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In cooperative communications, the problem of error propagation has a detrimental effect on the diversity order of the wireless system. To mitigate such an effect, we present a relaying scheme that is based on the absolute value of the log-likelihood ratio (LLR) of the received message signals at both the relay node and the destination node. The calculated LLR values are then compared to each other...
In this work, a relay-selection scheme is proposed for underlay cognitive radio networks, with fixed and adaptive relaying power. The relay-selection and power allocation is based on the calculation of the log-likelihood ratio (LLR) value, calculated at each of the relay nodes available in the secondary network. No interference is caused to the primary network, through the satisfaction of a low power...
Wireless communication has been rapidly developed in recent years acquiring higher demand of efficient wireless systems. Cooperative communication is considered to be capable of effectively meeting this rapid growth where the use of relays improves the throughput and ensures successful transmission to all terminals in a given system. In this paper, a Two-way Decode and Forward Relaying for orthogonal...
Direct Device-to-Device (D2D) communication permits to offload the network, increase the capacity, and extend the cellular coverage. In D2D systems, user equipments (UEs) do not necessarily communicate via evolved Node Base station (eNB); instead, they are allowed to communicate directly with each other. This underlying communication generates interference due to reusing the same resources of the...
One of the major problems of wireless communication is the channel estimation error and co-channel interference, which causes degradation in the performance of the system. Cooperative communication is one of the most efficient techniques to enhance the performance of wireless systems in the presence of channel estimation error and co-channel interference. In this paper, the performance of decode and...
A hybrid relaying protocol is proposed in this paper for cognitive radio networks (CRNs) under random jamming attacks of impulsive noise nature. The protocol switches between amplify-and-forward, decode-and-forward or a no-send state depending on the calculated value of the log-likelihood ratio (LLR) of the received signal at each of the randomly distributed cognitive radio (CR) nodes. A LLR-based...
Employing different relaying protocols at a relay node in a wireless cooperative network could improve the overall system performance. The choice of amplify-and-forward (AF) or decode-and-forward (DF) depends on the available set of conditions pertaining to each relay node in the system. In this paper, a hybrid relaying protocol is proposed for systems employing BPSK modulation in Rayleigh fading...
Applying network coding to a wireless cooperative communication network always proves beneficial, in terms of gains in spatial diversity, improved coverage and channel capacity. In this paper, a relay-selection method for a bidirectional (two-way) wireless cooperative communication system is proposed. A single best relay node or set of relay nodes are selected to jointly forward the combined data...
This paper proposes a relay selection scheme for wireless cooperative communication systems (CCS) utilizing a decode and forward protocol. The proposed scheme is suitable for systems employing M-ary PSK modulation schemes. A single relay node is chosen to cooperate with the direct link in delivering the message signal. This choice is based on the absolute value of the log-likelihood ratio (LLR) of...
In this paper, we propose a relay selection method for cooperative communication systems (CCS) employing the QPSK modulation scheme. The relay nodes forward their reliability to the destination node, utilizing a quantized reliability-relaying (QRR) scheme. The reliability is divided into five different levels by the relay nodes, according to the log-likelihood ratio (LLR) value of the received signal...
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