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Load balancing (LB) plays a key role in improving the performance of hybrid Geostationary Orbit (GEO)-Low Earth Orbit (LEO) satellite network. Overload is very common in LEO satellite due to the non-uniform distribution load and the periodic satellite motion. A feasible approach to realize load balancing is that the terminals (destination nodes) served by LEO satellite hand over to GEO satellite....
This paper investigates joint relay selection (RS) and power allocation (PA) in cognitive radio (CR) systems, in which relay nodes operate in amplify-and-forward (AF) mode. In contrast to the conventional schemes, we take into account the performance of the secondary user (SU) which acts as the relay. A two-step optimization scheme is proposed to maximize system throughput with minimum rate guarantees...
In this paper, we consider the problem of joint relay selection and power allocation in a cognitive radio (CR) network, where a secondary user (SU) source communicates with a secondary access point (AP) assisted by a set of SU relays. Each SU in this set not only acts as a potential relay but also has its own data transmission requirement. Keeping the interference to the primary user (PU) below a...
Relay aided wireless transmission realizes extended coverage and increases capacity for wireless communication networks, especially for the TDD/FDD LTE-A system. The relay node processes the received signal from source under certain rules and forwards the signal to destination. Amplify-and-Forward (AF) and Decode-and-Forward (DF) are two of the conventional relay schemes commonly used and cited. Estimate-and-Forward...
In this paper, the fairness issue of delay performance for the ARQ protocol in two-user cooperative system is investigated. Relay policy between users are constrained by their own delay performance. When the delay for two users vary greatly, the system will reduce to three-node cooperation networks. Short-delay user will always provide relay service to the long-delay user if necessary to quicken the...
In this paper, a novel channel estimation scheme called Two-Pilot Estimation (TPE) is proposed for distributed space-time decoding in Amplify-and-Forward (AF) based wireless relay networks. For Maximum Likelihood (ML) decoding at the destination, directly estimating the product of source-relay (S-R) channel and relay-destination (R-D) channel either is difficult, or causes drastic receiver degradation...
Rate and diversity impose a fundamental tradeoff in wireless communication. We propose a novel distributed space-time coding (DSTC) scheme based on linear constellation precoding (LCP) for Amplify-and-Forward relaying networks. The proposed scheme can achieve full-diversity or full-rate, and also offers a flexibility for a desired rate-diversity tradeoff. This scheme works well with arbitrary signal...
In this paper, we study optimum SNR threshold based partial decode-and-forward (PDF) schemes where relays may choose to forward the demodulated symbols in form of distributed space-time coding (DSTC) or to remain silent according to instantaneous link qualities of the source to relays. Considering the possible error of Maximum likelihood decoding at intermediate relays, we model a general noise in...
Cooperative communication with a single relay is a simple and effective technology for wireless sensor networks. However, its gains often come at a price in terms of extra energy consumption for relay selecting and the relaying device running. As such, we contend that it is worthwhile to consider a relaying scheme that satisfies an overall performance requirement constraint such that cooperation is...
Automatic repeat-request (ARQ) protocols for two-user cooperative diversity system employing Alamouti space-time coding are investigated in this paper. A whole cooperative transmit frame of the original cooperative system consists of three sub-frames. According to different feedback schedules in a transmit frame at the destination, two basic ARQ protocols, namely post-cooperating and pre-cooperating,...
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