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In this paper, a point-to-point orthogonal-frequency- division multiplexing (OFDM) system with a decode-and- forward (DF) relay is considered. The transmission consists of two hops. The source transmits in the first hop, and the relay transmits in the second hop. Each hop occupies one time slot. The relay is half-duplex, and capable of decoding the message on a particular subcarrier in one time slot,...
We consider wireless telecommunications systems with orthogonal frequency bands, where each band is referred to as a channel, e.g., orthogonal frequency-division multiple access (OFDMA). For a given snap-shot in time, two joint channel assignment and power allocation optimization problems are presented, one in downlink and one in uplink. The objective is to maximize the minimum total Shannon capacity...
This paper provides a unified framework for the joint optimal subchannel and resource allocation in multi-hop relay network. Specifically, we use a simple rearrangement inequality and show that seemingly difficult problems can be efficiently solved. This includes several existing solution methods as special cases. The proposed framework can be applied to the MIMO relaying and multi-hop OFDM.
This paper investigates the problem of multiuser video transmission over downlink OFDMA networks. Two schemes, named quality-maximizing and quality-fair, are proposed and analyzed, which are to maximize the video quality without and with fairness constraint, respectively. The novelties of the schemes are characterized by the video application driven and the joint solution to the packet scheduling...
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...
Cooperative OFDM transmission is an efficient solution to combat wireless channel fading and to increase system throughput in future board communication. In this paper, we consider the uplink scenario of a cellular cooperative OFDM network, in which multi-relays can forward the source's message to base station. The uplink throughput is optimized by using decode-and-forward (DF) opportunistic relaying...
In this paper, we consider the optimal resource allocation problem for dual-hop systems with a source-destination pair and multiple decode-and-forward (DF) relays. Orthogonal frequency division multiplexing (OFDM) is adopted in both hops. To maximize the system capacity, we formulate a mixed binary integer programming problem to optimally allocate the subchannels and transmit power for both the source...
OFDM multihop system is efficient scheme to save energy and extend coverage. In this paper, optimal resource allocation in OFDM multihop system, including arbitrary number of hops and subcarriers, is studied. By joint subcarrier matching and power allocation, our goal is to maximize system capacity with the system-wide power constraint. First, we formulate the optimal subcarrier matching and power...
In this paper we consider the problem of data-aided synchronization in the up-link of a multiple access (MA) orthogonal frequency division multiplexing (OFDM) system based on offset quadrature amplitude modulation (OQAM). In particular, the joint maximum-likelihood (ML) phase offset, carrier-frequency offset (CFO) and symbol timing (ST) estimator exploiting a short known preamble embedded in the burst...
In this paper, both distributed and adjacent subchannelization modes for WiMAX system based on IEEE 802.16d standard are investigated. Sensitivity to the co-channel interference is evaluated for each mode in downlink communications. We provide a comparative analysis in terms of spectrum efficiency and present a new scheme to enhance the system performance. Our solution proposes a joint deployment...
We propose the optimal resource allocation for wireless multi-destination relay systems with orthogonal frequency division multiplexing (OFDM) modulation, which includes subchannel allocation (SA), subchannel pairing (SP), and joint source-relay power allocation (PA). Our work is different in that we consider a practical downlink OFDM based cooperative network, where the relay is used to help the...
In this paper, we consider a two-hop orthogonal frequency division multiplexing (OFDM) relay link, and investigate the system capacity in hybrid forward (HF) relay through the power allocation (PA). The expression of the system capacity in HF relay is provided. Two situations about the power constraint are concerned, and under each situation, the selection criterion among different forwarding schemes...
A two-hop relaying system where a source communicates with its destination through multiple relay nodes is studied for capacity maximization. Amplify-and-forward (AF) relaying is adopted for its simplicity. Taking the independent channel transfer function of different subcarriers and links into consideration, we formulate a resource allocation optimization problem for joint subcarrier assignment,...
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