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This paper presents results from a novel OFDMA multi-cell mobile broadband system level simulator. The tool is used to statistically characterize uplink and downlink inter-cell interference. Without suitable interference management, multi-billion dollar networks can collapse under the strain of heavy traffic loads. Fully loaded interference studies cannot be performed on the network until it has been...
In this paper, we study how the downlink received signal quality and throughput will be affected by deploying the Open Subscriber Group (OSG) Femtocell [1] using Location-Dependent Power Setting (LDPS) scheme with spectrum allocation (1, 3, 3) in the next generation mobile network. The LDPS scheme aims to use a suitable power for femtocell base station to maintains its indoor user coverage. The design...
In this paper, a cellular optical wireless communication system based on orthogonal frequency division multiplexing (OFDM) is simulated inside an aircraft cabin. Asymmetrically clipped optical OFDM (ACO-OFDM) and direct-current-biased optical OFDM (DCO-OFDM) transmission schemes are compared in terms of throughput and cell coverage. Cellular networks with wavelength reuse factors of 1 (full reuse),...
Inter-cell interference (ICI) is responsible for user throughput degradation and especially for users found near cell border which additionally experience serious path-losses. Efficient methods for ICI mitigation are ICI coordination (ICIC) schemes which allocate certain resources among users in different cells. In this paper we propose a decentralized ICIC scheme in order to mitigate the ICI and...
Fractional frequency reuse (FFR) is an interference coordination technique well-suited to OFDMA based wireless networks wherein cells are partitioned into spatial regions with different frequency reuse factors. This work focuses on evaluating the two main types of FFR deployments: Strict FFR and Soft Frequency Reuse (SFR). Relevant metrics are discussed, including outage probability, network throughput,...
This paper focuses on the coexistence problem of multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) systems and current radio systems such as IEEE802.11a. Aiming at improving the performance of MB-OFDM UWB, we attempt to avoid interferences from IEEE802.11a systems. The cognitive radio (CR) technology is introduced to detect the distribution of co-channel interferences...
This paper presents system level downlink performance evaluation results for the TDD based LTE-Advanced networks utilizing some of the most recent technologies for mobile systems. The main enhanced technology components used in the systems include multi-user (MU)-MIMO, intra-site coordinated multipoint (CoMP) transmission and space-time-frequency proportional fair scheduling. Performance comparison...
When fast and accurate channel state information (CSI) at the transmitter is available, opportunistic power control (OPC) is an attractive alternative to signal-to-interference-and-noise ratio (SINR) target following approaches, because it maximizes throughput by taking advantage of fast channel variations. On the other hand, in multiple-input multiple-output (MIMO) systems, open loop schemes such...
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...
In this paper, we present a new power allocation algorithm called distributed inter-cell power allocation (DIPA) that improves the throughput-fairness trade-off without inter-BS coordination for multi-cell OFDMA systems in fast time-varying environment. In order to preclude the affection of instantaneous channel variation, the DIPA is designed to operate in large time scale (or super-frame) based...
Performance of next generation OFDM/OFDMA based Distributed Cellular Network (ODCN) where no cooperation based interference management schemes are used, is dependent on four major factors: 1) spectrum reuse factor, 2) number of sectors per site, 3) number of relay station per site and 4) modulation and coding efficiency achievable through link adaptation. The combined effect of these factors on the...
Since the using of OFDM in LTE system eliminates the inter-channel interference within cells, inter-cell interference has become the major influence factor of inter-cell resource allocation. Besides, with the increase of types of traffics, different QoS should be provided for different quality of services. A modified algorithm is proposed to ensure multi-traffic QoS by using rate conversion in allocation...
In fourth generation wireless communication standards, the throughput enhancement for cell edge users is a main issue so that various inter-cell interference (ICI) coordination techniques have been suggested. Since the coordination between different cells requires the resources of cooperating cell, its use should be determined carefully. In this paper, we consider two basic handover schemes (Fast...
This paper analyzes the problem of allocating power and subchannels in the downlink of a multi-cell, full-reuse OFDMA cellular system. We propose a distributed iterative algorithm, in which the allocation is performed independently in each cell, by maximizing the cell rate subject to a power constraint. The algorithm restricts the set of users that can be allocated on each subchannel, in order to...
We study a dynamic inter-cell interference coordination scheme formulated using a novel binary integer linear programming optimization technique. The scheme aims to maximize utility, where different utility measures have been defined to model varying levels of user fairness. The formulated problem is decomposed into a number of smaller sub-problems and solved iteratively to ease the computational...
This paper presents a framework based on self-organization to jointly self-optimize the spectrum assignment and the transmission power in the context of downlink OFDMA femtocell deployments. It is a distributed framework where each femtocell acts as an autonomous entity. Femtocells perform spectrum and transmission power assignment based on users' reported measurements, which are employed to sense...
The LTE-Advanced (LTE-A) system is currently under development to allow for significantly higher spectral efficiency and data throughput than LTE systems. In a wireless system based on orthogonal frequency division multiplexing (OFDM) with frequency reuse factor one such as LTE, the achievable cell spectral efficiency is often limited by the inter-cell interference or coverage shortage of base stations...
Reverse link (or uplink) performance of cellular systems is becoming increasingly important with the emergence of new uplink-bandwidth intensive applications such as Video Share, where end users upload video clips captured through their mobile devices. In particular, it is important to design the system to provide good user throughput in most of the coverage area, including at the cell edge. Soft...
Conventional zero-forcing precoding was well investigated, but it hadn't considered the channel quality indicator (CQI) mismatch for practical system with limited feedback. This paper studies a novel zero-forcing precoding with channel quality indicator (CQI) estimation and adjusting, channel directional information(CDI) quantization, user scheduling and link adaptation and then proposes a CQI estimation...
Multi-cell cooperative transmission schemes are considered as promising candidates in future 4G wireless networks (LTE-Advanced) to combat the inter-cell interference that degrades the cell-edge throughput performance. An efficient proportional fair (PF) scheduling algorithm for Orthogonal Frequency Division Multiple Access (OFDMA) based cooperative cellular networks is proposed. A PF metric maximization...
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