Design and Analysis of a Channel Assignment Scheme for CDMA/TDMA Mobile Networks

In this paper, a channel assignment scheme is proposed for use in CDMA/TDMA mobile networks carrying voice and data traffic. In each cell, three types of calls are assumed to compete for access to the limited number of available channels by the cell: new voice calls, handoff voice calls, and data calls. The scheme uses the movable boundary concept in both the code and time domains in order to guarantee the quality of service (QoS) requirements of each type. A traditional Markov analysis method is employed to evaluate the performance of the proposed scheme. Measures, namely, the new call blocking probability, the handoff call forced termination probability, the data call loss probability, the expected number of handoff and the handoff link maintenance probability are obtained from the analysis. The numerical results, which are validated by simulation, indicate that the scheme helps meet the QoS requirements of the different call types.     

Aggregate History of User Mobility Pattern for QoS Provisioning in Multimedia Wireless Networks

Multimedia traffic is expected to be included in the next generation of wireless networks. As in wireline networks, the wireless network must also be capable of providing guaranteed quality-of-service (QoS) over the lifetime of mobile connections. In this paper, a bandwidth reservation scheme incorporating a user mobility prediction is proposed to manage the QoS of the networks. The mobility prediction scheme is developed based on the aggregate history of mobile users. Based on the mobility prediction, bandwidth is reserved to guarantee the uninterrupted handoff process. Simulation results demonstrate that the proposed scheme can guarantee the required QoS requirements in terms of handoff call dropping probability and new call blocking probability while maintaining efficient bandwidth utilization.     

A Variable Slot Length TDMA Protocol for Personal Communication Systems

We present a new TDMA-based scheme intended for carrying traffic withdiverse QoS requirements in mobile environments, e.g.,Personal Communication Systems (PCS).In contrast to mostother TDMA protocols for mobile applications, instead oftrying to fit the offered traffic to the slot size, our solution adaptsthe slot size to the offered traffic.This feature is combined with a dynamic and responsive bandwidth scheduler.As demonstrated by our performance studies, the proposedscheme is more flexible and incurs lower bandwidth overhead than otherTDMA-based solutions.     

A comprehensive resource management framework for next generation wireless networks

We propose an integrated resource management approach that can be implemented in next generation wireless networks that support multimedia services (data, voice, video, etc.). Specifically, we combine the use of position-assisted and mobility predictive advanced bandwidth reservation with a call admission control and bandwidth reconfiguration strategy to support flexible QoS management. We also introduce a mobile agent based framework that can be used to carry out the functions of geolocation and of the proposed resource management in wireless networks. A model is also developed to obtain the optimal location information update interval in order to minimize the total cost of the system operation. The comparison of the achievable performance results of our proposed scheme with the corresponding results of a conventional system that supports advanced bandwidth reservation only, as means of supporting the QoS requirements, demonstrate that our integrated scheme can alleviate the problem of overreservation, support seamless operation throughout the wireless network, and increase significantly the system capacity.     

Mobile flow-aware networks for mobility and QoS support in the IP-based wireless networks

As the volume of mobile traffic consisting of video, voice, and data is rapidly expanding, a challenge remains with the mobile transport network, which must deliver data traffic to mobile devices without degrading the service quality. Since every Internet service holds its own service quality requirements, the flow-aware traffic management in fine granularity has been widely investigated to guarantee Quality of Service (QoS) in the IP networks. However, the mobile flow-aware management has not been sufficiently developed yet because of the inherent constraints of flow routing in the mobile networks regarding flow-aware mobility and QoS support. In this paper, we propose a flow-aware mobility and QoS support scheme called mobile flow-aware network (MFAN) for IP-based wireless mobile networks. The proposed scheme consists of dynamic handoff mechanisms based on QoS requirements per flow to reduce the processing overhead of the flow router while ensuring QoS guarantee to mobile flows. The performance analyses of the proposed scheme demonstrate that MFAN successfully supports the mobile flow traffic delivery while satisfying the QoS requirement of flows in the wireless mobile IP networks.     

A new protocol for the integration of voice and data over PRMA

In packet reservation multiple access (PRMA) the receiver in the mobile terminal is required to listen continuously to monitor the acknowledgment messages broadcasted at the end of every time slot. A new scheme for the integration of voice and data based on PRMA is proposed. The voice and the data subsystems are logically separated. The total available bandwidth is divided into three regions-voice information, voice contention, and data regions. The available bandwidth is dynamically partitioned between the above three regions subject to the fulfillment of the quality of service (QoS) requirements of the voice users. The voice subsystem has been modeled as a Markov chain and an exact analytical method used to compute the voice packet dropping probability is described. A nonlinear programming problem is formulated to optimize the bandwidth allocated for the data users. Solutions to this nonlinear programming problem that are very close to optimum have been obtained heuristically. Numerical results indicate that a significant amount of data traffic can be supported without sacrificing the voice capacity of the system     

Dynamic-Grouping bandwidth reservation scheme for multimedia wireless networks

In wireless networks carrying multimedia traffic (voice, video, data, and image), it becomes necessary to provide a quality-of-service(QoS) guarantee for multimedia traffic connections supported by the network. In order to provide mobile hosts with high QoS in the next-generation wireless networks, efficient and better bandwidth reservation schemes must be designed. This paper presents a novel dynamic-grouping bandwidth reservation scheme as a solution to support QoS guarantees in the next-generation wireless networks. The proposed scheme is based on the probabilistic resource estimation to provide QoS guarantees for multimedia traffic in wireless cellular networks. We establish several reservation time sections, called groups, according to the mobility information of mobile hosts of each base station. The amount of reserved bandwidth for each base station is dynamically adjusted for each reservation group. We use the dynamic-grouping bandwidth reservation scheme to reduce the connection blocking rate and connection dropping rate, while increasing the bandwidth utilization. The simulation results show that the dynamic-grouping bandwidth reservation scheme provides less connection-blocking rate and less connection-dropping rate and achieves high bandwidth utilization.     

Design and performance evaluation of an RRA scheme for voice‐data channel access in outdoor microcellular environments

In PCS networks, the multiple access problem is characterized by spatially dispersed mobile source terminals sharing a radio channel connected to a fixed base station. In this paper, we design and evaluate a reservation random access (RRA) scheme that multiplexes voice traffic at the talkspurt level to efficiently integrate voice and data traffic in outdoor microcellular environments. The scheme involves partitioning the time frame into two request intervals (voice and data) and an information interval. Thus, any potential performance degradation caused by voice and data terminals competing for channel access is eliminated. We consider three random access algorithms for the transmission of voice request packets and one for the transmission of data request packets. We formulate an approximate Markov model and present analytical results for the steady state voice packet dropping probability, mean voice access delay and voice throughput. Simulations are used to investigate the steady state voice packet dropping distribution per talkspurt, and to illustrate preliminary voice-data integration considerations. This revised version was published online in June 2006 with corrections to the Cover Date.     

An uplink CDMA system architecture with diverse QoS guarantees forheterogeneous traffic

The uplink access control problems for cellular code-division multiple-access (CDMA) systems that service heterogeneous traffic with various types of quality-of-service (QoS) and use multicode CDMA to support variable bit rates are addressed. Considering its distinct QoS requirements, class-I real-time traffic (e.g., voice and video) is differentiated from class-II non-real-time traffic (e.g., data). Connection-oriented transmission is achieved by assigning mobile-oriented code channels for class-I traffic, where each corresponding mobile needs to pass an admission test. Class-II traffic is transmitted in a best-effort manner through a transmission-rate request access scheme which utilizes the bandwidth left unused by class-I traffic. Whenever a mobile has class-II messages to transmit, the mobile requests code channels via a base station-oriented transmission-request code channel, then, according to the base station scheduling, the transmission is scheduled and permitted. Addressed are the admission test for class-I connections, transmission power allocation, and how to maximize the aggregate throughput for class-II traffic. The admission region of voice and video connections and the optimum target signal-to-interference ratio of class-II traffic are derived numerically. The performance of class-II traffic transmissions in terms of average delay is also evaluated and discussed     

Optimal resource allocation and adaptive call admission control for voice/data integrated cellular networks

Resource allocation and call admission control (CAC) are key management functions in future cellular networks, in order to provide multimedia applications to mobiles users with quality of service (QoS) guarantees and efficient resource utilization. In this paper, we propose and analyze a priority based resource sharing scheme for voice/data integrated cellular networks. The unique features of the proposed scheme are that 1) the maximum resource utilization can be achieved, since all the leftover capacity after serving the high priority voice traffic can be utilized by the data traffic; 2) a Markovian model for the proposed scheme is established, which takes account of the complex interaction of voice and data traffic sharing the total resources; 3) optimal CAC parameters for both voice and data calls are determined, from the perspective of minimizing resource requirement and maximizing new call admission rate, respectively; 4) load adaption and bandwidth allocation adjustment policies are proposed for adaptive CAC to cope with traffic load variations in a wireless mobile environment. Numerical results demonstrate that the proposed CAC scheme is able to simultaneously provide satisfactory QoS to both voice and data users and maintain a relatively high resource utilization in a dynamic traffic load environment. The recent measurement-based modeling shows that the Internet data file size follows a lognormal distribution, instead of the exponential distribution used in our analysis. We use computer simulations to demonstrate that the impact of the lognormal distribution can be compensated for by conservatively applying the Markovian analysis results.     

基于排队理论的信道分配算法研究

针对蜂窝移动通信系统,基于排队理论提出了一种信道分配方案。该方案将信道分为2部分:语音信道和数据保护信道。预留数据保护信道用于补偿数据丢包率,同时对语音业务设置FIFO排队缓冲器,切换呼叫优先占用缓冲器以确保切换优先。当语音信道空闲时,数据业务可以占用语音信道,一旦有语音呼叫请求到来且无可用语音信道,数据业务应释放占用的语音信道,在数据缓存器中排队等待。仿真结果表明该方案不仅降低了新增呼叫阻塞率和切换掉话率,而且提升了数据业务的性能。     

A slotted multicode CDMA protocol for efficient integration of voice and data in cellular networks

This paper presents a novel radio channel structure based on slotted CDMA technology intended for carrying traffic with diverse bandwidth/QoS requirements in mobile environments, e.g. personal communication systems (PCS). The essence of our approach is a combination of flexible slotting with allocation of multiple codes to high‐bandwidth mobiles. As demonstrated by our performance studies, the proposed scheme efficiently integrates multiple traffic classes into a unified CDMA system. It is highly flexible and incurs low overheads for a wide range of realistic traffic conditions. Copyright © 2002 John Wiley & Sons, Ltd.     

End-to-End Adaptive QoS Provisioning over GPRS Wireless Mobile Network

The General Packet Radio Service (GPRS) offers performance guaranteed packet data services to mobile users over wireless frequency-division duplex links with time division multiple access, and core packet data networks. This paper presents a dynamic adaptive guaranteed Quality-of-Service (QoS) provisioning scheme over GPRS wireless mobile links by proposing a guaranteed QoS media access control (GQ-MAC) protocol and an accompanying adaptive prioritized-handoff call admission control (AP-CAC) protocol to maintain GPRS QoS guarantees under the effect of mobile handoffs. The GQ-MAC protocol supports bounded channel access delay for delay-sensitive traffic, bounded packet loss probability for loss-sensitive traffic, and dynamic adaptive resource allocation for bursty traffic with peak bandwidth allocation adapted to the current queue length. The AP-CAC protocol provides dynamic adaptive prioritized admission by differentiating handoff requests with higher admission priorities over new calls via a dynamic multiple guard channels scheme, which dynamically adapts the capacity reserved for dealing with handoff requests based on the current traffic conditions in the neighboring radio cells. Integrated services (IntServ) QoS provisioning over the IP/ATM-based GPRS core network is realized over a multi-protocol label switching (MPLS) architecture, and mobility is supported over the core network via a novel mobile label-switching tree (MLST) architecture. End-to-end QoS provisioning over the GPRS wireless mobile network is realized by mapping between the IntServ and GPRS QoS requirements, and by extending the AP-CAC protocol from the wireless medium to the core network to provide a unified end-to-end admission control with dynamic adaptive admission priorities.     

Call admission control for voice/data integration, in.broadband, wireless networks

This paper addresses bandwidth allocation for an integrated voice/data broadband mobile wireless network. Specifically, we propose a new admission control scheme called EFGC, which is an extension of the well-known fractional guard channel scheme proposed for cellular networks supporting voice traffic. The main idea is to use two acceptance ratios, one for voice calls and the other for data calls in order to maintain the proportional service quality for voice and data traffic while guaranteeing a target handoff failure probability for voice calls. We describe two variations of the proposed scheme: EFGC-REST, a conservative approach which aims at preserving the proportional service quality by sacrificing the bandwidth utilization, and EFGC-UTIL, a greedy approach which achieves higher bandwidth utilization at the expense of increasing the handoff failure probability for voice calls. Extensive simulation results show that our schemes satisfy the hard constraints on handoff failure probability and service differentiation while maintaining a high bandwidth utilization.     

Q-Win – A New Admission and Handoff Management Scheme for Multimedia LEO Satellite Networks

Low Earth Orbit (LEO) satellite networks are deployed as an enhancement to terrestrial wireless networks in order to provide broadband services to users regardless of their location. In addition to global coverage, these satellite systems support communications with hand-held devices and offer low cost-per-minute access cost, making them promising platform for Personal Communication Services (PCS). LEO satellites are expected to support multimedia traffic and to provide their users with the negotiated Quality of Service (QoS). However, the limited bandwidth of the satellite channel, satellite rotation around the Earth and mobility of end-users makes QoS provisioning and mobility management a challenging task. One important mobility problem is the intra-satellite handoff management. The main contribution of this work is to propose Q-Win, a novel call admission and handoff management scheme for LEO satellite networks. A key ingredient in our scheme is a companion predictive bandwidth allocation strategy that exploits the topology of the network and contributes to maintaining high bandwidth utilization. Our bandwidth allocation scheme is specifically tailored to meet the QoS needs of multimedia connections. The performance of Q-Win is compared to that of two recent schemes proposed in the literature. Simulation results show that our scheme offers low call dropping probability, providing for reliable handoff of on-going calls, good call blocking probability for new call requests, while maintaining bandwidth utilization high.     

A Novel Optimal Channel Partitioning Algorithm for Integrated Wireless and Mobile Networks

How to efficiently support multi-class services is a very important issue in integrated wireless and mobile networks because each type of services has distinct characteristics and quality of service (QoS) requirements. This paper presents an efficient algorithm for near optimal channel allocation when different types of services are to be provided in the next generation integrated wireless and mobile networks. We specifically propose a preemptive priority scheme for an integrated wireless and mobile network by first dividing channels into three independent groups and classifying traffic into four different types. The proposed system is modeled by a multi-dimension Markov chain model. Then such a model is used to obtain a set of relations that correlate performances with various system parameters. A novel recursive algorithm is developed to determine the minimal number of channels in each channel group that would be necessary to satisfy the QoS requirements. We also investigate the impact of load ratio for different types of traffic on channel assignment. Finally, we discuss some limitations of our approach and indicate possible future work. We believe that the partitioning scheme proposed in this paper can become a starting point for analysis of future integrated wireless and mobile networks.     

QoS-aware routing based on bandwidth estimation for mobile ad hoc networks

Routing protocols for mobile ad hoc networks (MANETs) have been explored extensively in recent years. Much of this work is targeted at finding a feasible route from a source to a destination without considering current network traffic or application requirements. Therefore, the network may easily become overloaded with too much traffic and the application has no way to improve its performance under a given network traffic condition. While this may be acceptable for data transfer, many real-time applications require quality-of-service (QoS) support from the network. We believe that such QoS support can be achieved by either finding a route to satisfy the application requirements or offering network feedback to the application when the requirements cannot be met. We propose a QoS-aware routing protocol that incorporates an admission control scheme and a feedback scheme to meet the QoS requirements of real-time applications. The novel part of this QoS-aware routing protocol is the use of the approximate bandwidth estimation to react to network traffic. Our approach implements these schemes by using two bandwidth estimation methods to find the residual bandwidth available at each node to support new streams. We simulate our QoS-aware routing protocol for nodes running the IEEE 802.11 medium access control. Results of our experiments show that the packet delivery ratio increases greatly, and packet delay and energy dissipation decrease significantly, while the overall end-to-end throughput is not impacted, compared with routing protocols that do not provide QoS support.     

Performance evaluation of the RQMA-CDMA scheme for multimedia traffic with QoS guarantees

The rapid growth of cellular mobile technology in recent years, coupled with the explosive growth of the Internet, has significantly increased the demand for wireless data services. Traffic on mobile devices is expected to be a mix of real-time traffic such as video, voice, and data, with users requiring diverse quality of service (QoS) guarantees for different types of traffic (video, voice and data). One of the primary challenges of providing QoS is how to prioritize and allocate network resources among contending applications. In order to achieve these goals, a scheduling scheme that can provide equitable and effective packet routing is required. This paper proposes a scheduling scheme called remote queuing multiple access-code division multiple access (RQMA-CDMA), whose purpose is to equitably assign bandwidth resources with QoS guarantees to different mobile devices. RQMA-CDMA is a rate scheduling scheme that can be used to assign bandwidth resources in conjunction with GPS (generalized processor sharing). Additionally, we analyze an admission control that is based on signal to interference plus noise ratio (SINR) for multimedia traffic. Finally, the performance of RQMA-CDMA is evaluated and compared to schemes based on CDMA-GPS according to dropped packets, delay, and throughput.     

Performance evaluation of priority based adaptive multiguard channel call admission control for multiclass services in mobile networks

The CAC (call admission control), which can guarantee call services to meet their QoS (Quality of Service) requirements, plays a significant role in providing QoS in wireless mobile networks. In this paper, an adaptive multiguard channel scheme‐based CAC strategy is proposed to prioritize traffic types and handoff calls. The major aim of the study is to develop the analytical model of the priority traffic and handoff calls based adaptive multiguard channel scheme and examining the performance through setting the value of the adaptive ratio parameters. Our proposed scheme tries to mediate the advantages and drawbacks of the static and dynamic CAC schemes. The proposed scheme is quite different from previous studies because multithreshold values have been considered for multiclass traffic by adaption parameters, and a closed form analytical model is developed The numerical results show that this scheme can be used to keep the targeted QoS requirement by suitably setting the adaptive ratio parameters. Copyright © 2011 John Wiley & Sons, Ltd.     

Quality-of-service provisioning system for multimedia transmission in IEEE 802.11 wireless LANs

IEEE 802.11, the standard of wireless local area networks (WLANs), allows the coexistence of asynchronous and time-bounded traffic using the distributed coordination function (DCF) and point coordination function (PCF) modes of operations, respectively. In spite of its increasing popularity in real-world applications, the protocol suffers from the lack of any priority and access control policy to cope with various types of multimedia traffic, as well as user mobility. To expand support for applications with quality-of-service (QoS) requirements, the 802.11E task group was formed to enhance the original IEEE 802.11 medium access control (MAC) protocol. However, the problem of choosing the right set of MAC parameters and QoS mechanism to provide predictable QoS in IEEE 802.11 networks remains unsolved. In this paper, we propose a polling with nonpreemptive priority-based access control scheme for the IEEE 802.11 protocol. Under such a scheme, modifying the DCF access method in the contention period supports multiple levels of priorities such that user handoff calls can be supported in wireless LANs. The proposed transmit-permission policy and adaptive bandwidth allocation scheme derive sufficient conditions such that all the time-bounded traffic sources satisfy their time constraints to provide various QoS guarantees in the contention free period, while maintaining efficient bandwidth utilization at the same time. In addition, our proposed scheme is provably optimal for voice traffic in that it gives minimum average waiting time for voice packets. In addition to theoretical analysis, simulations are conducted to evaluate the performance of the proposed scheme. As it turns out, our design indeed provides a good performance in the IEEE 802.11 WLAN's environment, and can be easily incorporated into the hybrid coordination function (HCF) access scheme in the IEEE 802.11e standard.