A Cooperative NOMA User Pairing in UAV-Based Wireless Networks

NOMA (non-orthogonal multiple access) will be seen as a promising technology for enhancing spectrum efficiency in future cellular networks. The use of unmanned aerial vehicle (UAV) Amplify-and-Forward (AF) relaying as a moving access point or BS, on the other hand, has emerged as a potential solution to wireless networks' high traffic demands. In this paper, we study joint user pair and resource allocation-based distance to optimize fair throughput in a downlink scenario, which concentrates on UAV-aided communication from different wireless-powered nodes. Several transmission methods are proposed, including NOMA as well as UAV cooperative relaying and two representative node-pairing strategies. The simulation results illustrate that the proposed user pairing strategies for cooperative NOMA and UAV-based cellular networks enhance downlink transmission performance and ensure optimum use of power and bandwidth resources.Comment: 5 pages, 4 figure

Subspace Coding for Error Control and Interference Mitigation in Routing Solutions with Cooperative Destination Nodes

Random Linear Network Coding (RLNC) is a transmission scheme that opts for linear combinations of the transmitted packets at a subset of the intermediate nodes. This scheme is usually considered when Network Coding (NC) is desired over non-coherent networks. In order to integrate error correction in RLNC, subspace codes have been proposed. The codewords in those codes are unchanged under rank-preserving row operations, making them convenient for RLNC. In this paper, we investigate the use of those codes for the interference channel in a system model consisting of an array of SISO communication systems with cooperative destination nodes. This system model is deemed as a simplified model of a network with a routing based transmission scheme. Results have indicated that the use of subspace codes have allowed for better performance in terms of the decoding failure probability.Comment: (5 pages, 5 figures, conferenc

Multiple description coding technique to improve the robustness of ACELP based coders AMR-WB

In this paper, a concealment method based on multiple-description coding (MDC) is presented, to improve speech quality deterioration caused by packet loss for algebraic code-excited linear prediction (ACELP) based coders. We apply to the ITU-T G.722.2 coder, a packet loss concealment (PLC) technique, which uses packetization schemes based on MDC. This latter is used with two new designed modes, which are modes 5 and 6 (18,25 and 19,85 kbps, respectively). We introduce our new second-order Markov chain model with four states in order to simulate network losses for different loss rates. The performance measures, with objective and subjective tests under various packet loss conditions, show a significant improvement of speech quality for ACELP based coders. The wideband perceptual evaluation of speech quality (WB-PESQ), enhanced modified bark spectral distortion (EMBSD), mean opinion score (MOS) tests and MUltiple Stimuli with Hidden Reference and Anchor (MUSHRA) for speech extracted from TIMIT database confirm the efficiency of our proposed approach and show a considerable enhancement in speech quality compared to the embedded algorithm in the standard ITU-T G.722.2

Joint Channel Coding and Cooperative Network Coding on PSK Constellations in Wireless Networks

In this paper, we consider the application of Reed- Solomon (RS) channel coding for joint error correction and cooperative network coding on non-binary phase shift keying (PSK) modulated signals. The relay first decodes the RS channel coded messages received each in a time slot from all sources before applying network coding (NC) by the use of bit-level exclusive OR (XOR) operation. The network coded resulting message is then channel encoded before its transmission to the next relay or to the destination according to the network configuration. This scenario shows superior performance in comparison with the case where the relay does not perform channel coding/decoding. For different orders of PSK modulation and different wireless configurations, simulation results demonstrate the improvements resulting from the use of RS channel codes in terms of symbol error rate (SER) versus signal-to-noise ratio (SNR).Comment: 6 pages, 4 figures, conferenc

Effective Capacity Analysis of H-ARQ Assisted Cooperative Communication Systems

In this paper, the effective capacity of cooperative communication (CC) systems with hybrid Automatic repeat request (HARQ) is derived. The derived expressions are valid for any channel distribution and with any arbitrary number of retransmissions by the source and relay for both HARQ-repetition redundancy (RR) and HARQ-incremental redundancy (IR) over asymmetric channels. As an example, we use the derived EC expression over Rayleigh fading channels. Several results are obtained for a low rate and signal-to-noise ratio (SNR). We can see that the EC attends its maximum value with a small number of retransmissions. As expected when the relay-destination channel has low SNR, it is better than the relay does not participate especially when we assign a large number of transitions at the relay. For high data rates and strict quality of service (QoS) constraints, it is better to increase the number of relay transmissions. Finally, when we increase the number of source retransmissions, the effective capacity improves even for low values.Comment: 30 pages, 6 figure

Joint Voice/Video Retry Limit Adaptation for On-Demand Streaming over WiFi Networks

This letter proposes a fast retry limit adaptation algorithm for the 802.11e distributed networks. Different from existing solutions, which manage a unique access category, the presented method jointly estimates the retry limits associated with both voice and video packets. The algorithm that operates in saturated and non-saturated traffic conditions is validated adopting an 802.11n physical layer and comparing its performance with a proper extension of an existing solution