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Byline: Mahmoud H. Ismail (1), Hebat-Allah M. Mourad (1), Magdi M. S. El-Soudani (1) Keywords: channel estimation; link adaptation; Rayleigh fading; throughput maximization Abstract: Link Adaptation (LA) has been proposed in the literature as a means of increasing the throughput obtained by each user in wireless communication systems. Due to its significant simplicity, LA has even been adopted as the standard adaptive coding technique for the next generation mobile communication system known as EDGE. In this paper, we present a novel link adaptation technique, valid for use in the case of Rayleigh fading wireless channels. The new technique is based on the blind channel estimation algorithm usually used for combating inter-symbol interference (ISI). The algorithm is presented and its efficiency in providing the maximum available throughput is illustrated by means of computer simulations. Author Affiliation: (1) Department of Electronics and Electrical Communications, Faculty of Engineering, Cairo University, Giza, Egypt Article History: Registration Date: 01/01/2004

Byline: Antonis E. Markopoulos (1), Panagiotis Pissaris (1), Sofoklis Kyriazakos (1), Efstathios D. Sykas (1) Keywords: handover optimization; location aided network optimization; ping-pong; interference; power allocation; GSM; UMTS Abstract: Mobile world's rapid growth has spurred development of new protocols and new algorithms to meet changing operation requirements such as mobile networking, and quality-of-service support. A key requirement in the bearer capabilities is the handover. The freedom to be able to make and receive calls anywhere, at any time, creating a totally new dimension in human communications has frequently been advertised as the main advantage of new wireless systems. Handovers are a key concept in providing this mobility. It makes it possible for a user to travel from one cell to another while having a seamless connection. Network operators give emphasis to optimize handover, since it is strongly related to dropped calls, network overload and subsequently users' criticism. The ability of a cellular network to perform efficient handovers is crucial to offer attractive services as real-time applications or streaming media as planned in third generation networks. Since signal propagation and pathloss are complex in nature, we can expect unnecessary and wrong handoff executions. Both UMTS and those of the second generation (GSM) systems will require redefined handoff algorithms of active connections as the smooth mobility support and continuous connection are essential issues for obtaining high performance and increasing user satisfaction. In this paper we present a set of intelligent algorithms using the mobile terminal (MT) location information and area awareness to assist safe handoff decisions. The implemented algorithms are validated by means of cellular network simulators that clearly show the impact of these techniques to major system performance metrics. Author Affiliation: (1) School of Electrical and Computer Engineering, National Technical University of Athens, Telecommunications Laboratory, 9 Heroon Polytechneiou Street, Zographou, 15773, Athens, Greece Article History: Registration Date: 20/12/2004

Byline: Craig Gentry (1), Zulfikar Ramzan (1) Keywords: cryptography; provable security Abstract: Many attempts to secure mobile wireless systems have failed abysmally. Notable examples include 802.11 WEP, as well as major cellular phone standards such as TDMA, CDMA, and GSM. The attacks typically result from the correct use of a bad cryptographic primitive or the incorrect use of a good one. By designing provably secure algorithms and protocols, we not only minimize the time required to gain confidence in the security of a system, but we virtually eliminate the possibility of a cryptographic vulnerability. Unfortunately, the concept of 'provable securit' is often misunderstood. In this survey paper, we state precisely what provable security is and is not, and describe the benefits of the approach. Author Affiliation: (1) DoCoMo Communications Laboratories, Inc., San Jose, CA, U.S.A. Article History: Registration Date: 29/12/2004

Byline: Walter Weigel (1) Keywords: mobile radio communications; systems beyond third generation; WLAN; IP Abstract: This paper gives an overview of the envisaged requirements and building blocks for mobile communication systems beyond 3G (B3G). It analyzes the drivers for such a system taking into consideration the key areas 'services', 'network' and 'radio' and presents possible corner stones for an appropriate radio interface. Hence it gives an overview how a future system B3G may look like. Author Affiliation: (1) Siemens AG, Information &amp Communication Mobile Networks, St.-Martin-Str, 76, D-81541, Munich, Germany. walter.weigel@siemens.com Article History: Registration Date: 05/10/2004

The tradeoff between mandated standards and market driven standards in the European and North American wireless telecommunications industry is discussed. The institutional background on the development of 1G - 2G and the implications of the results on the 3G standards are stated.

Byline: Weifeng Su (1), Xiang-Gen Xia (1) Keywords: diversity; (generalized) complex orthogonal designs; Hurwitz theorem; space-time block codes; wireless communications Abstract: Space-time block codes from orthogonal designs recently proposed by Alamouti, and Tarokh-Jafarkhani-Calderbank have attracted considerable attention due to the fast maximum-likelihood (ML) decoding and the full diversity. There are two classes of space-time block codes from orthogonal designs. One class consists of those from real orthogonal designs for real signal constellations which have been well developed in the mathematics literature. The other class consists of those from complex orthogonal designs for complex constellations for high data rates, which are not well developed as the real orthogonal designs. Since orthogonal designs can be traced back to decades, if not centuries, ago and have recently invoked considerable interests in multi-antenna wireless communications, one of the goals of this paper is toprovide a tutorial on both historical and most recent resultson complex orthogonal designs. For space-time block codes from both real and (generalized) complex orthogonal designs (GCODs) with or without linear processing, Tarokh, Jafarkhani and Calderbank showed that their rates cannot be greater than 1. While the maximum rate 1 can be reachedfor real orthogonal designs for any number of transmit antennas from the Hurwitz--Radon constructive theory, Liang and Xia recentlyshowed that rate 1 for the GCODs (square or non-square size) with linear processing is not reachable for more than two transmit antennas.For GCODs of square size, the designs with the maximum rates have been known, which are related to the Hurwitz theorem.In this paper, We briefly review these results and give a simple and intuitive interpretation of the realization. For GCODs without linear processing (square or non-square size), we prove that the rates cannot be greater than 3/4 for more than two transmit antennas. Author Affiliation: (1) Department of Electrical and Computer Engineering, University of Delaware, Newark, DE, 19716, U.S.A. Article History: Registration Date: 11/10/2004

The high-speed downlink packet access (HSDPA) system provides an efficient, cost-effective means of migrating from Universal Mobile Telecommunications System (UMTS) Rel99/4 to high-speed data-capable networks.

With the rapid development of Global Positioning System (GPS) technology and its applications, synchronization between terminals in mobile ad hoc environments becomes feasible at a low cost. Thus, slotted-channel-based medium access control (MAC) schemes like time division multiple access (TDMA) also become interesting for mobile ad hoc networks (MANETs). In this paper, we extend the classical centralized and slotted packet reservation multiple access (PRMA) scheme to a simple distributed PRMA (D-PRMA) as an MAC scheme for MANETs, with emphasis on voice application support. The major efforts of D-PRMA include 1) a simple slot reservation mechanism for voice traffic at the level of 'talkspurt' without relying on any central entity and 2) a simple solution for the hidden and exposed terminal problems uniquely present in wireless ad hoc environments. The performance of D-PRMA has been investigated by analysis and computer simulations in comparison with IEEE 802.11. The results show that D-PRMA is much more suitable than IEEE 802.11 for voice application. Index Terms--Distributed packet reservation multiple access (D-PRMA), Global Positioning System (GPS), medium access control (MAC), mobile ad hoc networks (MANETs), packet reservation multiple access (PRMA).

Byline: Thomas Toftegaard Nielsen (1) Keywords: wireless Internet; mobile data; IPv6; GPRS; GSM; GPRS; UMTS; Cellular IP; IP RAN; Mobile IP; QoS; IPSec Abstract: The functionalities of the next generation Internet protocol, IPv6, havebecome increasingly interesting due to the current merging of the traditionalcellular mobile communications and the traditional data-communications intothe future wireless systems, as e.g., UMTS. IPv6 provides several enhancedfunctionalities requested for the future mobile systems. In this article thelargest advantages in relation to mobile systems are presented. Variousaspects of introducing IP throughout the entire mobile network (core, accessand termainals) are also presented along with an illustration of the abilitiesof the future wireless network. Author Affiliation: (1) Ericsson Telebit, Denmark Article History: Registration Date: 04/10/2004

Dedicated short-range communication (DSRC) and 4G-LTE are two widely used candidate schemes for Connected Vehicle (CV) applications. It is thus of great necessity to compare these two most viable communication standards and clarify which one can meet the requirements of most V2X scenarios with respect to road safety, traffic efficiency, and infotainment. To the best of our knowledge, almost all the existing studies on comparing the feasibility of DRSC or LTE in V2X applications use software-based simulations, which may not represent realistic constraints. In this paper, a Connected Vehicle test-bed is established, which integrates the DSRC roadside units, 4G-LTE cellular communication stations, and vehicular on-board terminals. Three Connected Vehicle application scenarios are set as Collision Avoidance, Traffic Text Message Broadcast, and Multimedia File Download, respectively. A software tool is developed to record GPS positions/velocities of the test vehicles and record certain wireless communication performance indicators. The experiments have been carried out under different conditions. According to our results, 4G-LTE is more preferred for the nonsafety applications, such as traffic information transmission, file download, or Internet accessing, which does not necessarily require the high-speed real-time communication, while for the safety applications, such as Collision Avoidance or electronic traffic sign, DSRC outperforms the 4G-LTE., 1. Introduction In 2011, the US Department of Transportation (US DOT) announced plans to support the introduction of vehicle-to-vehicle (V2V) communication among light-duty vehicles in the USA, commonly known as [...]

This paper proposes a medium-access control (MAC) protocol for integrated voice/data services in local wireless communications. The proposed protocol is a hybrid of R-Aloha and Aloha reservation adapted to local wireless environment. In the proposed hybrid Aloha-reservation/R-Aloha (HAR) protocol, data messages are transmitted using Aloha-reservation protocol, whereas voice packets are transmitted according to R-Aloha on the channel assigned using Aloha reservation. The performance of the lIAR protocol is analyzed by computer simulation. Simulation results prove that the HAR protocol is appropriate as a protocol for integrated services wireless networks in which computer data is major traffic and voice traffic coexists. Index Terms - Local wireless communications, medium-access control (MAC), voice/data-integrated services.