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Orthogonal Frequency Division Multiplexing (OFDM) is very sensitive to carrier frequency offsets (CFO). The CFO results in intercarrier interference (ICI). This drawback of OFDM is inherited to Orthogonal Frequency Division Multiple Access (OFDMA). In this paper, we propose a new ICI model for an uplink OFDMA system that takes into account the presence of the cyclic prefix which is usually ignored...
Orthogonal Frequency Division Multiple Access (OFDMA) has already been the main multiple access technology for 3G long term evolution(LTE) and 4G. This paper analyzes characteristics of OFDMA multiple access technology and puts forward a new OFDMA handover algorithm (sub-carriers bidirectional arrayed handover algorithm, SBA). The simulation results show that, during handover process, SBA algorithm...
In the uplink of OFDMA (Orthogonal Frequency Division Multiple Access) based M-WiMAX (Mobile-Worldwide Interoperability for Microwave Access) system, linear phase shift is caused by signals transmitted from multiuser with different delay time and thus, MAI (Multiple Access Interference) occurs. MAI degrades the performance of ranging code detection and delay time estimation in the uplink. Therefore,...
This paper proposes a transmit beamforming and subcarrier power allocation method for orthogonal frequency division multiple access (OFDMA) systems based on ??signal-to-leakage-plus-noise ratio?? (SLNR). As the transmit beamforming vector control criterion, we employ the maximization of the SLNR at each base station, while the subcarrier power allocation is performed by iterative water-filling algorithm...
In this paper, we propose a three-cell network multiple-input multiple-output (MIMO) scheme to mitigate the inter-cell interference in an orthogonal frequency division multiple access (OFDMA) system with each cell using the same spectrum. One fundamental question to apply the network MIMO technique in such a high interference environment is: how many base station should coordinate together to provide...
The wireless relay mesh network (WRMN) is designed to provide robust and fault tolerant communications between relay and user nodes in broadband wireless networks. In this paper, we study interference aware resource allocation in OFDMA based WRMNs and the effects of spatial reuse on throughput. We propose an interference aware subcarrier assignment (IASA) algorithm to allocate subcarriers to links...
Recently, several works have pointed out the negative impact of intercell interference variation on the performance of link adaptation in multi-cell single input single output (SISO) systems. However, the performance of adaptive precoder selection in multiple input multiple output (MIMO) cellular networks in the presence of interference variation is much less understood. In this paper we develop a...
In this paper we present an interference aware phased scheduling strategy for a soft frequency reuse (SFR) interference coordination scheme in an Orthogonal Frequency Division Multiple Access (OFDMA) network. It groups the active user terminals (UT) in a low and high signal-to-interference plus noise ratio (SINR) group and picks UTs from both groups in each scheduling round to optimally exploit the...
We describe an algorithm for sub-carrier and power allocation that achieves out-of-cell interference avoidance through dynamic fractional frequency reuse (FFR) in downlink of cellular systems based on orthogonal frequency division multiple access (OFDMA). The focus in on the constant-bit-rate (CBR) traffic type flows (e.g., VoIP). Our approach is based on the continuous "selfish" optimization...
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