Multimedia Traffic

The Integrated Broadcast Interaction System is implemented with a fully regenerative On-Board Processor (Alcatel 9343) designed to provide direct (distributed) DVB-RCS[1] (Digital Video Broadcasting Return Channel Satellite) compliant satellite access for individual digital video broadcasters, Internet Service Providers, and multimedia users. This paper presents the mechanisms which make it possible to support connectionless services over a connection oriented satellite network as well as provide QoS support.

Because of bursty high data rate and delay sensitive nature of high quality multimedia application, the resource allocation in wireless network to meet its quality of service (QoS) has become the most challenging and interesting issue. Orthogonal Frequency Division Multiple Access (OFDMA) employing adaptive channel allocation technique can support these requirement while increasing the system capacity many fold. Here, an efficient resource allocation method called two stage rate adaptive (TSRA) ...

This document proposes an informal management model of Differentiated Services (Diffserv) routers for use in their management and configuration. This model defines functional datapath elements (e.g., classifiers, meters, actions, marking, absolute dropping, counting, multiplexing), algorithmic droppers, queues and schedulers. It describes possible configuration parameters for these elements and how they might be interconnected to realize the range of traffic conditioning and per-hop behavior (PHB) functionalities described in the Diffserv Architecture.

We develop scheduling strategies for carrying multimedia traffic over a polled multiple access wireless network with fading. We consider a slotted system with three classes of traffic (voice, streaming media and file transfers). A Markov model is used for the fading and also for modeling voice packet arrivals and streaming arrivals. The performance objectives are a loss probability for voice, mean network delay for streaming media, and time average throughput for file transfers. A central scheduler (e.g., the access point in a single cell IEEE 802.11 wireless local area network (WLAN)) is assumed to be able to keep track of all the available state information and make the scheduling decision in each slot (e.g., as would be the case for PCF mode operation of the IEEE 802.11 WLAN). The problem is modeled as a constrained Markov decision problem. By using constraint relaxations (a linear relaxation and Whittle type relaxations) an index based policy is obtained. For the file transfers the decision problem turns out to be one with partial state information. Numerical comparisons are provided with the performance obtained from some simple policies.

In this work we study the problem of QoS routing under inaccurate link state. In particular we compare the efficiency of different link cost functions in a realistic environment where the link state changes are not immediately communicated to all the nodes in the network. We also analyse the effects of predicting the present network state when a node must make a routing decision. For this purpose, we consider an optimistic and a pessimistic prediction, together with a combination of these two assumptions through a multi-path search policy.

Radio channel allocation is broadly studied in the framework of cellular networks. Channels are scarce resources and to be utilised judiciously by the cells of the network. During the course of channel allocation, channels are normally lent/borrowed to the neighbour cells. Most of the available channel allocation techniques apply only single lending/borrowing. With the emergence of cognitive radio, it has now become possible to utilise the channels opportunistically. Availing the channels are the services which are normally categorised into realtime and non-real-time services. Of these, real-time services are given more priority to serve over the non-real-time services. Further, among the new call and handoff services, the latter are given priority to serve. This work proposes a novel heuristic approach for better channel utilisation for these services, blending the idea of cognitive radio and multi-channel lending/borrowing. The performance study, of the proposed model, is done by simulation which reveals the effective channel utilisation in terms of blocked and dropped services.

Wireless Local Area Networks (WLANs) supporting modern streaming multimedia applications constitute a very challenging and rapidly changing field of research. Towards implementing effective multimedia wireless networks, the IEEE has published the "state of the art" IEEE 802.11e standard, which introduced a QoS-aware MAC-layer along with a series of efficiency enhancements. However, it has been proven inadequate in handling multimedia traffic optimally in periods of congestion. For the efficient support of multimedia applications in high load situations, numerous mechanisms have emerged, most of them focusing on altering the static nature of resource allocation specified in IEEE 802.11e. Nevertheless, traffic characteristics must be taken into consideration in order to achieve the highest gains. In this paper, an application-aware MAC-layer mechanism is developed that exploits multimedia frame semantics and existing MAC-layer enhancements to adequately cope with high congestion situations in IEEE 802.11e infrastructure networks. The proposed algorithm makes use of existing acknowledgment policies and adaptive resource allocation techniques depending on multimedia frame significance. The effectiveness of the algorithm is proven by means of simulations, where its functionality is evaluated and compared with other existing schemes.

In an ATM Customer Premises Network, there is ahantage in having shared access across the one Broadband User Network Interface (UNI). In this paper, we consider ATM shared access issues based on the GFC protocols as network support for multimedia communications, and we propose a mechanism for shared-medium access to an ATWB-ISDN network to support multimedia traffic. The access scheme proposed is based on direct access to a slotted medium on ring network. By installing insertion buffers at each station reduces media access time, and using spatial reuse by destination release procedure increases the throughput. The proposed Reset-Window with Buffer Insertion Protocol (RBI) includes multiple prioritized access to be able to transport multimedia communications. This access protocol is described and its performance is analyzed. The mean cell access delay and the fair sharing of the non-guaranteed bandwidth are evaluated by a simulation.

nPoA nPoA BTS B BTS C BTS D Administrative Domain B Corresponding Host IP ch N2 Configuration Agent Authentication h/o delay 900 ms 802.11 802.11 4 Seconds media interruption h/o delay 4 s Handoff Delay ~ 18 s 802.11 CDMA 18 Seconds media interruption h/o delay 18 s Key advantages: Key advantages: 1)Provides the ability to discover the network elements prior to handover without relying on underlying layer 2 discovery mechanism after the handover 2) eliminates layer 2 scanning delay during handover by caching the channel number

A novel interleaved polling algorithm for Long-Reach EPONs is proposed in order to simultaneously provide subscriber and class of service differentiation. It is demonstrated that the new polling algorithm applied to a typical 100 km Long-Reach EPON performs better than centralized methods, where bandwidth prediction is needed to overcome the higher round trip time in which ONUs cannot transmit. As polling methods in Long-Reach EPONs do not require prediction, they are much simpler and show less computational complexity than centralized schemes, avoiding the inaccuracy of bandwidth prediction. Simulation results show that the new algorithm increases the achieved throughput when compared to centralized algorithms with traffic prediction, obtaining a significant reduction of both mean packet delay and packet loss ratio for the highest priority service level profiles.

With the ever increasing demand of multimedia traffic on the internet the interest in deploying multicast has increased. One hurdle in this regard is quantifying the multicast protocol performance. Many efforts have been put into defining multicast metrics for evaluating protocol performance. In this paper we identified metrics that will provide reasonable measure of protocol's efficiency. The metric is developed keeping two perspectives in mind. First, how efficient a multicast protocol is in utilizing network resources and second, the quality of service it can provide to the end user. A simulation was done using ns-2 to evaluate the performance of multicast protocols based on the metrics we identified. The overall performance of each protocol is calculated and relative efficiency of each protocol is established based on our metrics.

DVB-RCS synchronization scheme on the Return Channel requires the RCSTs to be programmed with their location coordinates with an accuracy of no more than a few kilometers. RCSTs use this location information in their ranging calculation to the servicing satellite. For certain users this location information disclosure to the network operator can be seen as a serious security event. Recent work of the authors overcame this requirement by cloaking the location of an RCST in such a way (based on "spatial/geometric" symmetries of the network) that the respective ranging calculations are not affected. In this work we argue that timing tolerances in the Return Channel synchronization scheme, accepted by the DVB-RCS standard, can be used in combination to the "spatial" method, further enhancing the location privacy of an RCST. Theoretical findings of the proposed "spatial-timing" approach were used to develop a practical method that can be used by workers in t...

This paper introduces a new approach to integrate different types of medium access control (MAC) protocols into a single wavelength-division-multiplexing (WDM) network system. The WDM network is based on a passive star coupler, and the purpose of integrating different MAC protocols is to efficiently accommodate various types of multimedia traffic streams with different characteristics and quality of service demands. Our integrated MAC protocol is termed multimedia wavelength-division multiple-access (M-WDMA). Three types of multimedia traffic streams are considered in this paper: constant-bit-rate traffic and two classes of variable-bit-rate traffic. Accordingly, three tunable transmitters and one fixed home channel receiver are used in the design of each WDM node. The transmitters transmit the three types of multimedia traffic streams in a pipeline fashion so as to overcome the tuning time overhead and to support parallel transmissions of traffic streams that emerge simultaneously. We further incorporate a dynamic bandwidth allocation scheme that dynamically adjusts the portions of bandwidth occupied by the three types of traffic streams according to their demands. Consequently the M-WDMA protocol achieves high utilization and efficiently adapts to the demands of the multimedia streams so as to guarantee their QoS. The performance of the M-WDMA is evaluated through a simple analytical model and extensive discrete-event simulations. It is shown that the M-WDMA can satisfy the QoS requirements of various mixes of multimedia traffic streams even under very stringent requirements. Moreover, we show that the M-WDMA outperforms conventional MAC protocols for WDM networks. As a result, we expect M-WDMA to be a good multimedia MAC candidate protocol for future-generation WDM networks.

In this paper, the performance enhancement algorithm of channel allocation for voice and data transmission in cellular networks is proposed. The voice activity detection has been applied to dynamic channel allocation procedure to detect and separate the silence and speech among conversation periods. Hence a data user can use the silent period of an active voice channel to transmit its information. To control the selecting of channel allocation policies, the information of number of data in transmission waiting queue has been determined in order to accept the performance measurement. In the simulation results, the improvement of the performance shows via the quality of services, which are an average delay in queue, a blocking probability, and an impact of the proposed scheme is presented in the system.

Because of bursty high data rate and delay sensitive nature of high quality multimedia application, the resource allocation in wireless network to meet its quality of service (QoS) has become the most challenging and interesting issue. Orthogonal Frequency Division Multiple Access (OFDMA) employing adaptive channel allocation technique can support these requirement while increasing the system capacity many fold. Here, an efficient resource allocation method called two stage rate adaptive (TSRA) ...

Traffic control and resource management are complex issues in wireless asynchronous transfer mode (WATM) due to broad range quality-of-services (QoS), limited bandwidth spectrum and susceptibility to error. In WATM, traffic control is essential in order to protect the network ...

The success of mobile and ubiquitous computing, coupled with the increasing demand for applications with high Quality of Service (QoS) and Quality of Experience (QoE) requirements, has brought great challenges to the future access networks. Thus, wireless mesh networks distinguish due to its flexibility, redundancy, low-cost and broadband capacity. However, aspects as scalability, availability and reliability, are still challenging. Following the limitations of existing proposals, this paper proposes the Multi-Service ...

During the past few years, multimedia traffic with quality of service (QoS) requirements has become of widespread use. Media servers are usually built as clusters of workstations connected by a high-performance interconnection network. However, these high-performance networks do not usually offer differentiated support for multimedia traffic. The MultiMedia Router (MMR) is a proposal to address the QoS issue in cluster networks within a compact architecture, while also integrating conventional best-effort traffic. This paper describes the main architectural features of the MMR, such as the use of a hybrid switching technique, credit-based flow control, or small input buffers. Also, the main design parameters are tuned by means of simulation. It can be seen how proper differentiation among the different traffic classes is achieved, while retaining a compact design with small buffers.

The multiplexing gain for VBR voice sources depends on the acceptable delay bounds, the voice activity factor, the mean burst length, the mean silence period, the total link capacity. Sensitivity analysis of these factors is presented here. Source:

The performance of dynamic packet reservation multiple access (DPRMA), which was introduced in previous publications, is investigated. In particular, we show here how the DPRMA scheme integrates three different traffic types: voice, video, and data, through a single access control mechanism that permits users to specify their immediate bandwidth requirements. The primary feature of the DPRMA is the dynamic matching

The use of passive optical networks (PONs) enables access rates of multi-Gbit/sec bandwidth and provision of quality of service for high definition multimedia services. In this paper, we consider and analyse a generic multi-priority dynamic bandwidth allocation (DBA) algorithm for TDM PONs serving multimedia traffic in an upstream link. PON traffic is served strictly according to its priority. We consider this DBA algorithm using two approaches: (i) the algorithm assigns a fixed service quantum to each priority service and (ii) different service quanta are assigned to different priority services. The mean message delay is evaluated using a multiqueue processor sharing (MPS) model and an MPS with Heterogeneous Traffic (MPS-HT) model for the two approaches respectively. The MPS model is a classical processor sharing model limited by the critical assumption that there is egalitarian service sharing among all users, which is inefficient for multimedia applications in PONs. We extend the MPS model to a general MPS-HT model that enables the analysis of message delay performance in the case where the service quanta may be different for different services.

The Quality of Service (QoS) requirements such as delay and cell loss ratio (CLR) are very stringent for video transmission. These constraints are difficult to meet if high network utilization is desired. Dynamic bandwidth allocation in which video traffic prediction can play an important role is thus needed. In this paper, we suggest to predict the variation of I frames instead of the actual size of I frames, and propose an algorithm that can achieve fast convergence and small prediction error, thus imposing QoS and attaining high network utilization. The performance of the scheme is studied using the renegotiated constant bit rate (RCBR) service model. The overall dynamic bandwidth allocation scheme based on our fast convergent algorithm is shown to be promising, and practically feasible for efficient transmission of real time videos.

In multimedia wireless sensor network, a routing protocol plays an important role in saving the limited resources of sensors. It allows a node to transmit a multimedia content, an image in our case, to the sink. In this paper, we are going to use the Castralia simulator to test different configurations of leach routing protocol. The aim of these tests is to determine how we can transmit the biggest number of images through network with minimum energy consumption.

Call admission control (CAC) strategies for multimedia traffic in wireless networks is studied. A wireless network cell serving two types of customers; narrowband customers, which require one channel and wideband customers, which require 1 channels is considered. Two CAC strategies; reserve channels strategy (RCS) and threshold strategy (TS) are applied to the wireless cell and their performances are compared. The results show that in most operating conditions, the RCS has a lower blocking probability and probability of handoff call dropping than the TS. Only in the case when the wideband traffic is higher than the narrowband traffic that the weighted probability of handoff call dropping becomes higher for the RCS. Mean server utilization is lower for the threshold CAC than for the reserve channels CAC strategy at most operating conditions. Index Terms-Call admission control (CAC), handoff, qualityof-service (QoS), reserve channels, threshold, wireless networks.

We develop scheduling strategies for carrying multimedia traffic over a polled multiple access wireless network with fading. We consider a slotted system with three classes of traffic (voice, streaming media and file transfers). A Markov model is used for the fading and also for modeling voice packet arrivals and streaming arrivals. The performance objectives are a loss probability for voice, mean network delay for streaming media, and time average throughput for file transfers. A central scheduler (e.g., the access point in a single cell IEEE 802.11 wireless local area network (WLAN)) is assumed to be able to keep track of all the available state information and make the scheduling decision in each slot (e.g., as would be the case for PCF mode operation of the IEEE 802.11 WLAN). The problem is modeled as a constrained Markov decision problem. By using constraint relaxations (a linear relaxation and Whittle type relaxations) an index based policy is obtained. For the file transfers the decision problem turns out to be one with partial state information. Numerical comparisons are provided with the performance obtained from some simple policies.

Recent developments in ATM technology has made multiplexing of a wide range of traffic with diverse performance requirements important. The statistical multiplexing of several traffic types such as voice, video and data can lead to network congestion thus violating the quality of service (QOS) guarantees. In order to meet the performance requirements of the applications an efficient transport protocol and congestion control mechanism becomes necessary. We propose a transport mechanism for guaranteeing application required QOS requirements over an ATM network. Leaky-bucket congestion control scheme is used as the traffic policing mechanism. Source characterization of voice and video are modeled as Markov Modulated Poisson Processes (MMPP) and the proposed transport mechanism is evaluated by simulation on a single and multihop network with multimedia traffic. The performance of the scheme is examined as a function of source characteristics and the effect of statistical multiplexing is also investigated. The results indicate that the leaky-bucket scheme and statistical multiplexing are more effective for bursty traffic. This calls for a dynamic control mechanism to achieve optimal system utilization with guaranteed QOS.

To facilitate higher bandwidth for multimedia traffic, modern mobile routers support simultaneous multi-band communication, leading to less interference, higher capacity and better reliability. However, there exists no quantitative evaluation to judge whether multi-band is better than single band router in realistic scenario. Our main objective in this paper is to find performance of different class of traffic under single and multi-band system with respect to utilization. In this paper, we have used different scheduling algorithms for multi-band routers which transmits different classes of traffic through different frequency bands in order to achieve improved performance. We have provided analytical and simulation results for average queue occupancy, average delay, throughput, and packet drop rate. We show our results comparing multi-band and single band mobile router performances based on different circumstances. It is evident from our results that one of them is not always better than the other. Our work can help ...

The next generation of cellular mobile networks will support multimedia applications. However, these applications differ in terms of QoS (Quality of Service) requirements, each one inflicting constraints which are specific to this kind of environment due to its limited bandwidth. Based on this, in this paper, we propose alternative schemes of CAC (Call Admission Control) combined with adjacent cells bandwidth reservation schemes, in an end-to-end approach. This proposal try to attend various multimedia services according to their QoS requirements, also reducing the dropping probabilities during the handoff procedures, prioritizing the users already admitted in the network. The results based on simulations shows that it is possible to guarantee low levels of CDP (Call Dropping Probabilities), increasing the user satisfaction.

First I want to thank God for giving me the strength to proceed and conclude my research. Secondly, I want to thank my family for supporting me and understanding my moments of solitude and frustration when the investigation did not take the path that was supposed to go. Also, I want to thank my supervisor, Marcelo Segatto, and my co-supervisor, Maria Pontes, for guiding me at the right paths even when I haven't faith or failed to understand where my path was leading, without them I would not be here. I am also thankful to Diogo V. N. Coelho who first guided me in this jurney and was always there to answer my question even the silly ones. I am also grateful for all the assistance of Sabrina Feliz, Rosa Puentes and Breno Frizera, from the human resource team and the technical support from the laboratory that helped me with bureaucratic issues also when they help me to fix my computer, which decided to take a vocation in the middle of my studies. I am also very thankful for all my colleagues and friends that were also in the researching path giving me motivation to not give up because they already had passed through those moments that I was living. At last but not the least, I am really thankful for the National Council for scientific and technological development (CNPq-Conselho Nacional de Desenvolvimento Científico e Tecnológico) organisation also to the Espirito-Santence technology foundation (FEST-Fundação Espírito-Santense de Tecnologia) organization, as those were responsible for providing financial support for this Marter's thesis to be completed. "A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another. By this shall all men know that ye are my disciples, if ye have love one to another".

I n t r o d u c t i o n This chapter offers a state-of-the-art review in mobile ad hoc networks (MANETs). It first introduces the history of ad hoc networks, explaining the ad hoc network concept and referring to the main characteristics of these networks and their fields of application. It then focuses on technologies and protocols specific to ad hoc networks. Firstly, it refers to relevant proposals targeting the PHY/MAC layers. Secondly, it discusses the different routing protocol proposals for ad hoc networks according to the category they belong to. Finally, it includes an overview of the different protocols proposed for ad hoc networks at the transport layer. The chapter concludes with some remarks on future trends in these networks.

Wireless communication is playing an important role in our daily life since it offers flexibility and mobility. Currently, there are more than 3.2 billion users and a hundredfold increase of traffic is expected by the year 2017. In the future, the home and office networking environments are predicted to be dominated by a variety of multimedia services like wireless High-definition and Ultra High-definition television (HD and UHDTV), wireless home entertainment and virtual wireless offices. In order to support these applications, the indoor wireless network should provide the user with a transmission capacity of hundreds of Mbps using short-range Gbps wireless technology and using techniques like antenna diversity, beam-forming, sophisticated coding schemes, etc. With 5 GHz of unlicensed spectrum available at the 60 GHz band, the millimeter wave radio at 60 GHz becomes a promising air interface for future home networks. The wavelength of the 60 GHz band is around 5 mm. This is an adv...

— A Multi-agent System can be defined as a set of agents that interact with each other and with the environment to solve a particular problem in a coordinated (behaviorally coherent) manner. Our paper models Call Admission Control in Cellular networks as Multi Agent resource provisioning problem to provide Service Level Agreement (SLA) in wireless cellular network. For which we modify SHUFFLE model to introduce Network Provider Cell Agent which implements three Call admission strategies namely Static CutOff Priority,

A Multi-agent System can be defined as a set of agents that interact with each other and with the environment to solve a particular problem in a coordinated (behaviorally coherent) manner. Our paper models Call Admission Control in Cellular networks as Multi Agent resource provisioning problem to provide Service Level Agreement (SLA) in wireless cellular network. For which we modify

El artículo explora, a través de una historia de vida, cómo la gestión del desplazamiento dejó de ser una situación temporal y transicional para convertirse en un "oficio" y en un proceso de transformación subjetiva dentro de las dinámicas urbanas de la ciudad de Bogotá. Para ello, se analiza el relato de Teresa, una activista desplazada desde hace una década, que muestra la tensión existente entre el aparato discursivo institucional, la lucha por el reconocimiento y las posibilidades de agencia.

The concept of care-of-address (CoA) is a major cause of excessive handoff delay in Mobile IPv6 for real time multimedia traffic. Many schemes eliminate the use of CoA at the micromobility scale, but leave the macro-mobility unsolved. This paper proposes a novel alternative IPv6 mobility scheme based on universal addressing-Cellular Universal IP (CUIP)-for realtime traffic in wireless access networks. In CUIP, a mobile node is addressed with a universal IP address regardless of its location, making CoA and tunneling unnecessary in micromobility and even macromobility handoffs. CUIP manages roaming and handoff differently-whereas explicit signaling is used for roaming, a handoff-on-the-fly route-update scheme is used during handoff to embed signaling information into the outgoing data packets to minimize handoff delay. We prove analytically that, on average, fewer than three routers need to be updated per handoff. As a result, CUIP incurs an expected network layer handoff delay on the order of milliseconds only. In addition, the support of QoS is possible. A simple security scheme is also proposed to enable mutual authentication at the network layer.

This paper presents a next generation network demonstrator currently under deployment in Aveiro. The demonstrator supports mobile IP with fast handovers with integrated QoS and AAAC issues considerations. A monitoring system provides network information adequate for QoS management, and a specially built QoS Broker is able to manage multiple types of Access Routers. The demonstrator has been tested with some applications, and is currently under refinement.

Current trends in communication networks point to an aggregation of all kind of traffic (data, voice, etc) in the same transport technology. IP is on the lead to be that transport technology and this is valid both for fixed and wireless networks. The usage of IP as a transport technology solves some of the interworking problems between different technologies, but at the same time, the IP Quality of Service (QoS) mechanisms are not fully adapted to the reality of QoS-aware mobility between different technologies. This poses ...

Future telecommunication networks, and in particular networks beyond 3rd Generation, will be based on an “all-IP” architecture. Issues such as Quality of Service (QoS), Mobility and Authentication, Authorisation, Accounting and Charging (AAAC), and their respective interoperation, must be handled in such scenarios. This paper describes a generic end-to-end QoS architecture and its relationship with the other networking components. This architecture is being developed inside the IST project Moby Dick.

The interaction between Authentication, Authorization and Accounting (AAA) systems and the Quality of Service (QoS) infrastructure is to become a must in the near future. This interaction will allow rich control and management of both users and networks. DIAMETER and DiffServ are likely to turn into the future standards in AAA and QoS systems, but they are not designed to interact with each other. To face this, we propose a new Diameter-Diffserv interaction model and describe the Application Specific Module (ASM) implemented to ...

Future telecommunication networks, and in particular networks beyond 3 rd Generation, will be based on an "all-IP" architecture. Issues such as Quality of Service (QoS), Mobility and Authentication, Authorisation, Accounting and Charging (AAAC), and their respective interoperation, must be handled in such scenarios. This paper describes a generic end-to-end QoS architecture and its relationship with the other networking components. This architecture is being developed inside the IST project Moby Dick.

Cellular communication demands for seamless mobility, mobile broadband and multimedia services, LTE is the technology that addresses all these demands. Data rates offered by this technology are up to 1Gbits/sec and offers improved performance at the edge of cell i.e. fast handoff. Due to the high intensity of packets the traffic behavior is bursty; packets/calls arrive in bulks and after getting/without getting service depart in bulks. In censored cell the arrival process is not halted when the system reaches its full capacity i.e. continuous arrival process and the packets/calls that arrive when the system is full are blocked. In this paperLagrange coefficients are determined analytical to carry out Maximum Entropy (ME)analysis of priority censored system for LTE cell, priority is given to handoff calls by assigning dedicated channels. Traffic arrival and departure process follow Generalized exponential distribution i.e. calls arrive for service in burst/s and after getting service...

The aim of the discrete simulation framework is to deal with issues of the next generation of wireless cellular networks (e.g., multimedia traffic, radio resource management and mobility... etc) and to provide a platform for current and future investigations involving wireless cellular networks. The simulator is built from the scratch to enable customization requirements of any research and to provide the freedom to understand, configure protocol modules, draw desired topologies and specifies the movement paths of the mobile users and to plot the necessary performance graphs. In order to evaluate and validate the performance of the designed simulator, a simulation model for the wireless cellular network and mobile environment deployed. The performance of the developed simulator compared with the performance characteristics of existing algorithms. Simulation results verify the developed simulator is able to recapture the results of both the numerical result and simulation results of the comparative system utilizing an idealistic platform. In addition the simulator incorporates detail algorithms for the correlated components between the entities of the cellular networks and the development of the discrete simulator.

Personal communications services (PCS) promise to provide a variety of information exchanges among users with any type of mobility, at any time, in any place, through any available device. To achieve this ambitious goal, two of the major challenges in the system design are: i) to provide a highspeed wireless subsystem with large capacity and acceptable quality-of-service (QoS) and ii) to design a network architecture capable of supporting multimedia traffic and various kinds of user mobility. A time-hopping spread-spectrum wireless communication system called ultra-wide bandwidth (UWB) radio is used to provide communications that are low power, high data rate, fade resistant, and relatively shadow free in a dense multipath environment. Receiver-signal processing of UWB radio is described, and performance of such communications systems, in terms of multiple-access capability, is estimated under ideal multiple-access channel conditions. A UWB-signal propagation experiment is performed using the bandwidth in excess of 1 GHz in a typical modern office building in order to characterize the UWB-signal propagation channel. The experimental results demonstrate the feasibility of the UWB radio and its robustness in a dense multipath environment. In this paper, an ATM network is used as the backbone network due to its high bandwidth, fast switching capability, flexibility, and well-developed infrastructure. To minimize the impact caused by user mobility on the system performance, a hierarchical network-control architecture is postulated. A wireless virtual circuit (WVC) concept is proposed to improve the transmission efficiency and simplify the network control in the wireless subsystem. The key advantage of this network architecture and WVC concept is that the handoff can be done locally most of the time, due to the localized behavior of PCS users.

The recent substantial growing of video and voice traffics in the Internet may cause a great impact on the conception and dimensioning of a network node designed to attend only data traffic. The objective of this paper is to investigate how these traffics can affect the present network which works with FIFO scheduler. For this purpose, a simulation platform consisted of several different kinds of sources, a buffer and a FIFO scheduler was developed in C++ language. Many different scenarios of traffic compositions were simulated for the study of the network node behavior in relation to queue and system times which are important parameters for QoS definition. The results showed that video traffic can impact very strongly all the network infrastructure including the whole congestion of system. The results also showed that voice traffic has less impact on the network but in a mixed operation of traffics, the system cannot guarantee the QoS of voice traffic which needs almost real time treatment. The main conclusion of this paper is that the admission control mechanism and QoS provisioning need to be implemented urgently to cope with the fast growing of video and voice traffics.

More subtle and explicit QoS control mechanisms are required at the radio access level, even though the simple and scalable Differentiated Services (DiffServ) QoS control model is acceptable for the core of the network. At the radio access level, available resources are severely limited and the degree of traffic aggregation is not significant, thus rendering the DiffServ principles less effective. In this paper we present a suitable hybrid QoS architecture framework to address the problem. At the wireless access end, the local QoS mechanism is designed in the context of IEEE 802.11 WLAN with 802.11e QoS extensions; so streams of those session-based applications are admitted, established according to the traffic profile they require, and guaranteed. As the core in the Admission Control of the hybrid QoS architecture, the Fair Intelligent Congestion Control (FICC) algorithm is applied to provide fairness among traffic aggregates and control congestion at the bottleneck interface between the wireless link and the network core via mechanisms of packet scheduling, buffer management, feedback and adjustments. It manages effectively the overloading scenario by preventing traffic violation from uncontrolled traffic, and providing guarantee to the priority traffic in terms of guaranteed bandwidth allocation and specified delay.

In this paper, we propose a traffic control mechanism for ATM switches consisted of common buffered switch fabrics (SF) without buffer separation. The proposed mechanism allocates the rate of incoming traffics into switch fabrics according to the load of output ports. In the method, an egress line interface module (LIM) computes the available bandwidth (ABW) for each connection of non-real time traffics based on the load of the output port. And the egress LIM sends back the ABW to ingress LIMs for each connection. According to the ABW, the ingress LIMs schedule the incoming traffic into SF of each connection. We also propose a rate-based cell-scheduling algorithm for the proposed mechanism. The proposed mechanism has been implemented by using FPGAs in the ACE256 ATM switch.

Quality of Service (QoS) provided by the IEEE 802.11e amendment and by the proposed HCF Controlled Channel Access (HCCA) reference scheduler is tailored for Constant Bit Rate traffic streams. Moreover the numerous alternative scheduling algorithms are not suitable to serve Variable Bit Rate (VBR) traffic streams with the required QoS and real-time guarantees. This paper presents Immediate Dynamic TXOP HCCA (IDTH), a new scheduling algorithm based on a bandwidth reclaiming mechanism suitable to cooperate with a HCCA real-time scheduler. IDTH recovers the portion of the transmission time unused by the scheduled stations to provide a further capacity for the next variable bit rate traffic streams. The transmission opportunity of the next scheduled station is assigned considering the available spare resources and the previously used ones. The scheduling analysis and the simulations results show that IDTH is suitable to reduce the delay experienced by VBR traffic streams, to efficiently deal with the variability of multimedia traffic and to avoid waste of resources.

Nowadays, wireless networks have been deploying everywhere, with IEEE 802.11 as the most popular standard. However, wireless resources are scarce and wireless condition varies often. These limitations are crucial for applications with tight QoS requirements such as video or voice over IP. To cope with the problems, the standard has provided many features including multi-rate capability, which is the focus of this paper. Multi-rate capability is beneficial especially for multicast transmission, in which the traffic sent by default at basic rate may result in capacity wasting because of longer channel occupancy. Moreover the lack of feedback mechanism makes it difficult to deal with reliability or service quality. Some protocols have proposed to use rate adaptation to handle the problems but none of them takes into account quality of experience (QoE), which is an essential quality indicator in multimedia traffic, for making decision. Therefore, we propose in this paper a novel rate-adaptation mechanism based on quality of experience. We make use of PSQA (Pseudo-Subjective Quality Assessment) tool for obtaining mean opinion score in real-time. Our objective is to improve bandwidth utilization while satisfying user experience. We illustrate significant performance improvement obtained by our scheme according to this goal.