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In this paper, we investigate the outage performance of a decode-and-forward (DF) underlay cognitive two-way relay system with direct link using time division broadcast protocol in the presence of primary user's interference. Herein, relying on the practicability and low-complexity of statistical channel state information (CSI), the secondary transmissions satisfy the fading-averaged interference...
Operating the full-duplex (FD) mode in the two-way (TW) relay system has the potential to vastly improve the spectrum utilization owing to the simultaneity of the transmission and reception on the same frequency band. However, the severe self-interference (SI) from the transmitting antenna to the local receiving antenna incurred by the FD mode will cause difficulties for decoding the desired signals...
In a cognitive radio network (CRN) of multiple secondary users (SUs) and multiple primary user channels, the protocol of allocating channel resources to SUs and the evaluation of the effectiveness of the protocol are still open issues.In this paper, we developed a novel protocol to allocate channels to SUs and an analytical criterion to evaluate the performance of this protocol.The system settings...
In this paper, we consider a two-way relay (TWR) system in which two multi-antenna source terminals communicate with the help of an energy harvesting (EH) single-antenna relay utilizing the time switching relaying (TSR) protocol. Assuming beamforming at the terminals and analog network coding (ANC) at the EH based TWR, we derive expressions for the outage probability of the system for Rayleigh fading...
In the multiuser cooperative communication, a core problem is how to efficiently find an appropriate cooperative relay node with lower power consumption and minimal payment when the number of relay nodes is large. This is referred to as optimal relay selection problem, which characterize the desired tradeoff between the probing cost for establishing cooperative transmission and the reward via the...
In this paper, we propose a novel relay selection policy based on the Hybrid Relay Selection (HRS) relay selection protocol that takes into account the state of the buffers and aims at reducing the average packet delays in the network. The proposed protocol, called the Delay-Aware HRS (DA — HRS) protocol is analyzed by means of Markov Chains and expressions for the outage probability, throughput and...
In this paper, a cooperative spectrum sharing protocol is proposed for cognitive radio networks (CRNs) which operates in underlay mode with an automatic repeat-request (ARQ)- based primary user (PU) including primary transmitter (PT) and primary receiver (PR) nodes and a bidirectionally communicating secondary user (SU) which consists of the nodes S1 and S2. In ARQ-based PU, ACKnowledgement/Negative-ACKnowledgement...
In this paper, we apply the concept of combined bulk/per-subcarrier selection to two-hop relay selection systems employing OFDM. The outage probability of the proposed strategy is analyzed in the high SNR regime when decode-and-forward, fixed-gain amplify-and-forward and variable-gain amplify-and-forward are employed at the relays. Meanwhile, a generalized situation without specifying the relaying...
This paper focuses on the achievable secrecy throughput in the hybrid automatic repeat request (HARQ) protocol over quasi-static Rayleigh fading channels for the wiretap channel model. We propose a scheme that ensures reliable and secure communication utilizing polar coding in conjunction with the HARQ protocol. Security and reliability is ensured even when the instantaneous power of the wiretap channel...
In this paper, a spectrum sharing protocol that combines coordinate-interleaved orthogonal design (CIOD) and space-time block coding is proposed for cognitive radio (CR) networks. Primary system's transmitter (PT) and receiver (PR) are equipped both by one antenna while secondary system's transmitter (ST) and receiver (SR) are equipped by two and one antennas, respectively. CIOD applied by means of...
In this paper, ergodic secrecy capacity is analyzed in a cooperative communication network, for an independent but non-identically distributed (i.n.i.d) Rayleigh fading channel. By using multi-trusted decode and forward relays, the model assumes direct links between a sender (Alice) and receiver nodes (Bob and an eavesdropper); in addition both Alice and the relay have perfect knowledge about the...
This paper proposes a selective AF-OFDM (Amplify-and-Forward, Orthogonal Frequency Division Multiplexing) relaying protocol, in which selective relaying policy is adequately utilized to improve the spectrum efficiency of cooperative multi-carrier transmission, and addresses the power minimization problem subject to a target quality of service (QoS) constraint for corresponding battery-operated systems...
Cooperative broadcasting is a promising technique for efficient as well as robust broadcast of information in ad hoc networks. The paper compares the capacity of scheduled cooperative broadcasting with the capacity of Spatial Reuse TDMA (STDMA) for broadcast traffic in ad hoc networks. Three different routing methods for STDMA are considered: a tree-based solution; default MPR-flooding; and a robust...
The focus of this work is on the design of Raptor codes for continuous variable Quantum key distribution (CV-QKD) systems. We design a highly efficient Raptor code for very low signal to noise ratios (SNRs), which enables CV-QKD systems to operate over long distances with a significantly higher secret key rate compared to conventional fixed rate codes. The degree distribution design of Raptor codes...
In this paper, an overhearing protocol is proposed for two-way cooperative multiantenna relaying systems, where the relays equipped with multiple antennas collaborate to relay signals between the base station (BS) and two user equipment units (UEs). In the proposed overhearing protocol, the UE in the uplink transmission phase transmits only in the first time slot, i.e., it remains silent in the second...
In this paper, the physical layer security of applying non-orthogonal multiple access (NOMA) in large-scale networks is investigated. In the considered scenario, both the NOMA users and eavesdroppers are spatially randomly deployed. A protected zone around the source node is adopted to enhance the security of a random network. In order to characterize the secrecy performance of the considered scenario,...
This paper presents a new accurate mathematical analysis on the performance of distributed cooperative systems employing time-based relay selection protocols. A time-based distributed protocol relates the packets' transmission time to their signal strengths such that the best relay transmits firstly and all other relays abort their transmissions once they sense a busy channel. However, this protocol...
In this paper, we consider a two-way relay system that employs transmit/receive beamforming for bidirectional communication using analog network coding (ANC) protocol in the presence of channel estimation error (CEE). For this set-up, we first obtain the instantaneous end-to-end signal-to-noise ratios (SNRs) with partial self-interference cancellation pertaining to imperfect channel estimation. Then,...
In this paper, we propose novel relay selection policies that aim at reducing the average delay by incorporating the buffer size of the relay nodes into the relay selection process. More specifically, we propose two delay-aware protocols that are based on the max — link relay selection protocol. First, a delay-aware only approach while it reduces the delays considerably it starves the buffers and...
Cooperative diversity decreases the fading in communication system. It comprises of a source, a destination and a relay to do the error analyses. Analysis is done using Equal Gain Combining (EGC) and Maximal Ratio Combining (MRC) technique with Incremental Relaying. For a cooperative diversity system employing incremental relaying, it is assumed feedback channel is present to relay from the destination...
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