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Most mobile communication systems deployed use 3-fold sectorization with directed antennas to avoid inter-sector interference and to spatially reuse available radio resources. However, innovations in next generation networks such as multiple antenna systems and coordinated multi-point techniques allow mitigation or even exploitation of interference. In this paper, we discuss how sectorization and...
We develop an interference alignment (IA) technique for a downlink cellular system. In the uplink, IA schemes need channel-state-information exchange across base-stations of different cells, but our downlink IA technique requires feedback only within a cell. As a result, the proposed scheme can be implemented with minimal changes to an existing cellular system where the feedback mechanism (within...
In this paper, we investigate the capacity of wireless hybrid networks, in which a wired network of base stations is used to support long-range communications between wireless nodes. We introduce the multiple access technique by allowing more than one source node to transmit simultaneously and utilizing successive interference cancellation to decode information at the destination node. Our results...
The Wyner model has been widely used to model and analyze cellular networks due to its simplicity and analytical tractability. The key aspects of this model are fixed user location and deterministic and homogeneous interference intensity. While clearly a significant simplification of a real cellular system, which has random user locations and interference levels that can vary by several orders of...
In this paper a novel framework for extending QoS to QoE in wireless networks is introduced. Instead of viewing QoE as an off-line apriori mapping between users' subjective perspective of their service quality and specific networking metrics, we treat QoE provisioning as a dynamic process that enables users to express their preference with respect to the instantaneous experience of their service performance,...
Frequency-domain scheduling and rate adaptation have helped next generation orthogonal frequency division multiple access (OFDMA) based wireless cellular systems such as Long Term Evolution (LTE) achieve significantly higher spectral efficiencies. To overcome the severe uplink feedback bandwidth constraints, LTE uses several techniques to reduce the feedback required by a frequency-domain scheduler...
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,...
In this paper, we propose a distributed adaptive interference coordination algorithm for a practical orthogonal frequency division multiple access (OFDMA)-based mobile cellular systems. The designed algorithm can achieve an efficient frequency reuse for any user distribution and traffic load. Since no a priori frequency planning is required, the minimal coordination between base stations is also achieved...
Client relay is a promising technology to improve the performance of the cell-edge clients in a wireless cellular network. Unfortunately, there is a lack of performance analysis results for client relay networks in the research literature. This is mainly due to extremely complex interactions between network, data link and physical layers. In this paper we fill in this gap by proposing several techniques...
This paper considers a relay-assisted bidirectional cellular network where the base station (BS) communicates with each mobile station (MS) using orthogonal frequency-division multiple-access (OFDMA) for both uplink and downlink. We first introduce a novel three-time-slot time-division duplexing (TDD) transmission protocol. This protocol unifies the direct transmission, one-way relaying and network-coded...
There has been a lot of recent interest in the potential of inter-base station cooperation techniques to manage excessive out-of-cell interference in evolving cellular networks. In this paper, we propose and describe a signal processing approach based on a novel Network Interference Cancellation Engine (NICE), which opportunistically cancels dominant out-of-cell interference by exchanging decoded...
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...
Uplink scheduling in a multicell OFDMA system is considered. A non-collaborative intercell interference avoidance method is proposed, where base stations shut down certain subcarriers in a probabilistic manner based on the received interference level. Proportional fair scheduling is implemented in order to ensure fairness for cell edge users. A low complexity scheduling algorithm is proposed for this...
In this paper we deal with the role and the importance of Radio Resource Management (RRM) in cellular networks from an economic point of view. Among the main economic aspects which can influence the network operation, we can point out price models, consumer behavior and the competition among cellular operators. Our focus, however, is on the particular link between customer satisfaction, customer retention,...
A novel coordinated scheduling algorithm for OFDM-based systems in multi-cell scenario is proposed in this paper. The studied algorithm based on the utility function is general for the downlink of networks. The algorithm coordinates the subcarrier assignment over the BS cluster. We first establish the framework for this inter-cell coordinated optimization problem through utility-based method. The...
Optimizing the network performance is a key objective for cellular operators as over-provisioning a network is definitely not a cost-effective solution. However the trend for the upcoming 4G networks is to simplify the planning procedure and to improve the spectral efficiency by using agressive frequency reuse schemes, e.g reuse-1, in the downlink. In this paper, we show that this is not a suitable...
Research conducted at Morgan State University (MSU) has proposed a new approach for modeling and managing Quality of Service (QoS) in a cellular and ad-hoc mixed wireless network. This paper focuses on two key areas. It first introduces the “power” performance measure to model and manage the QoS requirements for wireless nodes with time critical applications as a function of the traffic level. It...
Energy consumption is lately receiving increased interest, and research efforts to assess the energy efficiency of cellular communication networks are made. This paper addresses the tradeoffs between gains in cell throughput that can be expected from coordinated multi point transmission and reception technologies and the increased energy consumption that they induce in cellular base stations. We explicitly...
This paper investigates the uplink throughput of network MIMO cellular systems at low signal-to-noise ratio (SNR). The network is modeled according to Wyner's extended cellular model, with intracell orthogonal medium access control. We derive analytical expressions for the two key low SNR parameters; namely, the minimum required Eb/N0 for reliable communications and the wideband slope, assuming noncooperative...
Two fundamental problems in any cellular systems are limited capacity and the presence of unbalanced traffic. In this paper, we propose a novel grouping infrastructure for next generation cellular networks, whose objective is to increase the system throughput and further improve the system balance. In the cellular system, we consider all the available users are divided into two groups. One is the...
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