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This paper presents a comparison between CDMA and SC-FDMA for reverse link (RL) cellular voice and data communications. The comparison is based on CDMA2000 1x (circuit-switched voice), CDMA2000 1xEV-DO (packet data) and 3GPP LTE Release 8 (SC-FDMA based packet voice and data). We illustrate various modes of LTE system operation and associated trade-offs. For the comparison of data communications we...
Frequency reuse is a key concept for interference mitigation and thereby enhancing cell-edge performance in OFDMA networks. Two representative strategies are Fractional Frequency Reuse (FFR) and Soft Frequency Reuse (SFR). Both divide a cell into a center zone and an edge zone, and differentiate their levels of frequency reuse. Previous work on FFR and SFR has focused on networks of relatively small...
In this paper, a novel interference coordination scheme based on Dynamic Resource Allocation (DRA) for mitigating inter-cell interference in Long Term Evolution (LTE) cellular systems is presented. In both OFDMA and SC-FDMA systems, inter-cell interference is the most important interference source. Inter-cell interference coordination is considered to improve coverage and increase date rate at cell...
This paper focuses on the adaptive resource allocation strategies for two-hop multiuser OFDMA nonregenerative relay networks considering both maximization of total throughput and fairness constraints among users. First, an optimal resource allocation scheme to maximize the overall data rate is developed with separate transmit power constraints both at source and relay nodes. An alternative scheme...
Abstract-In this paper, we propose a dynamic OFDMA based subcarrier/power allocation scheme, which aims to balance the aggregate rate and the achieved TCP throughput of competing TCP flows. The proposed allocation utilizes the theoretical TCP throughput which can be accomplished in the end-to-end path. In doing so, the TCP aware scheme attempts to minimize the gap between the allocated rate and the...
This paper considers multiaccess control for the uplink in orthogonal-frequency-division-multiple-access (OFDMA) wireless networks. To avoid extensive information exchange with the access point in centralized approaches, we propose a distributed threshold-based scheme, where each user accesses multiple channels simultaneously based on a comparison between measured channel gains and a channel gain...
We consider subcarrier assignment and power allocation in OFDMA wireless mesh networks. Traditional full spatial reuse increases bandwidth efficiency but ignores multiuser diversity in the multi-hop network. Our method enables fractional spatial reuse with which multiuser diversity can also be exploited. The original optimization problem is decomposed into three tractable subproblems. First, subcarrier...
We consider the downlink of an Orthogonal Frequency Division Multiple Access (OFDMA) network. OFDMA transmission technology will be used in the next generation of wireless networks such as the LTE (Long Term Evolution) and WiMAX wireless standards. In such a channel, multiple User Equipments (UE) may each be allocated multiple Resource Blocks (RBs) in each frame. A RB is a collection of subcarriers...
This paper presents a novel fair scheme for resource sharing between nodes in OFDMA mesh networks. The problem is to maximize the overall system rate, under each user's maximal power and minimum rate constraints. To solve the underlying problem, we propose an approach that combines the merits of the well known Lagrange dual framework and the Lambert-W function. By using the Lambert-W function, resource...
Recently, there has been a great interest in cognitive radio networks. In addition, the use of subchannel allocation and power distribution in OFDM systems have been discussed in the literature and proven to help improve the capacity performance in cooperative networks. Therefore, in this paper we propose to add a primary source-destination pair to the secondary system in a cognitive radio network...
This paper considers the downlink of a cellular orthogonal frequency division multi-access (OFDMA) system, in which multiple base stations (BS) are coordinated by a centralized resource allocation algorithm. We address the problem of maximizing the weighted sum min-rate (WSMR) subject to a total power constraint at each BS, in terms of jointly optimizing coordinated BSs' subcarrier and power allocation...
This paper studies the joint OFDMA resource allocation and QoS routing problem in a hybrid wireless network, which includes an OFDMA based cellular network and an ad-hoc network with many sensor nodes. In such application, each sensor node generates certain amount of data that need to be sent to cellular base station (BS). The cellular nodes act as gateway to forward all the uplink traffic. We formulate...
This paper proposes a self-organized power allocation technique to solve the interference problem caused by a femtocell network operating in the same channel as an orthogonal frequency division multiple access cellular network. We model the femto network as a multi-agent system where the different femto base stations are the agents in charge of managing the radio resources to be allocated to their...
Single-carrier frequency division multiple access (SC-FDMA) has been decided to be adopted in the uplink of the future wireless communication system. Interleaved frequency division multiple access (IFDMA), whose transmitted signal is generated in the time domain, is a candidate of SC-FDMA. The number of comb like spectrum and the spectral interval between each spectrum depend on the number of transmission...
In this paper, we develop a distributed sub-carrier allocation algorithm with a low complexity in OFDMA multi-cell system , which is decomposed into two sub-problems: inter-cell and intra-cell sub-carrier allocation. During inter-cell process, based on time-variant characteristics and performance differ-ences among cells of sub-carriers, each base station applies Ant Colony Optimization (ACO) to choose...
In this paper, we propose a new adaptive subcarrier allocation for a multiuser two-way OFDMA relay network. In the proposed algorithm, subcarriers are allocated to the user-pairs and relays to maximize the achievable sum-rate over all user-pairs while satisfying the minimum rate requirement for each user-pair. Simulation results show that the proposed algorithm improves spectral efficiency and fairness.
This paper investigates proportional fairness-oriented scheduling issues for multihop OFDMA systems with multiple relays. Based on the idealized L-hop linear network model, three adaptive proportional fair scheduling (PFS) algorithms, namely optimal PFS, iterative user pairing (IUP) PFS and successive distributed (SD) PFS, are proposed for multihop OFDMA systems. Different with the existing scheme...
In this paper, we consider a downlink resource allocation algorithm in multi-cell Orthogonal Frequency Division Multiple access (OFDMA) systems. The resource allocation problem is modeled as a non-cooperative game. We define a specific utility function that can represent the capacity maximizing against co-channel interference in multi-cell. Then we present the resource allocation game that employs...
This paper proposes a novel distributed QoSguaranteed multi-cell radio resource allocation (RRA) scheme for OFDMA systems, which includes two separate steps operated on two time levels: the Hungarian algorithm based intra-cell fast scheduling on the frame level and the X2 interface based inter-cell interference coordination (ICIC) algorithm performed on the super-frame level. The scheme is distributed...
Various standardization activities leading to 4G and beyond networks have considered the synergy of OFDMA and multihop relaying thus giving way for the fixed relay station (FRS)-based radio access network. As such, the next-generation networks will comprise a plethora of performance enhancing devices among which is the plug-and-play nomadic relay station (NRS). It is essential for such dense and inevitably...
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