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Security has grown to be a major concern in regulate to provide restricted communication in Wireless as well as wired environment. As far as security concern related to WiMAX network i.e for PHY Layer (Jamming and scrambling) and MAC Layer attack protection has been provided by (AES, PKM etc) one separate Layer(Security Layer). In current scenario Network Layer security is more vital and we have analyzed...
OFDMA has emerged as a promising physical layer technology for LTE wireless networks. OFDM solves the problem of co-channel interference in intra-cell to some extent because of the orthogonality of subcarriers, along with the character of guard interval and cyclic prefix. However, inter-cell interference still exists, especially the cell edge users suffer from interferences seriously, which leads...
The fast pace of development of telecommunications technology and the challenges presented with the increasing number of users for any service, anywhere, anytime, access creates new problems with on the base stations capability and the handover/handoff (HO) techniques. To face these challenges much research have been made to come out with algorithms that can handle handover of user equipment (UE)...
In the OFDMA-based cellular relay networks, relay selection and resource allocation are the main problem to be solved. Many present works about resource allocation are for the goal of throughput maximization. In this paper, we propose an adaptive resources allocation algorithm joint relay selection, sub-carrier assignment and power allocation for the goal of energy saving to ensure users' QoS, and...
The future airport surface communication system, called AeroMACS, shall be based on the IEEE 802.16 standard, in particular on the "WiMAX Mobile System Profile Specification". In the course of the SANDRA project the IEEE standard and the WIMAX mobile profile have been investigated and different configuration options have been evaluated. This paper presents an overview of options related...
One of the fundamental requirements of state-of-the-art and next-generation OFDMA-based wireless communication systems is the provision of quality of service (QoS) guarantees. This paper addresses the design of cross-layer channel-and queue-aware scheduling and resource allocation algorithms jointly assigning transmission data rates, bandwidth and/or power to active users while providing support to...
This paper presents new energy-aware QoS scheduling and call admission control algorithms for WiMAX IEEE 802.16e broadband wireless access standard. The scheduling algorithm works at MAC layer and is designed towards minimizing power consumption at mobile stations supporting multiple UGS connections, while meeting the QoS requirements of the connections. The scheduling algorithm uses a novel idea...
To efficiently utilize the advantages of orthogonal-frequency-division-multiplexing (OFDM) and wireless relay techniques, we propose the resource allocation schemes with statistical quality-of-service (QoS) guarantees for the wireless OFDM amplify-and-forward (AF) relay system in this paper. Firstly, we formulate the resource allocation problems for the wireless OFDM AF relay system with QoS guarantees...
In this paper, a 2-Dimension (2-D) resource allocation problem for energy efficiency maximization in the uplink of an OFDMA network is studied. Firstly, with the metric of energy efficiency, measured as bits-per-joule, we convert the complex problem of optimizing the system energy efficiency, defined as sum of users' bits-per-joule, into an optimal achievable rate comparison problem, and devise a...
We propose an efficient resource allocation scheme for OFDMA based femtocells networks under imperfect channel knowledge. Several femtocell users share the same spectrum but no interference exists between each other. The transmit power of femtocell users is minimized under the users' QoS constraints. Based on the interference channel model of femtocell users, an accurate interference estimation approach...
Femtocells can offload the traffic of macrocells and satisfy the big high-data-rate wireless communication requirement of indoor users. Due to the large number of fmetocells deployed by users, a significant challenge this new access technology brings to us is coordinating the cross-tier interference. Much special attention has been paid to solve the problem. This paper presents a novel strategy to...
Multiuser OFDM (MU-OFDM) is widely applied nowadays to provide diverse Quality of Service (QoS) for multiple users. Subcarrier allocation according to the instantaneous channel state information (CSI) in MU-OFDM system has been well studied while the research of allocating subcarriers to each user constrained by diverse QoS requirements still remains large space undisclosed. In this paper, in order...
IEEE 802.11p hardware is hard to find. Previous research efforts often relied on project-specific prototype implementations which are characterized by a high cost and are not always available to the entire research community. Commercially available turnkey implementations are rare and quite expensive compared to commercial of-the-shelf (COTS) IEEE 802.11a/b/g hardware. However, the difference between...
Besides avoiding inter-symbol interference and leading to high capacity, wireless orthogonal frequency division multiplexing (OFDM) provide fine granularity for resource allocation since they are capable of dynamically assigning sub-carriers to multiple users and adaptively allocating transmit power. The current dominate layered networking architecture, in which each layer is designed and operated...
Long Term Evolution (LTE) is considered one of the main candidate to provide wireless broadband access to mobile users. Among main LTE characteristics, flexibility and efficiency can be guaranteed by resorting to suitable resource allocation schemes, in particular by adopting adaptive OFDM schemes. This paper proposes a novel solution to the sub-carrier allocation problem for the LTE downlink that...
LTE system performance largely depends on the high efficiency of frequency domain resource scheduling. This paper presents a single-cell LTE Downlink scheduling model, and then introduces the economic concept of utility function in order to design a LTE system scheduling algorithm based on the utility function (UBS) and we simulate the algorithm. We simulate and compare throughput, fairness, packet...
Since the IEEE 802.16 first standard was proposed in 2004 to provide broadband wireless service, the standard has not only been widely studied, but also broadly commercialized. The current IEEE 802.16-2009 standard document specifies five Quality of Service classes. As is typical with most standards, IEEE 802.16 does not require the use of a specific scheduler. In this paper, we first evaluate the...
In this paper, we consider the group oriented beamforming taking into account the quality of service (QoS) requirement for multimedia applications in multiuser/multi-rate OFDM system. The aim of this paper is to find the scheme for maximizing the system throughput while guarantee the QoS requirements and fairness for all services. The simulation result indicates that this scheme proposed in this paper...
The following topics are dealt with: wireless communications and networking WCN/WLAN/WiMAX; optical communications and networking OCN; mobile communications/wireless/mobility; mobile ad-hoc and sensor mesh networks; network management and services; UWD/RFID/OFDM and Nano/Bio, and; quality of service, traffic management and dynamic spectrum access networks.
A novel adaptive Orthogonal Frequency-Division Multiplexing (OFDM) system with multi-layered (ML) transmission is proposed for mobile multimedia networks to support transmission of multiple data streams with flexible Quality-of-Service (QoS) adjustment capability and therefore can accommodate users with different QoS requirements or link conditions. The enhanced layers (ELs), formulated by parallel...
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