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We introduce an opportunistic interference mitigation (OIM) protocol for cellular networks, where a user scheduling strategy is utilized in uplink K-cell environments with time-invariant channel coefficients and base stations (BSs) having M receive antennas. In the OIM scheme, each BS opportunistically selects a set of users who generate the minimum interference to the other BSs. We consider two OIM...
We study the impact of higher-order sectorization (up to 12 sectors per cell site) in cellular networks with low angle spread and a high density of users. Under ideal sector patterns (with no intersector interference), the mean throughput per site scales directly with S, the number of sectors per site. Fixing the number of antennas per site to be 12, higher-order sectorization with S = 12 and single-antenna...
Base station coordination is an efficient technique to transcend the limits on spectral efficiency imposed by intercell interference. In this paper, we compare the performance of different coordination strategies with different amount of channel state information (CSI) and data sharing among the coordinating base stations. We focus on the effect of limited backhaul capacity in a two-cell network....
As the interests of broadcasting services in mobile networks are increased, the research of convergence services of broadcasting and communication has become popular. To support broadcasting services in cellular network smoothly, WiBro support the multicast and broadcast service (MBS). MBS is transmission method that base stations belong to same MBS zone transmit the data to all users who request...
In the next generation mobile communication systems, high speed data services are expected. However, an unacceptably high transmit power is required. Multi-hop technique can solve this problem. To reduce the transmit power, while increasing the transmission data rate, we have proposed a wireless multi-hop virtual cellular network (VCN). In this paper, we introduce the multi-hop VCN for high speed...
The traditional proportional fair scheduling algorithm can only provide users with limited fairness while the channel is changing. To solve this problem and enhance the fairness between users, an adaptive proportional fair scheduling algorithm for LTE (Long term Evolution) system is proposed. It adjusts the scheduling priority according to individual user's channel condition. The proposed algorithm...
Inter-cell interference is a main reason for performances degradation in cellular systems due to usage of same frequency channels in neighbouring cells. OFDMA and SC-FDMA, used as multiple access techniques in LTE, enables fractional frequency reuse as one of the methods for Inter-cell interference cancellation. Several papers are already treating influence of fractional frequency reuse on performances...
Subcarrier and power allocation plays an important part in optimizing the performance of OFDMA systems. However, inter-cellular interference is often neglected in resource allocation. In this paper, with the inter-cell interference taken into account, we propose a subcarrier and power allocation framework based on Game Theory in uplink OFDMA multi-cellular systems. In this algorithm, the subcarrier...
Fractional Frequency Reuse (FFR) is one of the key concepts for mitigating inter-cell interference and improving cell-edge performance in OFDMA networks. The standard FFR scheme is intuitive and optimal for the hexagon-shaped cell pattern. In contrast, real-life OFDMA systems have very irregular cell layout, thus the number of surrounding cells and their respective interference vary significantly...
Distributed antenna systems (DAS) add remote radio units with one or more antennas to enhance coverage and capacity in cellular systems. DAS works by connecting the remote radio units to the base station via a high bandwidth and low latency link. This paper analyzes multiuser multiple input multiple output (MIMO) DAS and compares it with multiuser MIMO communication without DAS in terms of per-user...
In this paper we apply constrained optimization techniques to optimally allocate bandwidth and transmit power to the users in a cellular network. We utilize partial frequency reuse with one user in the full and one user in the partial frequency reuse regions as inter-cell interference mitigation technique. We show that the non-convex sum-rate maximization problem becomes convex under some simplifying...
In this paper we design high performance multiple-input-multiple-output (MIMO) receivers for the DFT-Spread-OFDM based long term evolution (LTE) cellular uplink. In the LTE uplink multiple single-antenna users can be scheduled on the same time-frequency resource block via space division multiple access. The designed receivers are also applicable to the LTE-Advanced cellular uplink wherein simultaneous...
The performance of a multicell wireless network is often limited by intercell interference. This paper considers the use of common-private message splitting at the transmitter and common-message decoding at the receiver for intercell interference mitigation. For a downlink multicell system with multiple antennas at the base-stations and single antenna at the mobiles, we utilize a heuristic SDP-relaxation-based...
Frequency Assignment is an important approach to mitigate multi-cell interference in cellular systems. In this paper, we consider frequency hopping as one possible frequency assignment approach. In particular we focus our attention on cognitive radio cellular systems as one of the very promising future access technologies, taking IEEE 802.22 as an example. While the optimal frequency assignment for...
In this paper, we propose a new dynamic frequency assignment scheme for femtoCells in OFDMA networks. The femtoCell base stations are small cellular base stations specially designed to improve the poor indoor coverage and increase the system capacity for cellular and wireless broadband networks. However, these femto-base stations cause harmful interference to the macroCells. Therefore, the optimization...
The objective of the present paper is to propose a rapid and accurate method for the evaluation of the quality of service (QoS) perceived by the users in the uplink of wireless cellular networks. In doing so we aim to account for the dynamics induced by the arrivals and the departures of the users. In particular, the QoS is evaluated in terms of the blocking probability for streaming users and the...
Femtocells are low-power base stations which improve signal coverage in indoor environment. In order to deploy femtocells in macro cells, one of the essential issues is to evaluate the interferences towards the mobile users served by the macro cells. In this paper we mainly analyze the system performance of TD-SCDMA cellular radio network for HSDPA data services when operating femtocells. The fixed...
This paper presents a unique concept of `Spotlight coverage' for outdoor multi-antenna (or DAS) cellular systems. This concept helps in achieving high Signal-to-Interference Ratio (SIR) throughout the cell coverage area by effectively controlling the leakage into the neighboring cells. Interference and coverage analysis of traditional wall mounted and street lamp mounted (providing spotlight coverage)...
In order to to solve the near-far problems, uplink power control has been adopted as a key feature in many cellular radio systems. In this paper, we provide a joint minimum bit error rate multiuser detection and bit-error-rate based (MBER-BER) uplink power control method, and demonstrate its performance in both additive white Gaussian noise (AWGN) and frequency selective fading channels. Our simulation...
Due to the requirement of high spectrum efficiency, the frequency reuse of one is targeted for next generation OFDMA-based cellular networks. Such a frequency planning strategy can lead to unacceptable inter-cell interference levels experienced especially by users located at the cell edge area. Soft frequency reuse (SFR) is considered as an effective frequency reuse scheme for inter-cell interference...
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