Group-Based Authentication and Key Agreement

This paper presents an authentication and key agreement protocol to streamline communication activities for a group of mobile stations (MSs) roaming from the same home network (HN) to a serving network (SN). In such a roaming scenario, conventional schemes require the SN to interact with the HN for authenticating respective MSs, at the cost of repeated message exchanges and communication delay. Instead, in our design, when the first MS of a group visits, the SN performs full authentication with the concerned HN and thereby obtains authentication information for the MS and other members. Thus when any other MS of the same group visits, the SN can authenticate locally without subsequent involvement of the HN, so as to simplify protocol operations. We will show that our scheme does not trade performance for security and robustness to the extent that security requirements are unduly weakened. Both qualitative and quantitative discussions indicate that our proposed scheme lends itself to pragmatic settings.     

Design and Performance Study for a Mobility Management Mechanism (WMM) Using Location Cache for Wireless Mesh Networks

Wireless mesh networks (WMNs) have emerged as one of the major technologies for 4G high-speed mobile networks. In a WMN, a mesh backhaul connects the WMN with the Internet, and mesh access points (MAPs) provide wireless network access service to mobile stations (MSs). The MAPs are stationary and connected through the wireless mesh links. Due to MS mobility in WMNs, mobility management (MM) is required to efficiently and correctly route the packets to MSs. We propose an MM mechanism named Wireless mesh Mobility Management (WMM). The WMM adopts the location cache approach, where mesh backhaul and MAPs (referred to as mesh nodes (MNs)) cache the MS's location information while routing the data for the MS. The MM is exercised when MNs route the packets. We implement the WMM and conduct an analytical model and simulation experiments to investigate the performance of WMM. We compare the signaling and routing cost between WMM and other existing MM protocols. Our study shows that WMM has light signaling overhead and low implementation cost.     

Macrodiversity power control in hierarchical CDMA cellular systems

Hierarchical code division multiple access (CDMA) cellular systems, consisting of macrocells with underlying microcells, are studied. We seek power control schemes which will allow both hierarchical layers to share the same spectrum. For the reverse link, hierarchical maximal ratio combining (HMRC) is applied where each mobile station (MSs) is received and coherently combined by base stations (BSs) in both layers. For the forward link, selective transmit diversity (STD) is applied where each BS provides multiple transmit paths for MSs to choose. We show that both HMRC and STD are effective in hierarchical CDMA architectures. We conclude that hierarchical architectures are a viable solution for improving CDMA cellular system capacity, and a significant performance gain can be achieved without assigning disjoint spectrum between the layers, by utilizing macrodiversity schemes such as HMRC and STD     

Bandwidth-reservation scheme based on road information for next-generation cellular networks

Channel-reservation techniques have been widely studied in cellular networks in order to meet the desired quality-of-service requirements. In this paper, a distributed predictive channel-reservation scheme, called the road-map-based channel-reservation scheme (RMCR), and a call-admission-control algorithm are proposed. The goal is to reduce the handoff-dropping probability and to improve the bandwidth utilization. In the RMCR scheme, we assume that base stations (BSs) are equipped with road-map information and that mobile stations (MSs) are equipped with global positioning systems (GPS) devices. MSs periodically report their GPS location information to their BSs. Based on the location information of the MSs at two consecutive epochs, the BSs estimate the speed and moving direction of the MSs. Furthermore, the BSs estimate the probability that the MSs will enter the neighboring cells based on their velocity and the road-map information stored in the BSs. The BSs then compute the amount of bandwidth to be reserved, based on such estimation. With the road-map information, the BSs can make a more-accurate prediction on the user's mobility and, hence, reduce unnecessary bandwidth reservation. Simulation results show that RMCR is capable of keeping the handoff-dropping probability low and allocating bandwidth to new/handoff calls efficiently. We also show that RMCR is robust with respect to system parameters such as user's speed, the density of roads, the accuracy of mobility measurement, and so on.     

Method for positioning GSM mobile stations using absolute timedelay measurements

A trilateration based method for locating mobile stations (MSs) in GSM cellular communication network is proposed. Measurements are processed with an extended Kalman filter (EKF), in order to track MSs and to establish their position. An analytical study of positioning accuracy is also developed     

Mean velocity estimation of mobile stations by spatial correlation of channels in cellular systems

We propose a velocity estimation scheme for mobile stations (MSs) in cellular communication systems that uses the azimuth spread (AS), delay spread (DS), and shadow fading of MSs. Due to the fact that the AS, DS, and shadow fading are correlated in the spatial domain, the variation of the AS, DS, and shadow fading of an MS is related to its velocity. And, we also consider the variation of velocity which was not considered in previous velocity estimation studies. Through analysis and numerical results, we show that we can estimate the velocity of an MS with lower estimation error compared to previous estimation schemes, despite of measurement error.     

Markov mobility model and registration area optimization in cellular networks

In cellular communication systems, in order for a network to keep track of inactive mobile stations (MSs), each inactive MS has to update its location from time to time, called location registration. To lighten the task of tracking inactive MSs, the network divides its cells into groups, called location areas (LAs) and tracks inactive MSs at the LA level: an inactive MS sends a registration message to the network to update its location only when it travels to a new LA. Obviously, the performance of a location area design depends on network traffic and the mobility of MSs. In the paper, we propose a general Markov mobility model for MSs in cellular networks, provide a procedure to automatically estimate the system parameters according to the network traffic, derive the performance of LA design, and provide a clustering algorithm to optimize LA designs. A numerical example is provided to show the effectiveness of the proposed procedures. Copyright © 2009 John Wiley & Sons, Ltd.     

iSMS: an integration platform for short message service and IPnetworks

This article describes iSMS, a platform that integrates IP networks with the short message service in mobile telephone systems. iSMS provides a generic gateway for creating and hosting wireless data services for mobile stations. Our approach does not require any modification to the mobile telephone system architecture. The iSMS system can be quickly developed and operated by a third party or end user without involvement of mobile equipment manufacturers and telecom operators. Based on the iSMS platform, we illustrate services such as e-mail delivery/forwarding, Web access (e.g., stock and train schedule query) and handset music services. The iSMS platform and the services have been implemented for GSM networks. With iSMS, users are able to use standard GSM handsets to access wireless Internet services, while other approaches like the Wireless Application Protocol and SIM Toolkit services require function-enabled MSs     

A Mixed Mechanism Mutual Authentication Protocol for TETRA

1 Introduction TETRAsystemis a unified standard-based open sys-tem designed by European Telecommunications Stan-dards Institute(ETSI) in association with user organiza-tions, manufacturers ,testing and government authori-ties to satisfythe mobile communicationrequirements ofthe specialized institutions in all the European coun-tries .[1 ~4]A TETRAsystem supports many functionsonthe security field, which include authentication,airinterface encryption and end-to-end encryption.The au-then…     

On the Performance of Downlink MIMO Systems with Different Operating Frequencies

Currently, multiple input multiple output (MIMO) systems are adopted in many current cellular systems such as Long Term Evolution or 802.16 m. However, the performance of MIMO systems is greatly dependent on system parameters and environments. In this study, we evaluate the performance of downlink MIMO systems to find out which operating frequency among 800 MHz, 2.5 GHz, and 3.5 GHz is the best for next generation MIMO cellular systems. For each operating frequency, we consider the most prevalent types of mobile stations (MSs), the USB type, PDA type, and laptop type, which experience different mutual coupling between neighbor antenna elements mainly caused by the miniaturization of MSs. System simulation results show that regardless of the MS type, average and edge throughputs are almost the same for all the considered frequencies in the interference-limited environment. In contrast, the operating frequency of 800 MHz at which the mobile type with a larger antenna spacing has spatial multiplexing gain, provides the best average and edge throughputs in noise limited system environments.     

Design and performance analysis for data transmission in GSM/GPRSsystem with voice activity detection

To efficiently utilize the bandwidth of cellular mobile systems and offer service of high quality to both voice and data users, we propose a protocol to integrate packet-switched data traffic into current time-division multiple-access (TDMA)-type circuit-switched digital voice systems. We analyze the performance of the proposed system, which transmits data packets in the silent periods of a conversation with voice activity detection and adapts itself to the GSM/GPRS system, which uses the idle channels to provide data services. We show that the proposed protocol can increase the bandwidth utilization efficiency and improve the throughput/delay performance of the data transmission while minimizing the impact on the current GSM/GPRS service     

On the Performance of Cellular Two-Way Relay Systems with Analog Network Coding and Multiuser Diversity

We consider a cellular two-way relaying system in which a multi-antenna base station (BS) communicates bidirectionally with one of several single-antenna mobile stations (MSs) via a single-antenna relay using analog network coding. We employ MS selection coupled with beamforming at the BS so as to maximize the end-to-end signal-to-noise ratios. In the considered system, the target rates at the sources can generally be different owing to the asymmetric traffic flow in opposite directions. With such a general setup, we perform an overall system outage probability analysis over Rayleigh fading channels. For more insights, we derive a closed-form asymptotic expression for overall outage probability and an upper bound expression for ergodic sum-rate of the system. Based on these expressions, we show that the system achieves a performance gain, and a diversity order of minimum of the number of BS antennas and the number of MSs. Moreover, we address the problem of optimization of relay location in order to minimize the overall system outage under asymmetric traffic conditions. Finally, we provide numerical and simulation results to corroborate the theoretical analysis and the advantages offered by the proposed scheme.     

On the impact of the soft handoff threshold and the maximum size of the active group on resource allocation and outage probability in the UMTS system

We study the effect of two control parameters of the universal mobile telecommunication system handoff algorithm on resource allocation and the outage probability of the forward link. We thereby provide information on the effect of the parameters on the probability distributions of the number of base stations (BSs) supporting a mobile station (MS), the number of MSs supported by a single BS (per carrier), and the maximal cell size, subject to a given probability of downlink outage on the cell boundary. Denoting the set of BSs supporting an MS in soft handoff as the active group, the first parameter n/sub A/ is the maximum allowed size of the active group. The second, denoted /spl tau/, is the upper limit on the difference between the local mean received power from the dominant BS and that from any other member of the active group (in decibels), where the term "dominant" refers to the BS with the lowest path loss to the MS. We assume that the MS is equipped with a Rake receiver capable of performing "maximal ratio combining" of the signals it receives from the transmitting BSs. We present general analytical derivations along with results derived for specific situations through simulations and numerical integration.     

Resource Allocation Schemes for the Heterogeneous OFDMA System with Multiple Ad Hoc Relays

In this paper, we present a heterogeneous network framework involved an orthogonal frequency division multiple access (OFDMA) network with an out-of-band Ad Hoc network, which maybe a promising architectural upgrade and has not been studied so far. In the heterogeneous system, the mobile stations (MSs) are dual-mode with both cellular OFDMA and Ad Hoc radios. And MSs communicate with the base station by cellular OFDMA mode, while they communicate with each other by Ad Hoc mode. An active MS can choose multiple inactive MSs as its relay stations (RSs). And each RS operates in a full duplex mode, that is, it can receive data through Ad Hoc network in the first hop and transmit data through the OFDMA network in the second hop, simultaneously. Based on this heterogeneous system, the problem of joint relay selection, subcarrier and power allocation with the objective of maximizing the system capacity under individual rate and transmit power constraints is addressed. We propose a dual-based resource allocation scheme to solve the problem fairly and efficiently, and then we propose a fully distributed resource allocation scheme to decrease the computational complexity. Simulation results show that the performance of the proposed dual-based resource allocation scheme, in terms of the system capacity and the outage probability, is better than that of the fully distributed resource allocation scheme. However, the performance improvement is at the expense of a high computational complexity.     

Introduction of the Asymmetric Cryptography in GSM,GPRS, UMTS,and Its Public Key Infrastructure Integration

The logic ruling the user and network authentication as well as the data ciphering in the GSM architecture is characterized, regarding the transferring of the parameters employed in these processes, by transactions between three nodes of the system, that is the MS, actually the SIM, the visited MSC/VLR, and the AuC, which is attached to the HLR in most cases. The GPRS and the UMTS architecture carry the heritage of the GSM's philosophy regarding the user/network authentication and the data ciphering. So, the corresponding three nodes (MS, VLR, and HLR) of these systems are involved as well in the authentication and data ciphering procedures. Moreover, the methods of the conventional cryptography have been adopted by all three systems. This paper describes in brief the subscriber authentication and data ciphering, as they are recommended by the Specifications for all three aforementioned systems. Based on what the specifications define, we pinpoint the vulnerable points of the systems, exposed to third party attacks, and propose asymmetric cryptography procedures for their coverage, consisting of the introduction of public–private key pairs for the transactions between the VLR-HLR, as well as the MS-VLR. On the other hand, the nature of the services constituting a Public Key Infrastructure (PKI) renders the telecommunication operators the main candidates for the development of PKIs fully or partially fledged. The private–public key pair, stored by the PLMN operator in the SIM, for the GSM/GPRS case, or in the USIM for the UMTS case and created to deal initially with internal system functions, can easily be extended, adopted and employed in secure e/m-transactions, if bound to a digital certificate, in the case the PLMN operator supports PKI services as well.     

一种混合机制的TETRA双向鉴权协议

该文详细分析了TETRA系统移动台和网络之间的鉴权协议,分析表明采用共享秘密的挑战应答协议存在若干缺陷:(1)当无法保证访问位置寄存器和归属位置寄存器之间的通信安全时会产生对已知明文攻击的开放性;(2)网络规模较大时,在网络端难于保存和维护大量的鉴权密钥。在理论分析的基础上该文给出了一种基于身份公钥的网络端对移动台和基于哈希链的移动台对网络端的鉴权协议,所提出的协议可以有效弥补上述缺陷。     

Reduced-Complexity Belief Propagation for System-Wide MUD in the Uplink of Cellular Networks

System-wide multiuser detection (MUD), in which all base stations (BSs) of a cellular system cooperate to detect the data of all mobile stations (MSs), has much promise. However, little is known at present about practical techniques or their performance. An attractive method is belief propagation (BP), with message exchange between nearby cooperating BSs over a backbone landline network, but its performance is known only for a greatly simplified network model and its computation load grows exponentially with the number of interfering MS symbols at each BS. In this paper, we present a reduced complexity variation of BP (RCBP) and show that its performance is close to or identical to that of BP in the simplified network. We also observe excellent performance by iterative multiuser detection and decoding of low-density parity check codes (LDPC). Furthermore, we examine RCBP performance in a realistic wireless network model, with path loss, shadowing, fading and power control. These results, though poorer than those of the simplified network, show that system-wide MUD with cooperating BSs provides great improvement compared with conventional systems.     

QoS Handover Management in LEO/MEO Satellite Systems

Low Earth Orbit (LEO) satellite networks are foreseen to complement terrestrial networks in future global mobile networks. Although space segment topology of a LEO network is characterized by periodic variations, connections of mobile stations (MSs) to the satellite backbone network alter stochastically. As a result the quality of service delivered to users may degrade. Different procedures have been proposed either as part of a resource allocation mechanism or as part of an end-to-end routing protocol to manage transitions of MSs from one satellite to another (handover). All of these techniques are based on the prioritization of requested handovers to ease network operation and therefore enhance provision of service. This paper proposes a new handover procedure that exploits all geometric characteristics of a satellite-to-MS connection to provide an equable handover in systems incorporating onboard processing satellites. Its performance is evaluated by simulations for a variety of satellite constellations to prove its general applicability. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fixed power allocation with nulling for TDD-based cellular uplink

We propose two fixed power allocation schemes with nulling (FPA-N1 and FPA-N2) for time division duplex (TDD) based cellular uplink according to the location of mobile stations (MSs). In the FPA-N1 scheme, MSs located near a base station (BS) do not transmit data when the wireless channels between the MSs and their home cell BS experience deep fading. In the FPA-N2 scheme, MSs located near cell boundaries do not transmit data when the wireless channels between the MSs and neighboring cell BSs cause high interference channel gain because, in this case, their data transmission may induce large interference to neighboring cells. Numerical results show that the proposed power allocation scheme improves the uplink capacity in cellular networks.     

室内单个UWB设备对GSM系统的干扰分析

根据FCC频谱模板,分析了室内单个UWB设备工作时的发射信号对GSM通信系统(包括GSM900和DCS1800)的电磁干扰;仿真了UWB设备和GSM移动台间距离对GSMMS接收信噪比的影响。其中UWB干扰信号对GSM900的干扰在信噪比冗余度内。而对DCS1800的干扰远大于GSM900,当二者距离小于25cm时,降到9dB以下,通信质量严重下降,链路会因此中断。