it forwards only a deterministic function of the error-free decoded messages; (3) The sources are allowed to transmit simultaneously during both the listening and transmission phases of the relays. In this paper, the links are independent. No channel state information at transmitter is available, each link follows a slow Rayleigh fading distribution.

Outage analysis of various cooperative strategies for the Multiple Access Multiple Relay Channel

In this paper, we study the individual and common symmetric ϵ-outage achievable rates of various cooperative strategies adapted to the slow fading Multiple Access Multiple Relay Channel (MAMRC). Channel links are independent and subject to slow Rayleigh fading and additive white Gaussian noise. No Channel State Information at the Transmitter (CSIT) is available. Common to all investigated cooperation schemes are the following assumptions: (1) The sources are independent and want to communicate their messages to a single destination with the help of multiple relays using Joint Network Channel Coding (JNCC) and Decoding (JNCD); (2) Each relay is half-duplex and applies a Selective Decode and Forward (SDF) cooperative strategy, i.e., it forwards a deterministic function of the source messages that are decoded without errors. The cooperation schemes differ in the assignment of the available channel uses to the sources and the relays, ranging from the less efficient orthogonal assignment where sources and relays are given non-overlapping channel uses to the most efficient one where sources and relays can transmit simultaneously in all available channel uses.

Outage analysis of Dynamic Selective Decode-and-Forward in slow fading wireless relay networks

In this paper, we consider a slow fading Multiple Access Multiple Relay Channel (MAMRC) defined as follows: (1) Multiple statistically independent sources communicate with a single destination with the help of multiple half-duplex dedicated relays; (2) The links between the different nodes are independent, and subject to slow fading and additive white Gaussian noise; (3) Sources and cooperating relays interfere (non-orthogonal transmission); (4) No Channel State Information (CSI) at senders and perfect CSI at receivers is available and no feedback is allowed. We introduce an advanced Decode-and-Forward (DF) protocol, referred to as Dynamic Selective Decode and Forward (D-SDF), where each relay individually decides the end of its listening phase and the beginning of its cooperation phase based on a predefined selection strategy. We analyse the outage behavior of this protocol under the assumption that each relay sender employs joint network channel coding and each receiver implements joint network channel decoding, and demonstrate that D-SDF outperforms static SDF in a variety of transmission scenarios.

Cooperative Incremental Redundancy Hybrid Automatic Repeat Request Strategies for Multi-Source Multi-Relay Wireless Networks

In this letter, we present several cooperative incremental redundancy hybrid automatic repeat request strategies for the slow-fading half-duplex time slotted multiple access multiple relay channel. At a given retransmission round, the proposed strategies main steps are: 1) the destination acknowledges the successful decoding of the sources via limited feedback control channels; 2) the relays inform the destination about the result of their own decoding via forward coordination control channels; 3) the destination schedules the re-transmission in order to minimize the common outage probability of the system with the overall goal to maximize the long-term aggregate throughput; and 4) the scheduled relay cooperates with a subset of the successfully decoded sources (implicitly or explicitly indicated by the destination) applying either distributed coding or joint network channel coding. The analytical derivation of the individual (per source) and common outage probability plays an essential role in the scheduling algorithm and the performance evaluation. Numerical results show that the proposed strategies with control channels significantly outperform the one without control channels even when the impact of the control overhead is taken into account.