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Network lifetime is of great importance in WBANs that significantly influences the network performance and user experience. Among all the solutions to extend the network lifetime, relay mechanism plays a crucial role. However, previous works only concentrate on energy efficiency of sensor nodes regardless of energy storage diversity among sensor nodes, which may severely limit the performance of enhancing...
This paper investigates the energy efficient resource allocation for OFDM relay networks, where K users receive information via L helping relays. For such a system, an optimization problem is formulated to maximize the system energy efficiency (EE) by jointly optimizing the relay selection, subcarriers assignment and power allocation under the proportional rate constraints and available power constraint...
As the rapid growth of the data traffic, the mobile cellular network is under unprecedented operation pressure. Various of small cells with relay technologies have been proposed to bypass increased data with the status of the limited base station so far. Therefore, vehicular small cell gradually are attracting the attention of the researchers. In this paper, we discuss the communication model of the...
Deploying multiple antennas on high speed trains is an effective way to enhance the information transmission performance for high speed railway (HSR) wireless communication systems. However, how to efficiently deploy ($N\geq 2$) antennas on a train has not been studied yet. In this paper, we investigate efficient antenna deployment strategies for HSR communication systems where two multi- antenna...
In this paper, we propose a new physical layer network coding (PNC) scheme based on rateless coding for two-way relay systems which consist of two end nodes and one relay. The two-way relay channel is studied from a new perspective of end-to-end channel equivalence, and a novel end-to-end demodulator is proposed based on the resultant end-to-end equivalent channel. Unlike the conventional demodulator...
To improve the performance of a relay system with multiple channels, the following issues should be addressed. Namely, how to allocate the power at source and relay to subchannels, how to pair subchannels of the first and second hops, and which users should be scheduled to which subchannel pair. Considering these issues in the design of an optimal joint resource allocation scheme in orthogonal channels,...
In this paper we study the problem of relay-enhanced cell (REC) coverage for which relay location is optimized to maximize the achievable REC radius. The problem is investigated for both Rayleigh and Rician relay fading channels, under a pre-determined user's outage probability constraint. We propose a statistical approach to formulate the problem and develop an optimization algorithm for it. The...
Three issues should be taken into account to improve performance in relay system with multiple channels. They are, how to allocate the power at source and relay to the subchannels, how to pair subchannels of the first hop and the second hop, and which users should be scheduled to which subchannel pair. These issues are considered to design the optimal joint resource allocation scheme in multiple orthogonal...
In this paper, we will study the joint problem of power allocation, relay selection and subchannel pairing in OFDM based amplify-and-forward multiple relays system. The optimization problem of maximizing system capacity under joint power constraint at source and relays is firstly formulated. Then, based on Lagrangian dual method, an optimal algorithm to the problem is derived with high SNR assumption...
In this paper we consider the joint resources allocation in multiple channels single non-regenerative (AF) relay systems. Firstly, the optimization problem of maximizing system capacity under joint power constraint at source and relay is formulated. We adopt Lagrangian dual method to derive the optimal centralized algorithm. Through the analysis it is proven an efficient and computational tractable...
Relay selection and subchannel pairing are important issues in OFDM based cooperative wireless systems to improve the system performance and reliability. Most of the relay selection schemes in modern literatures are centralized under the assumption that the overall channel condition is known at the source node, each relay node and the destination node which is impractical. In this paper, we will propose...
In this paper we present single antenna relay channel measurements conducted in an urban environment at 2.35 GHz. Three types of links, i.e. base station to mobile station (BS-MS), relay station to mobile station (RS-MS) and base station to relay station (BS-RS), were measured at two sites. Our investigation focuses on the characteristics of large scale parameters (LSP) of the RS-MS link, which is...
Power allocation, relay selection and subchannel pairing are three important issues in OFDM based relay wireless systems to improve the system performance and reliability. In this paper, we will propose a joint power allocation, relay selection and subchannel pairing algorithm. The goal of the algorithm is to maximize the system capacity under the constraint of overall power at both source and relay...
In this paper, the sum rate issue of a multiple-input multiple-output (MIMO) relay broadcast channel is studied, where the fixed relay station is used to support multiuser transmission in a downlink channel. With appropriate design, the sum rate can be expressed as a function of the processing units at the base station (BS) and relay, and the power allocation can be converted to a standard convex...
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