565 research outputs found

    MIRAI Architecture for Heterogeneous Network

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    One of the keywords that describe next-generation wireless communications is "seamless." As part of the e-Japan Plan promoted by the Japanese Government, the Multimedia Integrated Network by Radio Access Innovation project has as its goal the development of new technologies to enable seamless integration of various wireless access systems for practical use by 2005. This article describes a heterogeneous network architecture including a common tool, a common platform, and a common access. In particular, software-defined radio technologies are used to develop a multiservice user terminal to access different wireless networks. The common platform for various wireless networks is based on a wireless-supporting IPv6 network. A basic access network, separated from other wireless access networks, is used as a means for wireless system discovery, signaling, and paging. A proof-of-concept experimental demonstration system is available

    Call Admission Control in Mobile Wireless

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    Some problems related to wireless network access are discussed in the article. Special attention is paid to Medium Access Control and Call Admission Control. Both have direct impact on communication link accession. While the first one dictates how to, the second one decides who can access the link. The problems with wireless medium access are mentioned and requirements on MAC protocols are named. Also need for CAC algorithms is illustrated and simple functional example is proposed. Finally, the reasons for future enhancements are shortly discovered

    Flat Cellular (UMTS) Networks

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    Traditionally, cellular systems have been built in a hierarchical manner: many specialized cellular access network elements that collectively form a hierarchical cellular system. When 2G and later 3G systems were designed there was a good reason to make system hierarchical: from a cost-perspective it was better to concentrate traffic and to share the cost of processing equipment over a large set of users while keeping the base stations relatively cheap. However, we believe the economic reasons for designing cellular systems in a hierarchical manner have disappeared: in fact, hierarchical architectures hinder future efficient deployments. In this paper, we argue for completely flat cellular wireless systems, which need just one type of specialized network element to provide radio access network (RAN) functionality, supplemented by standard IP-based network elements to form a cellular network. While the reason for building a cellular system in a hierarchical fashion has disappeared, there are other good reasons to make the system architecture flat: (1) as wireless transmission techniques evolve into hybrid ARQ systems, there is less need for a hierarchical cellular system to support spatial diversity; (2) we foresee that future cellular networks are part of the Internet, while hierarchical systems typically use interfaces between network elements that are specific to cellular standards or proprietary. At best such systems use IP as a transport medium, not as a core component; (3) a flat cellular system can be self scaling while a hierarchical system has inherent scaling issues; (4) moving all access technologies to the edge of the network enables ease of converging access technologies into a common packet core; and (5) using an IP common core makes the cellular network part of the Internet

    Adaptive Quality Of Service Call Admission Control With User Mobility Prediction For Multimedia Traffic Over Wireless Networks

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    Multimedia traffic is expected to be supported in the next generation 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. Some challenging problems that appear in multimedia wireless networks, such as user mobility and shortage of bandwidth, influence the QoS provisioning for the users. In this thesis, we propose a new framework called Adaptive quality of service (AdQoS) to guarantee the QoS of multimedia traffic. The objectives that AdQoS framework tries to accomplish are minimum new call blocking and handoff dropping rates. The key feature of this framework is the bandwidth reallocation scheme. This scheme is developed to control the bandwidth operation of ongoing connections when the system is overloaded. The other key feature is the bandwidth reservation scheme incorporating a user mobility prediction to manage the QoS of the networks. Based on the mobility prediction, bandwidth is reserved to guarantee the uninterrupted hand off process. A comparison between existing user mobility prediction and the proposed scheme is also presented. An integrated system, which combines the Bandwidth Allocation Level technique and the user mobility prediction, is also proposed. The proposed user mobility prediction algorithm integrates the Received Signal Strength (RSS) measurements for the mobile terminal's intra-cell movement and aggregate history of mobile terminals for inter-cell movement. When compared with the conventional scheme proposed in the literature, the simulation results show that our proposed scheme reduces the new call blocking probabilities, the handoff dropping probabilities and reduces significantly the probability of terminating calls while still maintaining efficient bandwidth usage

    Buffer management and cell switching management in wireless packet communications

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    The buffer management and the cell switching (e.g., packet handoff) management using buffer management scheme are studied in Wireless Packet Communications. First, a throughput improvement method for multi-class services is proposed in Wireless Packet System. Efficient traffic management schemes should be developed to provide seamless access to the wireless network. Specially, it is proposed to regulate the buffer by the Selective- Delay Push-In (SDPI) scheme, which is applicable to scheduling delay-tolerant non-real time traffic and delay-sensitive real time traffic. Simulation results show that the performance observed by real time traffics are improved as compared to existing buffer priority scheme in term of packet loss probability. Second, the performance of the proposed SDPI scheme is analyzed in a single CBR server. The arrival process is derived from the superposition of two types of traffics, each in turn results from the superposition of homogeneous ON-OFF sources that can be approximated by means of a two-state Markov Modulated Poisson Process (MMPP). The buffer mechanism enables the ATM layer to adapt the quality of the cell transfer to the QoS requirements and to improve the utilization of network resources. This is achieved by selective-delaying and pushing-in cells according to the class they belong to. Analytical expressions for various performance parameters and numerical results are obtained. Simulation results in term of cell loss probability conform with our numerical analysis. Finally, a novel cell-switching scheme based on TDMA protocol is proposed to support QoS guarantee for the downlink. The new packets and handoff packets for each type of traffic are defined and a new cutoff prioritization scheme is devised at the buffer of the base station. A procedure to find the optimal thresholds satisfying the QoS requirements is presented. Using the ON-OFF approximation for aggregate traffic, the packet loss probability and the average packet delay are computed. The performance of the proposed scheme is evaluated by simulation and numerical analysis in terms of packet loss probability and average packet delay

    Wireless Internet on Heterogeneous Networks

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    An Analytical Approach for Mobility Load Balancing in Wireless Networks

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    Management of mobility especially balancing the load of handoff for wireless networks is an essential parameter for wireless network design and traffic study. In this paper, we present analytical mobility management in high speed wireless mobile networks focusing on factors such as the number of channel slots and offered load. We demonstrate the performance of handoffs with mobility consideration using several metrics including the alteration of states prior to reaching a cell boundary, the speed of mobile terminal, and the distance between a mobile terminal and a cell boundary. We mainly focus on the performance evaluation for the factor of mobility with taking into account the high speed status of a user
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