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We formulate the resource allocation in the downlink of heterogeneous orthogonal frequency division multiple access (OFDMA) networks. Our primary objective is to maximize the system sum throughput subject to service and system constraints, including maximum transmit power, quality of service and per-user subchannel allocation. Due to the intercell interference, the corresponding optimization problem...
In this paper, we address the energy efficient resource allocation problem for a secure orthogonal frequency division multiple access (OFDMA) relay system. In particular, we consider there is a eavesdropper near the base station (BS) which tries to overtake the information sent by BS. We formulate the joint optimization problem with the objective to optimize the energy efficiency of the considered...
This paper proposes a selective AF-OFDM (Amplify-and-Forward, Orthogonal Frequency Division Multiplexing) relaying protocol, in which selective relaying policy is adequately utilized to improve the spectrum efficiency of cooperative multi-carrier transmission, and addresses the power minimization problem subject to a target quality of service (QoS) constraint for corresponding battery-operated systems...
It is envisaged that there will be heterogeneous deployment of ultra-dense femtocells overlaying the existing macrocells in an ad-hoc manner to provide enhanced coverage and capacity for the indoor users in the fifth generation (5G) wireless networks. However, this will lead to serious interference between macrocells and femtocells (cross-tier interference) and interference between neighbouring femtocells...
In today's world energy efficiency in wireless communication becomes vital topic in Telecommunication industry and also to create eco-friendly atmosphere we want green communication. Additionally, the data traffic is also a lot among users. Thus, we are considering energy efficient and QoS together for users. In our scheme, energy efficient radio and resource allocation for long term Evolution (LTE)...
In this paper, an adjacent maximized channel load (ADCL) assignment scheme is proposed for the downlink of multi-rate MC-DS-CDMA with improved capacity utilization while maintaining the demand of quality of service (QoS). The ADCL scheme assigns new call request to a vacant code which leads to minimum new blocking of higher rate calls. The code selection algorithm first of all selects those codes...
Cellular phones play an important part in modern day life. At present it's very uncommon to see a person without using mobile phones. Due to Increasing mobile users across globe, rising trend of multifloor and intricate designed apartments in inner-city area, poor coverage found as a key issue. To surmount this femtocell allows service providers to extend service coverage inside of home — especially...
In this paper we consider the link adaptation problem per Secondary User when adopting orthogonal frequency division multiplexing (OFDM)-based cognitive radio networks. The main issue herein is to provide a high Quality of Service (QoS) to SUs, while tolerating that the mutual interference between this latter and the primary user (PU) persists within a given range. To address this constrained problem,...
Long Term Evolution (LTE) is one of the standards in 4G cellular technologies which offer different data rates for voice, video conference and other services. The Orthogonal Frequency Division Multiple Access (OFDMA) is a well suited multiple access scheme of LTE for supporting variable bit rate services. OFDMA-based Cellular communication network face serious challenges in providing good Quality...
LTE is the next step of the broadband cellular technology evolution. It is referred as the fourth generation (4G) technology which offers better performance in throughput, latency, and spectral efficiency. It uses OFDM that is proven to combat inter-symbol-interference (ISI), multipath fading, and enabling scalable bandwidth allocation. Downlink LTE uses OFDM technology variation called OFDMA which...
In this paper we compare three novel schemes for dynamic frequency allocation and transmission power assignment for cognitive radio networks. These spectrum allocation schemes are based on reinforcement learning and power optimization procedures. We propose the so-called RL+Power and RL+Power Coupled schemes and compare them with an existing constant power scheme. Simulation results show that the...
The paper presents results of an investigation of a MU-MIMO system suitable for providing broadband services. The base station has a circular array and each user has a single high gain antenna. Two optimum zero forcing beamformers are considered and semi-orthogonal user selection is used to schedule users in the downlink. A key point of the investigation is to determine the maximum number of users...
The increasing demand for data and multimedia services, as well as the ubiquitous nature of the current generation of mobile devices have resulted in continuous network upgrades to support an ever-increasing number of users. However, given that wireless communication systems operate on radiofrequency waves, the health effects of electromagnetic (EM) emission from these systems are increasingly becoming...
Method of balancing the number of subchannels allocated to subscriber stations in WiMAX network based on solution of optimization problem associated with maximizing the lower level allocated bandwidth for each subscriber station according to its QoS requirements for access rate was investigated. Research of proposed method confirmed the adequacy of the model and effectiveness of solutions as a whole...
The special communication scenario in High-Speed Train (HST) not only leads to an increasing demand of high throughput and continuous multimedia services but also arises many other challenges for cellular network access technology, such as high mobility, frequent and group handovers etc. In order to address above problems, we propose an HST WiFi network application scheme which adopts multi-hop technology...
Orthogonal frequency division multiple access (OFDMA) is an effective method to reduce inter symbol interference in LTE systems. Doppler shift, however, leads to a loss of sub-channel orthogonality, resulting in inter-channel interference in high speed environment. Firstly, this paper develops the mathematical formulae describing the interference on resource block (RB) which is the smallest resource...
In this paper, we propose a low-complexity quality of service (QoS)-oriented resource and power allocation framework. The aim of our scheme is to adjust the power expenditure of mobile stations (MSs) according to their QoS demands, which are imposed by the applications on the MS ranging from conversational and video-conference to telemetry and bulk data, for instance. Users are scheduled based on...
We study the energy-optimal subcarrier power allocation for OFDM-based cognitive radio (CR) networks. A CR transmitter communicates with CR receivers on a channel borrowed from licensed primary users (PUs) when PUs' transmission are detected absence on those channels. Due to non-orthogonality of the transmitted signals in the adjacent bands, both the PU and the secondary user (SU) cause mutual-interference...
This paper presents a new cross-layer (PHY/MAC) resource allocation scheme based on Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiple Access (OFDMA) system with a multi-service (MS) and a multiuser (MU) configuration. It is about a downlink transmission chain based on the IEEE 802.16m specifications, in which the available resources (power and bandwidth) are dynamically...
At present, the user experience provided by smart mobile terminals is limited to the battery capacity. This paper focuses on how to improve the energy efficiency of terminals in OFDMA-based wireless multicast systems with frequency-selective channels. We assume that multicast terminals can switch to sleep mode during the transmission of some OFDM symbols according to their OFDMA frame-level quality...
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