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In this paper, we address the energy conservation problem with the quality of service (QoS) requirements taken into account for the physical downlink shared channel (PDSCH) in LTE/LTE-Advanced networks. By jointly allocating the modulation and coding schemes (MCS), resource blocks (RB), and power, we first propose a standards-compliant QoS-oriented power control algorithm (SQPC) for realistic systems...
Physical layer network coding (PNC) has recently attracted attention in wireless relay system. With PNC, the destructive effect of interference in wireless networks can be eliminated and the capacity of networks can be boosted significantly. However, synchronization is always considered as an outstanding issue which causes performance penalty on PNC. In [7], the impact of imperfect synchronization...
In this paper, cooperative positioning for Long Term Evolution (LTE) cellular systems using Radio Frequency Pattern Matching (RFPM) is studied. Having the locations of users in a cellular system supports many applications such as location-based services and E911. Although Global Positioning System (GPS) can be found in every smartphone, its poor performance in indoor and dense environments encourages...
Narrowband interference (NBI) is a known problem in wireless communications. However, analyses found in the NBI literature often model the signal of interest as a generic transport channel with all subcarriers conveying information of the same kind, e.g. user plane data. By taking the analysis down to physical channels' level, this paper aims to obtain a deeper understanding of the impact exerted...
In 3GPP Release-12 specification, the adoption of small cells in long term evolution (LTE) networks is considered as a promising solution to meet the growing traffic demand for mobile data usage. However, energy consumption becomes a crucial challenge for network operators to deploy more small cells in heterogeneous networks in order to fulfill the requirement for achieving high data rates. In this...
Resource reuse among heterogeneous cells in LTE-A networks permits to increase the spectral efficiency but requires suitable interference mitigation techniques. Among these Coordinated scheduling and beamforming (CS/CB) is a promising solution. This paper proposes a new CS/CB scheme aiming to maximizing the mean system throughput taking into account the fairness among the cells. First the most suitable...
In this paper, by jointly considering subchannels, power, and Modulation and Coding Scheme (MCS) allocation, we address the sum-rate maximization problem in OFDMA downlink systems. We formulate the problem as an integer linear programming (ILP), which maximizes the system sum-rate subject to the minimum rate requirements of users and total transmit power constraint of base station. To solve the formulation...
In macro and Closed Subscriber Group (CSG) femtocells co-channel deployment, femtocells and Macrocell User Equipments (MUEs) suffer strong interference from neighboring femtocells. The interference seriously degrades MUEs' throughput performance or even causes outage. To solve this issue, we provide a centralized component carrier selection scheme. By globally optimizing femtocells' and MUEs' component...
In this paper, the multi-channel performance of large scale deployment of Long Term Evolution (LTE) in Unlicensed (LTE-U) band and WiFi using stochastic geometry is studied. LTE-U and WiFi cell placement is modeled as a Poisson Point Process (PPP), while transmission activity is modeled as hardcore simple sequential inhibition (SSI) point processes, which have been shown to accurately model Carrier...
The increasing needs of mobile internet application services running on smartphone is driving the evolution of wireless communication networks, due to the diversity of traffic characteristics in addition to the rapid growth of data volumes. Differently from typical internet services like web browsing and FTP, the pervasive usage of always-on applications can lead to frequent User Equipment (UE) transitions...
In this paper, we propose a dynamic decentralized scheme, namely, the Multi-Objective Harmony Search (MO-HS). The proposed scheme improves on the conventional single-objective HS scheme by attempting to optimize two objective functions simultaneously. In particular, the MO-HS scheme attempts to minimize the use of the same channels by edge users in neighboring cells, and the average cell interference...
This paper presents an energy efficient relay deployment algorithm that determines the optimal location and number of relays for future wireless networks, including Long Term Evolution (LTE)-Advanced heterogeneous networks. We formulate an energy minimization problem for macro-relay heterogeneous networks as a Mixed Integer Linear Programming (MILP) problem. The proposed algorithm not only optimally...
Recently there has been a great interest in how to apply Long Term Evolution (LTE) in Professional Mobile Radio (PMR) context, which is used for public safety work. However, LTE is not yet optimized for low bit rate voice communication. The smallest LTE packet size is still too large in case that low bit rate voice communication is transmitted in high quality channel. This is one of the main challenges...
In this article we discuss a case of a cellular network with backhaul operated wirelessly on millimeter waves (mmWaves). We perform extensive studies based on ray-tracing and system-level simulations to assess performance of such deployments. For the purpose of the evaluations we propose a backhaul topology optimization algorithm that allows assessment of the gateway (GW), i.e. nodes with wired backhaul,...
Due to the joint evolution of mobile applications and cloud services, mobile users routinely act as both content consumers and producers. Nowadays there is an increasing trend in both the downlink (DL) and uplink (UL) data traffic, which are predominantly Transmission Control Protocol (TCP) based. Simultaneous DL and UL TCP transmission over an asymmetric link causes significant throughput degradation...
Serving online applications and commercial web sites with low latency is business critical. As content requests originate from geographically distant locations and increasingly from mobile devices, globally ensuring service quality is challenging. The content is delivered to the clients predominantly via the Transmission Control Protocol (TCP), therefore optimal TCP operation over radio access is...
Urban (and suburban) informal settlements in emerging markets will be the fastest growing population hotspots in the next few decades. This presents a significant challenge in delivery of services, including affordable mobile Internet access. Operator-led upgrades through network densification (rollout of additional operator-maintained sites) are difficult to sustain in those areas due to low revenues,...
Network densification with small cells has been recognized as the key mechanism in addressing the unremitting traffic growth over the next decade. This hierarchical network paradigm is characterized by highly fluctuating traffic demand, vast amount of signaling exchange, as well as progressively intensified resource under-utilization owing to service asymmetry. A flexible backhaul framework is imperative...
Carrier Aggregation (CA) is one of the promising techniques to support the wider bandwidth and fulfil the higher data rate requirement in LTE-Advanced system. Combined with Cognitive Radio (CR), the packet scheduler is more intelligent to assign the radio resources dynamically. To the best of our knowledge, Carrier Scheduling (CS) scheme in the cognitive LTE-A system with CA has not thoroughly been...
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