Dynamic reservation TDMA protocol for wireless ATM networks

A dynamic reservation time division multiple access (DR-TDMA) control protocol that extends the capabilities of asynchronous transfer mode (ATM) networks over the wireless channel is proposed in this paper. DR-TDMA combines the advantages of distributed access and centralized control for transporting constant bit rate (CBR), variable bit rate (VBR), and available bit rate (ABR) traffic efficiently over a wireless channel. The contention slots access for reservation requests is governed by the framed pseudo-Bayesian priority (FPBP) Aloha protocol that provides different access priorities to the control packets in order to improve the quality-of-service (QoS) offered to time sensitive connections. DR-TDMA also features a novel integrated resource allocation algorithm that efficiently schedules terminals' reserved access to the wireless ATM channel by considering their requested bandwidth and QoS. Integration of CBR, voice, VBR, data, and control traffic over the wireless ATM channel using the proposed DR-TDMA protocol is considered in this paper. Simulation results are presented to show that the protocol respects the required QoS of each traffic category while providing a highly efficient utilization of approximately 96% for the wireless ATM channel     

A hybrid handover protocol for local area wireless ATM networks

While handovers of voice calls in a wide area mobile environment are well understood, handovers of multi-media traffic in a local area mobile environment is still in its early stage of investigation. Unlike the public wireless networks, handovers for multi-media Wireless LANs (WLANs) have special requirements. In this paper, the problems and challenges faced in a multi-media WLAN environment are outlined and a multi-tier wireless cell clustering architecture is introduced. Design issues for multi-media handovers are specified and a fast, continuous and efficient hybrid handover protocol is proposed. The protocol is scalable and supports source and destination mobile handovers in a mutually exclusive manner. Crossover switch (CX) discovery is also introduced to support fast inter-cluster handovers with consideration given to Mobile Quality of Service (M-QoS). The resulting wireless ATM LAN exhibits a distributed mobile location management, call admission control and handover management architecture. A prototype of the proposed handover protocol is implemented into a Cambridge Fairisle ATM switch and the results of handovers for a single Mobile Host (MH) with a single on-going connection are evaluated. It was found that implementing transport mobility for a wireless ATM environment is not practical as the cell re-routing function changes the traffic characteristics and is not scalable to increasing cell rate and to the number of mobile connections. The data-link layer mobility implementation however, is found to work well. The protocol provides symmetric data disruption to traffic flows in both directions and up to seventy-five intra-cluster handovers can be supported in a second. Throughout the experiment, cells arrive in sequence with no cell loss observed during the handover, up to the capacity limit of the ATM switch. Finally, zig-zag handovers and handovers for a single MH with multiple on-going unicast connections are performed in order to evaluate the robustness and performance of the protocol under different MHs' migration and communication environment.Parts of this paper appeared in the ACM First International Conference on Mobile Computing and Networking (MOBICOM'95), Berkeley, California, November 1995 as The Design & Implementation of A Hybrid Handover Protocol For Multi-Media Wireless LANs.C-K Toh is supported by a King's College Cambridge External Research Studentship and a Cambridge Commonwealth Trust Scholarship.     

A distributed control strategy for wireless ATM networks

Cellular networks are expected to be upgraded to offer Personal Communication Services (PCS). The mobility management and wireless call control approach used in cellular networks are currently being proposed for use in PCS networks. Recent work indicates that both the signaling load and database update rates caused by these mobility management and call control procedures will increase significantly in next generation PCS networks. In this paper, we propose and analyze a new cluster-based architecture and define algorithms to effectively handle mobility management and call control functions for PCS. We assume an ATM network infrastructure. Some of the key aspects of our proposal include simplifying the mobile location and tracking function, performing connection setup in segments, eliminating the need for user service profile downloads between networks, and more efficient routing of connections by removing the need for an anchor switch. Advantages of this approach include a reduction in signaling traffic load, improved call/connection setup delays, and more efficient routing of connections. We carry out an analysis of our solution for high-tier PCS applications.     

Performance of a hybrid multilevel error control with an early-stop ARQ protocol for wireless ATM networks

This paper proposes an effective hybrid multilevel error control (HMEC) with an early-stop automatic repeat request (ARQ) scheme for wireless asynchronous transfer mode (ATM) networks. In this scheme, the source traffic is segmented into a number of blocks, each with m cells, then encoded into k(k>m) cells. The transmission of one block may be finished as long as m out of the k cells are received correctly. The ARQ protocol is applied only when too many cells are dropped or corrupted due to uncorrectable error in the radio channel. This paper also provides a detail study of the proposed scheme. In particular, the throughput efficiency with parameters (m,k) are derived analytically for the white Gaussian and Rayleigh fading channels. Simulation results show a very close match with theoretical results. All the results show that the HMEC scheme can reduce cell-retransmission probability and improve network throughput over a wide range of channel error rates when appropriate values of parameters m and k are chosen.     

A control and management network for wireless ATM systems

This paper describes the design of a control and management network (orderwire) for a mobile wireless Asynchronous Transfer Mode (ATM) network. This mobile wireless ATM network is part of the Rapidly Deployable Radio Network (RDRN). The orderwire system consists of a packet radio network which overlays the mobile wireless ATM network. Each network element in this network uses Global Positioning System (GPS) information to control a beamforming antenna subsystem which provides for spatial reuse. This paper also proposes a novel Virtual Network Configuration (VNC) algorithm for predictive network configuration. A mobile ATM Private Network–Network Interface (PNNI) based on VNC is also discussed. Finally, as a prelude to the system implementation, results of a Maisie simulation of the orderwire system are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Mobility support for IP over wireless ATM

A wireless ATM system consists of a core network infrastructure that provides mobility support to end terminals and a wireless access link. This article outlines two schemes for supporting mobility of IP terminals in this network. In the first scheme, location management and handoff support is integrated within the ATM signaling and control framework (“mobile ATM”), and mobility is transparently supported at the IP layer by mobile ATM underneath. In the second approach, the IP protocol stack is directly executed on ATM switches (without an intermediate ATM signaling stack) using an IP switching technique called IPSOFACTO (IP Switching Over Fast ATM Cell Transport), and terminal mobility is supported via mobile IP     

Hierarchical distributed management clustering protocol for wireless sensor networks

In recent years, there has been a marked increase in the use of wireless sensor networks in various environments such as crisis areas, military operations, and monitoring systems. These networks do not use a fixed network infrastructure and therefore they are a popular choice for highly dynamic environments. One of the main concerns in these networks is the topology management issue, which the clustering method is a subfield for that. The main objective of clustering methods is optimizing the energy consumption. This paper proposes a new clustering protocol, which uses many parameters such as the activity history of each node, local and general state of nodes and their resources condition to determine the best cluster heads and members of each cluster that can increase the network lifetime, fair resource consumption and network coverage.     

Mobility control for achieving optimal configuration in wireless sensor networks

Recent work in wireless sensor networks, or simply called WSNs, has drawn attention to the mobility capability of each node. In Stojmenovic and Lin (IEEE Trans Parallel Distrib Syst 12: 1023–1032, 2001), it is proved that the optimal positions of the relay nodes along a single active flow must lie entirely on the line between the source and destination with each node spaced evenly along such a line. Based on this, we propose two practical solutions to control the relay nodes in WSNs to approach their optimal positions in the local relative coordinate system. One uses one-hop neighbor information and the other one uses two-hop neighbor information. Basically, each relay node will approach the midpoint on the line composed of neighbors. For the latter control scheme, we also discuss its different implementation with outdated two-hop neighbor information (lagged by one-round neighbor information exchange and update). This is an improvement since given nodes only reuse the two-hop neighbor information previously saved at its one-hop neighbors and does not require any extra neighbor information collection. All the new methods prevent oscillations by demanding minimal moving distance per round (MDPR), otherwise the node does not move. Unlike the one presented in Goldenberg et al. (Proceedings of the 5th ACM International Symposium on Mobile Ad Hoc Networking and Computing (Mobihoc’04), pp 163–174 2004) using only one-hop neighbor information, our methods will converge more quickly. The experimental results show a substantial improvement on the speed of achieving the optimal configuration and the total moving distance of nodes.     

An efficient demand-assignment multiple access protocol for wireless packet (ATM) networks

In a wireless packet (ATM) network that supports an integrated mix of multimedia traffic, the channel access protocol needs to be designed such that mobiles share the limited communications bandwidth in an efficient manner: maximizing the utilization of the frequency spectrum and minimizing the delay experienced by mobiles. In this paper, we propose and study an efficient demand-assignment channel access protocol, which we call Distributed-Queueing Request Update Multiple Access (DQRUMA). The protocol can be used for a wide range of applications and geographic distances. Mobiles need to send requests to the base station only for packets that arrive to an empty buffer. For packets that arrive to a non-empty buffer, transmission requests are placed collision-free by piggybacking the requests with packet transmissions. The simulation results show that even with the worst possible traffic characteristics, the delay-throughput performance of DQRUMA is close to the best possible with any access protocol. In addition, explicit slot-by-slot announcement of the transmit permissions gives the base station complete control over the order in which mobiles transmit their packets. This important feature helps the base station satisfy diverse Quality-of-Service (QoS) requirements in a wireless ATM network.     

An integrated multicast connection management solution for wiredand wireless ATM networks

With the prospect of commercializing wireless ATM networks fast becoming a reality, and ATM becoming one of the main network technologies for multimedia computing, the design of ATM connection management solutions has to take into consideration these recent developments. Unfortunately, current ATM signaling solutions standardized by the ATM Forum have to be modified extensively in order to support wireless ATM. Furthermore, these solutions have not delivered a suitable multicast service which can support the communication requirements found in today's computer-based multimedia applications. The work described here therefore addresses these shortcomings by proposing a new multicast connection service architecture and its related algorithms. Some of the important concepts elaborated in the design include the notion of open signaling, the use of logical multicast groups to handle all connections, and seamless support for host mobility     

Mobility in wireless networks

Ohne Zusammenfassung     

Stochastic control of path optimization for inter-switch handoffsin wireless ATM networks

One of the major design issues in wireless ATM networks is the support of inter-switch handoffs. An inter-switch handoff occurs when a mobile terminal moves to a new base station connecting to a different switch. Apart from resource allocation at the new base station, inter-switch handoff also requires connection rerouting. With the aim of minimizing the handoff delay while using the network resources efficiently, the two-phase handoff protocol uses path extension for each inter-switch handoff, followed by path optimization if necessary. The objective of this paper is to determine when and how often path optimization should be performed. The problem is formulated as a semi-Markov decision process. Link cost and signaling cost functions are introduced to capture the tradeoff between the network resources utilized by a connection and the signaling and processing load incurred on the network. The time between inter-switch handoffs follows a general distribution. A stationary optimal policy is obtained when the call termination time is exponentially distributed. Numerical results show significant improvement over four other heuristics     

A signaling and control architecture for mobility support in wireless ATM networks

This paper presents a signaling and control architecture for mobility support in a wireless ATM network that provides integrated broadband services to mobile terminals. A system level protocol architecture for a wireless ATM network is outlined. The proposed protocol stack incorporates new wireless link MAC, DLC and wireless control sublayers, together with appropriate mobility extensions to the existing ATM network control layer. Wireless control and ATM signaling capabilities required for mobility support are discussed, and preliminary solutions are given for selected major functions. Potential extensions to standard Q.2931 ATM signaling are proposed to support handoff and service parameter/QoS renegotiation required for mobility. An associated wireless control protocol for supporting terminal migration, resource allocation, and handoff is discussed. Preliminary experimental results are given which validate the proposed handoff control protocol on an ATM network testbed.     

Mobility-aware timeout medium access control protocol for wireless sensor networks

Wireless sensor networks (WSNs), has been under development for a while by the academia and industry. Due to limited computational power, a typical sensor node may experience operational challenges. Moreover, mobility has become an important feature since emergency and healthcare related applications are evolving in WSNs. Consideration of mobile nodes in WSNs introduce new challenges for the designers. In this paper, an enhanced version of T-MAC protocol (a well-known medium access control protocol in WSNs) known as MT-MAC is proposed. Using the capturing fluctuation in RSSI and LQI values of the received SYNC packets, MT-MAC solves high packet drop ratio in T-MAC. By detecting the mobility, a mobile node softly handover to a new virtual cluster without losing connection with other nodes. The performance of the proposed solution is then compared with T-MAC, S-MAC as well as other well-known mobility-aware MAC (MS-MAC) protocol. The simulation results show that the proposed protocol significantly increases the throughput and packet delivery ratio of T-MAC in exchange for a small increase in power consumption. Compared to MS-MAC protocol, the proposed approach can reduce power consumption by 20–65%, and achieve slightly higher packet delivery ratio.     

Optimal DLC protocol configuration for realistic broadband fixed wireless access networks based on ATM

DLC protocols, scheduling, and multiplexing issues for broadband fixed wireless access networks based on ATM are discussed. The established DSA++ mac protocol has been developed at ComNets and has been widely applied within the German project ATMmobil. It has been a fundamental contribution to the etsi bran standardisation of HIPERLAN /2. The DSA++ is here modified to perform optimal within the fixed wireless access network environment. Therefore, realistic traffic as well as radio channel models for the respective scenarios are introduced. Simulation results are presented, showing the feasibility of the respective protocol stack for offering broadband multimedia services with reasonable quality of service. In addition to this advanced protocol approach, two systems are discussed which are currently under standardisation process. The IEEE 802.16 as well as the European hiperaccess systems are both proposed for fixed wireless access networks. Expected scenarios and applications are presented and basic requirements the standards have to fulfil are derived. As another aspect of access networks, their impact on the global information society is discussed.     

一种无线ATM网络的MAC协议

主要研究了无线ATM网络对MAC的需求，并介绍了适用于无线ATM的一种新的MAC方案。该协议支持不同类型信息传输，比如恒定比特率（CBR），可变比特率（VBR），可用比特率（ABR），未指定比特率（UBR）。另外此协议还提供了对宽带ATM主干网的无缝连接。同时也支持与ATM相关的QoS级别。对于该协议关注的各种情况的主要原理进行了讨论。     

无线ATM通信网中一种新的快速越区切换方案

本文根据地无线ATM通信网中快速越区切换问题的研究,提出了一种新的基于虚道路（VP）的快速越区切换方案,并通过建立简化的呼叫模型对该方案的切换性能进行了理论分析和比较,其结果表明,该方案的各项性能均比虚拟连接树（VCT）方案和永久虚连接（PVC）方案优越。     

Mobility management using dynamic cross-layer signaling in heterogeneous wireless networks

Wireless Networks - Vertical handover cross-layer designs lack automatic adaption with different applications. The upper layers in a cross-layer design need to be aware of the events in the lower...