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In this paper we analyze the end-to-end capacity of subcarrier pairing strageties of OFDMA-base DF relay link over Rayleigh fading channels. We compare fixed pairing strategy to optimal pairing strategy in the circumstance that the relay is fixed or mobile.The main contribution of this paper is deriving the closed-form expressions for average end-to-end SNR and capacity in these circumstances. The...
Hop adaptive MAC-PDU (Protocol Data Unit) size optimization is proposed for Orthogonal Frequency Division Multiple Access (OFDMA) based wireless relay networks. Such optimization improves the end-to- end goodput via MAC-PDU size optimization. We provide design and evaluation for two hop cellular networks with fixed relays where the Base Station (BS) to Relay Station (RS) links are potentially robust...
Opportunistic user allocation and multiple antenna transmission provide significant performance enhancement in future wireless communication systems. In this paper, theoretical outage capacity analysis of user allocation in downlink orthogonal frequency division multiple access (OFDMA) with multiple antenna transmission and limited feedback is presented. Several multiple antenna transmission schemes...
While intercell interference coordination (ICIC) for the downlink of multi-cell systems in general and orthogonal frequency division multiple access (OFDMA) networks in particular has been extensively studied, the uplink has received less attention. For the uplink, the impact of ICIC on the overall system throughput ("the ICIC gain") must be analyzed in a system model that captures specific...
WiMAX (IEEE 802.16) is a broadband wireless access technology that enables convergence of mobile and fixed broadband networks through scalable OFDMA (Orthogonal Frequency Division Multiple Access) technology. This paper presents an analytical study of WiMAX propagation channel and estimates the channel capacity through simulation. WiMAX channel performance of different spectrum frequency bands applied...
We consider the weighted sum rate maximization problem in downlink orthogonal frequency division multiple access (OFDMA) systems. A low complexity suboptimal resource allocation algorithm is proposed for joint optimization of multiuser subcarrier assignment and power allocation. This algorithm is based on an approximated primal decomposition based method, which is inspired from exact primal decomposition...
In this paper, we compare the downlink capacity and throughput between the variable spreading factor-orthogonal frequency and code division multiple access (VSF-OFCDMA) with one-cell frequency reuse, and the orthogonal frequency division multiple access (OFDMA) with conventional three-cell frequency reuse. Since the multiuser diversity gain in OFDMA systems can be achieved by approximately designing...
This paper analyses busy burst (BB) enabled interference avoidance for multi-user orthogonal frequency division multiple access (OFDMA) in a Manhattan grid deployment scenario. Upon successful reception of data, the receiver transmits a BB in a time-multiplexed mini-slot. Exploiting the channel reciprocity of time division duplex (TDD), an exclusion region around a victim receiver is established,...
In this paper impact of resource scheduling algorithms on the average user throughput, average cellpsilas capacity and the quality of provided services in the microcellular 4G environment has been analyzed. Well known scheduling algorithms such as Round Robin, MaxSNR and Fair Rate have been compared with the algorithms proposed for fading channels in [1]. A simple modification of the scheduling has...
We propose and analyze a limited feedback scheme for downlink MIMO-OFDMA. Our analysis explicitly accounts for the feedback overhead by assuming a time division duplex system in which all feedback and data transmission must occur with a coherence time. As the fraction of coherence time devoted to feedback increases, the base station can allocate resources more efficiently, but has less time available...
This paper targets the problem of optimum power allocation and link scheduling in cellular systems. In particular, the uplink performance of OFDMA (orthogonal frequency division multiple access) is investigated. By means of heuristic relaxation, the NP-hard problem of joint power control and scheduling is transformed into one of power controlled random access (PCRA), which is formulated as a convex...
Resource allocation (RA) for OFDMA has been extensively researched with the objective of maximizing capacity while serving users in a fair manner. However, most of the previous works have focused on achieving these requirements per symbol (instantaneously). On the other hand proportional fair (PF) scheduling which is widely deployed in 3G data networks achieves the system objectives over a certain...
This paper proposes a novel approach to interference avoidance via inter-cell relaying in cellular OFDMA-TDD (orthogonal frequency division multiple access - time division duplex) systems. The proposed scheme, termed asymmetry balancing, is targeted towards next-generation cellular wireless systems which are envisaged to have ad hoc and multi-hop capabilities. Asymmetry balancing resolves the detrimental...
This paper studies the performance of orthogonal frequency division multiple access (OFDMA) in the multiuser multicarrier MIMO (M3) system for both uplink (UL) and down-link (DL) channels. We numerically quantify the performance gap between OFDMA and the optimal multicarrier solution. We also derive simple but near optimal algorithms to solve the generic OFDMA resource allocation problem in different...
Fair OFDMA (orthogonal frequency division multiple access) based subcarrier allocation algorithm is proposed. The method includes adaptive modulation and power control per subcarrier, considering actual channel state information between users and base station. To heighten dasiafairnesspsila, preliminary power control (PPC) is executed before efficient allocation of radio resources.
This paper discusses the problem of estimating the performance of an OFDMA receiver operating in a selective channel, prone to interference, wherein only a set of the OFDM sub-carriers is allocated to a user. Planning and deployment of an OFDMA system requires estimation of system performance in various signal to noise and interference (SINR) conditions. The problem is not trivial as both signal and...
The open loop transmit antenna diversity scheme and the closed loop beamforming technique are compared considering user mobility in OFDMA systems where both frequency distributed subchannelisation and frequency localised subchannelisation are provided. Outage capacity is considered for performance measurement.
In this paper, we propose an adaptive resource allocation algorithm for multiple traffic orthogonal frequency division multiple access (OFDMA) which distributes the sub-carriers and bit loading among the users according to their different Quality of Service (QoS) requirements and traffic class. From simulation results we can see that our proposed scheme decreases the outage probability for users which...
A multi-hop virtual cellular network (VCN) was proposed for future broadband mobile communication systems. Orthogonal frequency division multiple access (OFDMA) can be used as the multi-hop wireless access technique. However, since the number of available subcarriers is limited, the same subcarrier must be reused in different multi-hop links and therefore, co-channel interference limits the performance...
The next generation of wireless networks (4G) will use OFDMA (Orthogonal Frequency Division Multiple Access) in the reverse link. In OFDMA, the reverse link resources assigned to a user are called tiles each of which consists of a subset of consecutive subcarriers. Since at most one user is assigned to each of these tiles then reverse link transmissions within a sector are orthogonal. However, the...
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