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In this paper, we consider the problem of resource allocation in relay aided uplink multi-user transmission with a single destination node. We adopt the amplify-and-forward (AF) relaying scheme and the orthogonal frequency division multiple access (OFDMA) as the main transmission modulation. The optimization is formulated as maximizing the end-to-end system throughput subject to limited number of...
In this paper, a new planning method is proposed for the next generation wireless networks that are based on Orthogonal Frequency Division Multiple Access (OFDMA). As a consequence of the wide variety service demands in terms of data rate and Quality of Service (QoS), the traffic pattern is considered to be heterogeneous. Therefore, the complexity of obtaining Base Stations (BSs) positions increases...
We consider a point-to-point frequency-selective orthogonal frequency division multiplexing (OFDM) channel. Based on a linear minimum mean square error (MMSE) channel estimates from pilot signals, a receiver determines a set of 'on' or active subchannels that maximizes a lower bound on a sum capacity. The capacity bound optimization is constrained to a fixed total power, which is a sum of total training...
This work addresses the application of the cross-layer paradigm to the design of efficient resource allocation algorithms for the downlink of a MIMO-OFDMA system with a physical layer employing optimal single-stream/single-user linear precoding. Mathematical programming tools are used to solve the problem of weighted throughput maximization using both channel state information from the physical layer...
This paper introduces a theoretical framework for subcarrier and power allocation algorithms in rate-adaptive OFDMA systems. The focal point is locating “capacity-achieving” waterlevels for a given allocation in order to minimize the distance to the boundary of the capacity region. We prove that it is possible to restrict the choice of waterlevels to an optimality polyhedron. This paper introduces...
We investigate the problem of multi-user radio resource allocation for orthogonal frequency division multiple access (OFDMA) amplify-and-forward (AF) relays. In the single-user case, the problem reduces to the well know assignment problem, which maximizes the user rate. For the multi-user case we devise a resource allocation algorithm to achieve max-min fairness. We find max-min fairness since it...
This paper considers an OFDMA relay network and proposes an auction algorithm for the subchannel allocation to balancing efficiency and fairness with service differentiation. This algorithm allows users to fairly compete for the using of the subchannel through a new bidding strategy. We use the second-price sealed auction mechanism under which the dominant strategy of the bidder is bidding the true...
The latest generation of wireless networks use OFDMA (Orthogonal Frequency Division Multiple Access) transmission technology in the downlink (e.g, WiMAX and LTE). The downlink is divided into bandwidth units and UEs (User Equipments) are each allocated a subset of these. Since at most one UE is assigned to each of these units, downlink transmissions within a sector are orthogonal. However, the transmission...
This paper investigated the admission control problem in multi-service cellular relay system with orthogonal frequency division multiplexing access (OFDMA). Subjected to a hard constraint on the quality-of-service (QoS) requirements and the capability of relay, the admission problem could be described as the problem of maximizing the amount of subcarriers saved by relaying transmission. With further...
We consider joint cross-layer resource allocation and inter-system interference avoidance in OFDMA-based multiuser cognitive radio (CR) systems, where the secondary users (SU) can share spectrum with the primary users (PU) without causing unacceptable interference. The objectives are to provide quality of service (QoS) to both real-time and non-real-time services for SUs, and optimize the system throughput...
Cognitive radio is one of the hot topics for emerging and future wireless communication. Cognitive users can share channels with primary users under the condition of non interference. In order to compute this interference, the cognitive system usually use the channel state information of the primary user which is often impractical to obtain. However, using location information, we can estimate this...
In this paper we propose three frequency reuse coordination schemes for interference management in OFDMA. The aim of these schemes, working together with time and frequency domain packet scheduling, is to achieve reuse of 1 at sector level in a trisectorized base station scenario. Inter-sector interference is strong at the frontier between sectors and a tight coordination scheme needs be applied....
We propose a novel distributed and low complexity joint channel and power allocation scheme for the uplink of multi-cellular multi-carrier systems. The algorithm is based on the min-sum message passing (MP) scheme that entails passing messages between the base station (BS) and mobile terminals (MTs) with the aim of achieving a low power consumption resource allocation while respecting rate constraints...
For the issue of resource allocation in a heterogeneous multi-user downlink OFDMA system with both delay-constrained (DC) and non-delay-constrained (NDC) traffic, this paper proposes suboptimal joint subcarrier and power allocation (JSPA) for channel-aware queue-aware(CAQA) scheduling. The objective is to maximize the sum of all NDC users' logarithmic utility functions (achieving proportional fairness)...
Low Density Signature-Orthogonal Frequency Division Multiplexing (LDS-OFDM) has been introduced recently as an efficient multiple access technique. High Peak to Average Power Ratio (PAPR) is an important obstacle to multicarrier communication systems. This paper concentrates on the PAPR investigation and its reduction for LDS-OFDM signals. Specifically, we will investigate the impact of subcarrier...
We propose a strategy that optimally schedules and allocates users for adaptive modulation and coding based orthogonal frequency multiple access systems (AMC-OFDMA). This strategy aims to maximize the average system throughput as a function of bit error rate (BER) and spectral efficiency by exploiting the user diversity. It sorts the available users of an assigned base station (BS) in queues based...
In this paper, we propose a spectrum division & adaptive subcarrier allocation for cooperative amplify-and-forward (AF) relay using single carrier-frequency division multiple access (SC-FDMA). To obtain increased frequency diversity gain, the transmit SC signal spectrum is divided into sub-blocks, to each of which a different set of subcarriers (resource block) is adaptively allocated based on...
With the increasing demand for multimedia services on wireless networks, it is important to optimise air interface parameters to maximise throughput and QoS. In this paper, we examine the effect of WiMAX burst mapping and Round Robin - based packet schedulers on multimedia traffic and network capacity. In this work, we have simulated the IEEE802.16e air interface to examine the downlink channel performance...
With the rapid distribution of smart grids in China, the power line communications (PLC) have been becoming a potential scheme to transmit data. For any kind of communications system that will be used in a large range, resource allocation is a very important aspect. This paper has analyzed the single-user bit and power allocation model with power self adaptation and speed rate self adaptation based...
Femtocell is one of promising key technologies to increase the efficiency and coverage of next generation broadband wireless networks. However, there exists interference problem between femtocells and macrocell due to co-channel operation. In this paper, we propose an efficient frequency resource allocation scheme for newly deployed femtocells in the legacy OFDMA networks in order to maximize the...
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