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In cognitive multimedia mesh networks (CMMNs), unlicensed users (secondary users, SUs) can share the spectrum with licensed users (primary users, PUs) on a non-interfering basis. The main challenge in CMMN is how to implement an efficient optimal control policy that can allocate spectrum and transmission powers for the SUs efficiently and how to adapt these resources to the changing network conditions...
We evaluate performance of hierarchical network (overlay-underlay cellular system) based on convolution method under mixed offered traffic. In most of the cases, different offered traffic of a network follows different probability density functions and they are correlated in sharing channel environment and cannot be analyzed by equivalent random theory (ERT) model. Here, three different types of offered...
In common models of cognitive radio networks (CRNs), priority in spectrum access of primary users (PUs) must be guaranteed, but the quality of service (QoS) for secondary users (SUs) is mostly ignored. Subject to meeting PUs' blocking probability objective, this paper proposes a channel reservation scheme to enhance QoS for SUs. The proposed scheme employs a centralized control manager (CCM) to coordinate...
This paper investigates the effects of adopting multiple transmission queues in IEEE 802.15.4 to differentiate frame sending priorities for providing QoS (Quality of Service) services. By employing different contention window operational parameters for various traffic classes like IEEE 802.11e, the multi-queue system can send frames of higher priority class more rapidly than those of the lower ones...
[Summary form only given]. As more and more low-cost high-quality devices appear on the market and new applications emerge every day, short-range wireless personal area networks (WPANs), both low and high-data-rate, are on the horizon. Two major efforts of IEEE are underway to enhance the development of WPANs. One is the specification of IEEE 802.15.3a, also known as ultra wideband (UWB), used in...
Low utilization efficiency of spectrum, which is caused by fixed spectrum allocation scheme, is the bottleneck of wireless communication systems. Cognitive Radio (CR) is proposed to utilize the idle spectrum in an intelligent way while not interfering with primary users. For application of CR, the objective is the optimization of spectrum utilization. In order to achieve this, we propose a multi-channel...
With the IEEE 802.16e standard for mobile WiMAX the course for new 4G mobile radio communication systems is set. It offers significantly higher data rates than GSM or WCDMA/UMTS and supports different handover mechanisms and QoS features in contrast to WiFi (IEEE 802.11 g) on the OSI-layer 2 (L2). Since WiMAX-devices are hardly available today and protocol optimizations are strongly restricted with...
IEEE 802.16 wireless networks, known as WiMAX, employ a mechanism for guaranteed time allocation to mobile stations in order to meet the different quality of service requirements for service flows. The base station allocates contention-based time slots for the stations to transmit their requests for additional bandwidth. Each contention time slot can accommodate a single transmission if there is no...
Wireless distributed systems (WDS) for IEEE 802.11 WLANs are gaining popularity as an effective mean to extend the network coverage area. However, the use of just one wireless channel restricts their efficiency. In this paper, we propose to use a multi-interface WDS to enhance its performance. We investigate two different scheduling policies the sequencing enforced policy (SEP) and the sequencing...
In this paper, we propose an analytical model to evaluate performances of a wireless network composed by two groups of nodes using two different backoff schemes for channel access. The two different backoff schemes are used for QoS differentiation in term of priority. Our analysis results show that the priority group can have its performances enhanced, in term of saturation throughput and delay, without...
In this paper, we present a new effective mathematical analysis to numerically evaluate the performance for multi- traffic in wireless communication networks with multi-channel and an admission control scheme. We apply a matrix geometric solution method to describe the stochastic behavior of the system and give the exact performance measures, such as, utilization of channel for both voice and data...
Wireless local area networks (WLANs) are increasingly popular because of their flexibility. This spreading of WLANs comes with an increasing use of multimedia applications. Such applications are bandwidth sensitive and require a quality of service (QoS) that guarantees high performance transmission of continuous data. This requirement is the focus of the new enhanced IEEE 802.11e standard protocol...
The main benefit of vehicular communication is seen in active safety systems that increase passenger safety by exchanging warning messages between vehicles. Other applications and private services are also permitted in order to lower the cost and to encourage vehicular network deployment and adoption. The allocation of 75 MHz in the 5.9 GHz frequency band licensed for dedicated short range communications...
In this paper performance of dynamic bandwidth allocation in broadband wireless networks under dynamic arrival process and channel SNR is evaluated using queuing analysis framework. Adaptive modulation and coding rate based on IEEE 802.16 standard is used to adjust the transmission rate adaptively in each frame time according to channel quality in order to obtain multi-user diversity gain. Arrival...
IEEE 802. lie has a new coordination function, which has both contention-based and contention-free medium access methods, in order to support applications with Quality of Service (QoS) requirements. The contention-based MAC protocol, Enhanced Distributed Channel Access (EDCA) supports QoS; however, it cannot guarantee strict QoS required by real-time applications without proper tuning of QoS parameters...
The Ad hoc On Demand Distance Vector (AODV) routing protocol is intended for use by mobile nodes in ad hoc networks. To provide quality of service, extensions can be added to the messages used during route discovery. These extensions specify the service requirements which must be met by nodes rebroadcasting a route request (RREQ) or returning a route reply (RREP) for a destination. In order to provide...
Release99 of UMTS (universal mobile telecommunication system) network supports conversational services by means of UTRAN (universal terrestrial radio access network) dedicated transport channels (DCH). In this paper we evaluate by means of dynamic simulations the impacts of the radio access network on the end-to-end quality of service (QoS) of voice over IP (VoIP). In order to characterize the QoS...
This paper proposes a fast forward medium access control protocol (FFMAC) for quality-of-service (QoS) guarantee in multihop IEEE 802.11s wireless mesh networks with multiple channels. To the best of our knowledge, the proposed protocol is the first one which considers the multihop and multichannel issues simultaneously. It provides higher priority for real-time applications, while remaining the distributed...
In this paper, we propose multi-channel time division multiple access (MC/TDMA) scheme which provides proportional service differentiation while achieving high throughput in a multichannel wireless network. Proportional service differentiation is achieved by scheduling traffic over multiple non- overlapping channels using the modified open-shop scheduling problem analogy. This analogy allows us to...
The next step in the evolution of UMTS is the Enhanced Uplink or high speed uplink packet access (HSUPA), which is designed for the efficient transport of packet switched data. One of the major novelties is the relocation of the scheduling control from the RNC to the NodeB which enables a faster reaction to cell load and radio condition variations. Our contribution is an analytic modelling approach...
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