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For IP-based always-on type multi-service user terminals, which may have multiple wireless interfaces, energy-efficiency is a key requirement. It is crucial to take into account the power consumption behavior and delay patterns associated with each state and transitions of the wireless devices to formulate efficient operation of multi-module terminals, especially in services where media/session handover between wireless networks are targeted. This paper investigates the power consumption pattern or behavior of some selected wireless interfaces that are good candidates for being part of the future of the multi-service user terminals. We propose a simple model for predicting energy consumption in a terminal attributed to the wireless network interfaces. We measured the actual consumption pattern to estimate the parameters of the model.

A key word describing next-generation wireless communications, so called 4G, is "seamless". As part of the e-Japan plan promoted by the Japanese government, the MIRAI (multimedia integrated network by radio access innovation) project is aiming at the development of new technologies that will enable seamless integration of various wireless access systems for practical use by 2005. First, this paper describes heterogeneous wireless networks and introduces the concept of MIRAI. The most significant feature of MIRAI is the provision of a set of signaling functions: radio-access-network discovery and selection, heterogeneous paging, and vertical handoff. These functions make it possible to offer seamless services between different wireless systems. A medium access control (MAC) protocol for basic access networks, which are dedicated wireless systems providing the signaling, is then introduced. A proof-of-concept demonstration system is also briefly introduced. The delay performances of the signaling procedures are presented.

A novel architecture for future integrated wireless network is proposed in MIRAI (Multimedia Integrated network by Radio Access Innovation) where a dedicated network takes care of the mobility functionalities of the participant wireless networks in the integration. The dedicated network, called Basic Access Network (BAN) is used primarily for wireless system discovery and paging whenever a call is initiated or a call arrives for the mobile user for any of the wireless interfaces of the user's multi-module, multi-service terminal. In this paper, we analyze a model for using the BAN channel, and associated network to perform mobility functionalities of the integrated network environment in a seamless fashion.

The 3G cellular system has infiltrated into the market and the next generation wireless system called beyond 3G is discussed at ITU-R. The beyond 3G system integrates various wireless accesses, including 3G and wireless LANs, and provides an all IP wireless solution to services that take advantage of each wireless communication of the system. Current approach to integrate wireless systems localizes wireless dependent functions and integrates all IP network using IP technologies. We propose a scalable mobile Ethernet architecture for the all IP integrated network using MAC layer technologies, such as provider bridge, RPR, and IEEE 802, and the fast vertical handover introducing common radio resource and signaling managements. We discuss network segmentation with mobility management and multicast management for the scalability of the mobile Ethernet by reducing network traffic. We evaluate the network from the viewpoint of scalability. In the evaluation, we understand that the design of the gateway switch of a segment forwarding MAC frames as an anchor point becomes effective in cases where the gateway switch of each segment cannot hold entries for all mobile terminals. We also evaluate the vertical handover as compared to the mobile IPv6 fast handover, and we understand that the fast vertical handover consumes less network resources and is flexible in having an anchor point for handover.

A key word describing next-generation wireless communications, so called 4G, is "seamless." As part of the e-Japan Plan promoted by the Japanese government, the MIRAI (Multimedia Integrated network by Radio Access Innovation) project is aiming at the development of new technologies that will enable seamless integration of various wireless access systems for practical use by 2005. First, this paper describes heterogeneous wireless networks and introduces the concept of MIRAI. The most significant feature of MIRAI is the provision of a set of signaling functions: radio-access-network discovery and selection, heterogeneous paging, and vertical handoff. These functions make it possible to offer seamless services between different wireless systems. A medium access control (MAC) protocol for basic access networks, which are dedicated wireless systems providing the signaling, is then introduced. A proof-of-concept demonstration system is also briefly introduced. The delay performances of the signaling procedures are presented.

The concept of using a separate network to carry signaling packets related to some basic mobility management functions in a heterogeneous wireless network environment has been proposed in MIRAI (multimedia integrated network by radio access innovation) architecture (see Wu, G. et al., IEEE Commun. Mag., p.126-34, 2002). In MIRAI architecture, a dedicated network takes care of the mobility functionalities of the participant wireless access networks. The dedicated network, called basic access network (BAN), is primarily used for paging whenever a call arrives for the mobile user for any of the wireless interfaces of the user's multi-service terminal, and for wireless system discovery when the user wants to initiate a call/session. We present the operation of the BAN in concert with the rest of the IP-based network, to realize a common signaling framework for heterogeneous mobility.

In MIRAI (Multimedia Integrated network by Radio Access Innovation) architecture, proposed by Wu, Havinga and Mizuno (see IEEE Commun. Mag., p.126-134, Feb. 2002), a dedicated network takes care of the mobility functionalities of the participant wireless access networks in an integrated wireless networks environment. This paper presents the dedicated network, called basic access network (BAN), which is primarily used for paging whenever a call arrives for the mobile user for any of the wireless interfaces of the user's multiservice terminal, and for wireless system discovery when the user wants to initiate a call/session. The resultant improvement in network signaling and terminal power usage efficiency is discussed. The paper also outlines the implementation issues of the air interface of this unique network, with specific focus on the system capacity, coverage and power usage.

Wireless ATM networks are motivated by an anticipated demand for wireless extensions of the integrated multimedia services. A TDMA-based wireless ATM is presented for the integration of wireless access with wired B-ISDN/ATM networks. The presented system is characterized by a reservation-based access protocol to handle diverse services and a dynamic duplexing scheme for TDD to support uplink/downlink asymmetric traffic. Resource allocation algorithms which aim at prorating the shared radio resources among ABR message traffic such as files and e-mails are also presented. Simulation results show that the equal sharing algorithm where the resources are equally shared among all mobile terminals can provide a higher average and lower variance of the throughput than the FIFO-based algorithm.

This paper presents a real-time VBR (variable bit rate) transport for next-generation multiservice personal communication networks. After discussing the characteristics of real-time VBR traffic, we propose a statistical multiplexing-based resource allocation scheme for real-time VBR traffic: "guaranteed" resources are assigned to high-priority packets, while "add-on" resources are assigned in a dynamic manner. The proposed scheme have been validated for an integrated voice/video environment, where video is encoded with a H.261-based two-layer video coder. The protocol was designed with the basic premise that there is a relatively large number of unused voice slots on average that can be used to carry "add-on" video packets. Numerical examples show that the prioritized transport under consideration can significantly improve the picture quality, and allow better utilization of wireless resources through statistical multiplexing.

For multimedia transport over the shared radio channel, best-effort service for non-real-time unit-oriented traffic would be necessary as well as a guaranteed service for real-time rate oriented traffic. This paper presents resource allocation algorithms to provide best-effort service for message traffic, whose characteristics is non-real-time and bursty. The objective of resource allocation algorithms is to utilize the shared radio resources among the message traffic for high and fair provision of throughput and efficient use of the resources without any QoS guarantee. Simulation results show that exploiting the information on the message size in the resource allocation stage brings a good improvement in the throughput performance.

The performance of microcellular mobile communication systems such as the handover priority system, the overlaying macrocell system, and handover priority with overlaying macrocell system are evaluated and compared to that of the standard microcellular system by using spectrum efficiency, grade of service, and total efficiency as evaluation criteria. The total efficiency is composed of spectrum efficiency, blocking probability, and forced termination probability, and represents the comprehensive performance of the systems. Computational results suggest that high efficiency can be achieved by applying the overlaying macrocell system when the offered traffic is low and the handover priority system when it is high. Also the combined system, i.e., handover priority with overlaying macrocell system, is expected to have higher efficiency over the wide range of the offered traffic. >

Radio resource scheduling algorithms for wireless message transport over burst-error channels are discussed. In high-speed wireless access networks, multipath fading or shadowing can cause burst packet errors that are no longer recoverable by retransmissions or forward error corrections. This has serious impact on the utilization of the wireless channel. Channel state dependent (CSD) resource scheduling algorithms were designed to utilize the channel status to improve the overall performance. Computer simulations were carried out to evaluate the scheduling algorithms in terms of average allocation plus transfer delay, average throughput, variance in throughput, and utilization of resources. Results showed that the CSD mechanism has a good effect on the scheduling algorithms, especially on the ES algorithm. Moreover, they demonstrated that CSD-ES can provide low allocation plus transfer delay, high average throughput, low variance in throughput, and efficient utilization of radio resources.

Developments in new frequency bands for wireless communications make it possible to provide a broadband channel for new services. The concept of BRAIN (broadband radio access integrated network in MM-wave band) comes about due to recent R&D activities in MM-wave communications. In order to implement integrated multimedia transmissions in a wireless environment without losing the compatibility with wired networks, the concept of wireless ATM (WATM) has been proposed. Compared with wired ATM, wireless access and mobility management are two major topics for implementation of WATM. In this paper, we focus on the topic of wireless access and propose an integrated multimedia transmission protocol, which is based on RS-ISMA (slotted idle signal multiple access with reservation), to support CBR, VBR, ABR and UBR service categories as well as to provide adaptive retransmissions for indoor systems of BRAIN.

Recently, BRAIN (broadband radio access integrated network in millimeter-wave band) is proposed as a new system concept for millimeter-wave communications. BRAIN will serve as a high-speed wireless LAN in indoor environments and as the last hop of FTTC (fiber to the curb) in outdoor environments. In the Communications Research Laboratory, an indoor LAN prototype of BRAIN including an access point and 6 remote stations was developed successfully. A wireless ATM oriented integrated transmission protocol called RS-ISMA (slotted idle signal multiple access with reservation) was implemented and thus the system can transmit multimedia traffic including voice/data/video. In this paper, we introduce in detail the system profiles of the prototype including system design, configuration, and implementation. Finally, an experimental schedule for multimedia transmission via wireless ATM is described.

In mobile communication areas, there is a demand to communicate data as well as voice information. That is, the traffic generated by computers will be given considerable weight in the future, and then a traffic imbalance between uplinks and downlinks will arise. Consequently, it seems impossible for present and future wireless networks with transmission of speech information in mind to support multimedia services because they are designed to transmit an equal quantity of traffic in each direction. This paper presents a modified packet-based TDMA/TDD scheme which aims at supporting the transmission of the integrated voice/data services. In this scheme, parameters which characterize the generation of packet sequences and represent the QOS requirements are declared before sending first the information packet for call admission control and slot allocation which can realize the support of multi-services. Furthermore, the position of the partition between the uplink and the downlink is not fixed but adaptively changeable according to the demand of duplex traffic.

This paper presents a 156 Mbps ultrahigh-speed wireless LAN in the 38 GHz millimeter (mm)-wave band. The system is the third prototype developed at the Communications Research Laboratory since 1998. Compared with the previous prototypes, the system has the following characteristics: higher speed (156 Mbps), smaller size (volume of radio transceiver < 1000 cc), larger service area (two overlapping basic service sets), and longer transmission distance (the protocol can support a distance of more than two hundred meters). The development is focused on the physical layer and data link control layer, and thus a GMSK-based mm-wave transceiver and an enhanced RS-ISMA (reservation-based slotted idle signal multiple access) are the key development points. This paper covers the prototype system's design, configuration, and implementation.

The concentration and affinity to concanavalin A (ConA) of plasma alpha 1-acid glycoprotein (AGP) and AGP levels in extracts of liver tissues were investigated in specific-pathogen-free chickens infected with the highly virulent HPS-2 strain or virulent reference GBF-1 strain of infectious bursal disease virus. The plasma AGP value in uninfected control 3- to 7-wk-old chickens was 161.8 +/- 25.8 micrograms/ml (mean +/- SD), and ConA-unreactive and ConA-reactive AGP comprised 47% and 63% of total AGP. Increases in AGP levels in plasma and liver extracts were observed in both the HPS-2 and the GBF-1 groups, although albumin levels decreased. The plasma AGP values were higher in the HPS-2 group than in the GBF-1 group through the experimental period. In the HPS-2 group, ConA-reactive AGP reached levels 6.8-fold greater than control values and comprised 80% of total AGP at 4 days post-inoculation. In the lipopolysaccharide group, a great increase in ConA-reactive AGP was observed.

SUMMARY. Thymic lesions were investigated in specific-pathogen-free chickens infected with the highly virulent HPS-2 strain or virulent reference GBF-1 strain of infectious bursal disease virus (IBDV). Both viruses induced follicular lymphoid necrosis and depletion in the bursa, as well as thymic lesions. However, cortical lymphocyte condensation and depletion in the thymus were more prominent in the HPS-2 group than in the GBF-1 group. Electronmicroscopically, alterations of cortical lymphocytes were characterized by nuclear disintegration resembling apoptosis. Immunohistologically, the virus-antigen-positive epithelial reticular cells in the medulla were more extensive in the HPS-2 group. These results suggest that HPS-2 IBDV persists in the thymic medulla and that cortical lymphocyte depletion is caused by virus-induced apoptosis.

An out-of-band basic access signaling (BAS) protocol is introduced for use in heterogeneous wireless networks. The BAS protocol enables a mobile terminal to communicate with an agent in a fixed network through any radio access network (RAN) chosen by the user as the basic access network (BAN). The agent uses the information on the location of mobile terminals and on the availability of RANs to decide which RAN to use, taking the user's preferences into account. This protocol was implemented in a demonstration system using existing radio systems and the standard mobile IP protocol. The separation of the signaling path from the data paths was found to save energy and to facilitate handover between RANs.