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It goes without saying that the femtocells will be widely employed in the next generation wireless networks since the femtocells improve indoor capacity and coverage with low power and less cost. However, as the femtocells become popular, the femtocell users suffer from the complicated two-tier interference, including the macrocell-to-femtocell and femtocell-to-femtocell interference. Therefore, the...
The challenges with deploying a cellular wireless communication network with static frequency reuse in an interference limited environment is that for highly loaded cells, significant regions of coverage will experience high interference levels, resulting in unserviceable low signal-to-interference values. Therefore, interference mitigation approaches as adaptive fractional frequency reuse are considered...
This paper addresses the issue of wireless resource allocation of a Mobile WiMAX cell based on OFDMA access technique. We compare two strategies: the MAX SNR which is the most used channel assignment technique and our proposal which is based on channel condition learning. As we distinguish four IEEE 802.16e-2005 service classes: UGS, rtPS, nrtPS and ErtPS, we combine these strategies with a scheduler...
The multi-access orthogonal frequency division multiplexing (OFDMA) technology has drawn a lot of attention in next generation wireless mobile communications. It is well-known that carrier frequency offsets in OFDMA systems can destroy the orthogonality among subcarriers and produce intercarrier interference (ICI) and multiuser interference (MUI). In our previous works, we proposed a common carrier...
In order to reduce the peak-to-average power ratio property, single-carrier frequency-division multiple access (SC-FDMA) has been selected as the uplink access scheme in the Long Term Evolution (LTE) system. Aiming to derive the maximum performance of the LTE uplink in terms of both average cell throughput and cell-edge user throughput, the optimization formulation of packet scheduling problem in...
In this paper, we propose an adaptive cross-layer radio resource allocation (CL_ARRA) scheme, which is compatible with the IEEE 802.16e-2005 Orthogonal Frequency Division Multiple Access (OFDMA) air interface. The scheme comprises two steps: dynamic subcarrier allocation (DSA) and dynamic power allocation (DPA). Using DSA and DPA, we obtain a cross-layer function to maximize the system throughput...
In this paper, we study the resource allocation problem in relay aided two-hop uplink multi-user transmission with a single relay node and a single destination node. The orthogonal frequency division multiple access (OFDMA) is adopted as the main transmission modulation. We investigate the problems of subcarrier allocation, subcarrier coupling, and power allocation. The optimization is formulated...
The Multiple-Input Multiple-Output based Orthogonal Frequency-Division Multiple Access (MIMO-OFDMA) is a promising high rate air interface technology. It is well known that the capacity and coverage of such a system can be significantly enhanced by employing a proper resource allocation (RA) scheme. In this paper, a SVD based precoder and two corresponding adaptive RA algorithms for MIMO-OFDMA networks...
Capacity and coverage of a Frequency Division Multiple Access (OFDMA) network can be greatly enhanced by dynamically allocate the radio transmission resources. By including the radio resources of cooperative nodes and taking into account the fairness issue, we present a simple suboptimal solution to the problem of radio resource allocation in relaybased OFDMA cellular systems. We restrict our investigation...
The deployment of relay stations in OFDMA cellular networks is a promising solution to provide ubiquitous high-data-rate coverage. However, it makes the resource allocation a more crucial and challenging task. In OFDMA relay-enhanced cellular networks, we formulate the optimal instantaneous resource allocation problem including path selection, power allocation and subchannel scheduling to achieve...
This paper investigates the downlink burst allocation problem in IEEE 802.16 OFDMA system. In order to increase the subchannel utilization and to improve the network throughput, a channel-aware renumbering (CSR) scheme and a channel-aware downlink burst allocation (CDBA) scheme are proposed in this paper. CSR considers the difference among subchannel qualities of MSs and logically renumbers the subchannels...
In this paper we focus on the subcarrier allocation for the uplink OFDMA based cooperative relay networks. Multiple cells were considered, each composed of a single base station (destination), multiple amplify and forward (AF) relay stations and multiple subscriber stations (sources). The effects of inter-cell interference (ICI) have been considered to optimize the subcarrier allocation with low complexity...
To mitigate inter-cell interference (ICI) and achieve higher spectrum efficiency, fractional frequency reuse (FFR) has been widely adopted by the next generation wireless systems, wherein different frequency reuse factors are applied to cell center and cell edge zones. In such conventional FFR, a contiguous radio spectrum is partitioned in a fixed fashion across all cells for edge and cell center...
Due to the AMC (Adaptive Modulation and Coding) mechanism adopted in the 802.16e physical layer, each connection's spectrum requirements depend on its SNR (Signal-to-Noise Ratio). Meanwhile, according to the OFDMA functionality, the limited transmission power of every terminal is divided among the simultaneously allocated subcarriers, i.e. a terminal's uplink SNR is reversely proportional to the number...
Orthogonal frequency-division multiple access (OFDMA) exploits the frequency selective property of a wireless communication channel by allocating subchannels to individual users. Conventional multicast systems, however, suffer from diversified channel conditions among users. The main contribution of this paper is to maximize the multicast rate of one multicast session while being fair among users...
Femtocell has been considered by the wireless industry as a promising solution not only to improve indoor coverage, but also to unload traffic from overburdened macrocell networks. In hybrid macro/femto networks, macrocells may have to share the same spectrum with femtocells, due to spectrum availability and network infrastructure considerations, in spite of potentially excessive interference caused...
We have focused on SC-FDMA based resource allocation in uplink cellular systems. Subchannel and power allocation constraints specific to SC-FDMA are considered. We considered a binary integer programming-based solution recently proposed for weighted sum rate maximization and extended it to different problems. We considered problems such as rate constraint satisfaction with minimum number subchannels...
Radio resource allocation algorithm is proposed for multiuser MIMO-OFDM environment providing proportional fairness. Familiar MIMO radio channel model is extended for OFDMA transmission, exploiting multiuser diversity. Antenna selection is realized for maximizing overall data rate based on MIMO channel estimation. Adaptive M-QAM modulation is performed on selected antennas on each subcarrier, taking...
In this paper we extend the base station (BS) assignment problem to incorporate backhaul related constraints into the assignment decision. This is motivated by the fact that the deployment of more spectral efficient radio access technologies are currently imposing stringent bandwidth requirements at cell sites, and there is a growing concern that backhaul network can become a new network bottleneck...
This work investigates the problem of resource allocation (in terms of transmit powers and subchannel assignment) in the uplink channel of an orthogonal frequency division multiple access (OFDMA) network, populated by mobile users with constraints in terms of target transmit data rates. The optimization problem is tackled with the analytical tools of coalitional game theory, and a simple and practical...
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