Balog Károly (2001)

WIRELESS DATA COMMUNICATIONS IN THE 21ST CENTURY

ABSTRACT

This article presents the current and future wireless telecommunications and increasingly popular wireless-data communications, and then explore the key technologies and fundamental elements, of near-future commercial and military data communications. The combination of wireless and data networking will result in a new form of computational paradigm which is more communication-centric than any computer network seen before.

I briefly discuss related wireless network models, namely mobile ad hoc networks, cellular networks, and a number of short range wireless local area networks.

INTRODUCTION

The Information Warfare one of the recently new and dynamically expanding warfare method, which activity trend to information superiority. In peace time the information warfare proceed with conventional instrument beside informational, technical and computers equipment and telecommunications intelligence equipment.

The 21st century forces will be apply to most up to date informations tele and data-communications technique in widespread. That’s all the more reason we must know definitely the continuously changing electromagnetic environment, and the creator of the technological background. The up to date wireless communication and data communications, are not “COMINT (Communications Intelligence) friendly”, and quite a number of question bring up in front of COMINT. For that very reason we must know the various already existing and the under projecting telecommunications systems, technology, trends, and standards.

THE CIVIL AND THE MILITARY COMMUNICATIONS

In the present geopolitical context, the missions of modern armies have dramatically changed, and along with them, their communication and data communications requirements. Because more and more intelligent information and command systems and ever more sophisticated weapon systems are encountered in the battlefield. Tactical networks have become the indispensable means for general coordination, in real time, of all the resources deployed by modern armed forces.

On the national territory, Armies need to rely on a private, secure network, protected against all kinds of intrusion. The modern armed forces adapted tactical and infrastructure communication networks, enabling the State and military authorities to cope with all types of situations in the best conditions as possible, and the digital battlefield enters the era of multimedia.

These networks are based upon the latest civil technologies and offer a wide range of interfaces compliant with the most generally used civil and military standards, so as to permit the use of commercial equipment.

THE NETWORK PARADIGM OF THE 21ST CENTURY

Due to the explosion in use of the Internet, it is expected that a variety of services will be provided through the communications network in the 21st century. In addition, IP development is moving to provide mobile IP. Therefore, we propose an integrated fixed/mobile network that treats all terminals as mobile terminals. The consequence the network paradigm shift is that mobile access will become a dominant technology used to access services on a network.[1]

Today’s change in telecommunications is primarily driven by new data-communications technologies.

The structure of datacom network is inherently different from that of a telecom network. /figure 1./ It is important to understand these differences in order to make efficient use of the new technologies. [2]

A generic telecom network structure is as follows: a resourceful high-performance core in the network, then less advanced equipment the closer we get to the periphery of the network. This is a core-centric structure. In a telecom network we typically have thin clients.

A datacom network, on the other hand, is structured the other way around. Here we typically have fat clients – the connected computers. The basic component in the network is the LAN. But when interconnecting LANs into a datacom network, performance gets more expensive. This means that the periphery, from both the performance and intelligence points of view, is the

strong part of the network. Thus, here we have the opposite type of network – periphery-centric.

Telecom and datacom technologies different network structures

Telecom and datacom technologies Telecom and datacom technologies different network structuresdifferent network structures

Figure 1. The different Network structures

The following I shortly outlined the present and future civil second and third-generations wireless communications and data communications systems.

THE PRESENT AND THE FUTURE WIRELESS COMMUNICATIONS SYSTEMS

2G + SYSTEMS (2,5 G)

Present cellular systems are based on TDMA (Time Division Multiple Access) and CDMA (Code Division Multiple Access) technologies, and provide packet data transmission at low rates. GSM GPRS (General Packet Radio Service) is a TDMA and IS-95B a CDMA-based CDPD (Cellular Digital Packet Data) system. Packet mode data capabilities of these networks represent several improvements over 2G cellular networks: high-speed wireless transfers between

LAN

StrongholdStronghold

LAN

DatacomTelecom

mobile units, the Internet and other packet-data networks. Higher-capacity transmission is achieved with multislot mode in TDMA and multiple codes in CDMA-based system. In some cases, a higher level modulation format is used to increase the rate of transmission.

The GPRS and CDPD are expected to transmit data at speeds comparable to today's ISDN lines, which run at several hundred kilobytes per second.

The evolution to higher data rates and more advanced services occurs in two steps. The first step is the emergence of second plus systems in which second-generation systems such as GSM, is extended to provide high-speed data communications without changing the air interface or by using improved coding technique. The second step is to provide higher capacity, data rates, and multimedia services.

3G SYSTEMS

The third generations mobile communications systems, the international IMT2000 (International Mobile Telecommunication 2000) and the European UMTS (Universal Mobile Telecommunications System) can provide higher capacity and a one magnitude better bit error rate, allowing data communication using a mobile system to be much better quality than at present.

The main characteristic of third-generation systems is the convergence of mobile and multimedia services up to two Megabit per second driven by the explosion of the Internet. The IMT2000 “family” of standards within this family the UMTS, sponsored by the ETSI (European Telecommunications Standards Institute) jointly with many other standards organizations worldwide, is the main focus of the European Community efforts.

The UMTS is “universal” in three ways: • It is designed to provide universal geographical coverage. A terrestrial

(T-UMTS) component and a satellite (S-UMTS) component have been defined to achieve this goal.

• It is designed to offer costumers universal services beyond voice and low-data-rates ones.

• It is designed to work in universal environments, from outdoor to indoor, and for universal requirements, from fixed to vehicular.

While waiting for IMT-2000 and UMTS implementation, COMINT agencies

can contemplate challenging cell-phone technologies being introduced today. They include cell-phone connectivity to the Internet or intranets, the emergence of multimedia wireless devices and the development of Bluetooth. [5]

And next I briefly discuss related wireless network models, namely cellular networks, mobile ad hoc networks, and a number of short range wireless local area networks, because this is the most important technologies the future battlefield communications.

MOBILE NETWORK TYPES

According to the 802.11 study group of the IEEE (Institute of Electrical and Electronics Engineers), the wireless networks can be classified in independent (ad hoc) or infrastructure.

INFRASTRUCTURE NETWORKS

Infrastructure networks are those in which the Mobile Host(MH) is in direct contact with a Mobility Support Station (MSS) in the fixed network. This MSS is normally linked to a fixed network of high speed. /figure 2./

Figure 2. The sample of cellular network

In this type of wireless network, all the communication is performed by the MSS. The functioning of this type of mobile network is similar to the one of cellular telephony, where all the communication must necessarily pass by the

central, even if the telephones are in a position that they could, eventually, to communicate between themselves directly.

AD HOC NETWORKS

The mobile ad hoc networks /MANET/communication is performed directly between a portable computational device such as computers, laptops, palmtops, cellular telephones or even through different types of Personal Digital Assistants. /figure 3./

Figure 3 .The sample of ad-hoc network

The mobile computation has many applications in situations where an infrastructure of fixed network does not exist (eg. battlefield) or its implantation is not interesting and, also, for the communication between "wearable computers". The users of this environment access independent by of where they are located and, the most important, independent by of location changes, providing mobility to the users. This is a new computational paradigm. In this way, the mobile computation extends the traditional concept of distributed computation. This is possible due to the wireless communication, that eliminates the necessity of the user to remain itself connected to one fixed infrastructure, generally static.

On traditional networks, like the Internet, the routing is based on the address of the node. In mobile networks the main problem is the location of the nodes. They do not have a fixed position and can move themselves freely. To determine the accurate node position is not simple.

Various wireless networks mapped to two independent aspects of ad-hoc networking: the level of centralized control (horizontal), and the use of radio multihopping (vertical). /figure 4./

Figure 4. The wireless network mapped two aspect

In a MANET a path between two computers can be formed by several hops through one, or more, computers in the network, as seen in figure 5. The circles demonstrate the radius of communication of the mobile units. In this way the messages of the A node for the D node for example, must pass, by the nodes B and C to arrive at the D node. One of the basic problems in an ad hoc network is to determine and to keep the paths, since the mobility of a computer can cause changes in the topology. Many routing algorithms for ad hoc networks had been considered in literature. These algorithms differ in the form where new paths are determined and how the existing ones are modified, when necessary.

Manet applications and challenges Military applications: Packet radio networks, ad-hoc wireless networks

have an important role to play in military applications. Soldiers equipped with

multi-mode mobile communicators can now communicate in an ad-hoc manner, and changing tactical information, without the need for fixed wireless base stations. In addition, small vehicular devices equipped with audio sensors and cameras can be deployed at targeted regions to collect important location and environmental information which will be communicated back to a processing node via ad-hoc mobile communications. Ad-hoc mobile communication is provides alternate communication paths without reliance on ground- or space-based communication infrastructures.

CA D

B

Figure 5. The single and multihop ad-hoc network types

Commercial scenarios for ad-hoc wireless networks include:

• conferences/meetings/lectures • Home networking Home RF • emergency services, and law enforcement • Personal area network /PAN/ and Bluetooth • Embedded computing applications • Automotive, and other envisioned applications

People today attend meetings and conferences with their laptops, palmtops

and notebooks. It is therefore attractive to have instant network formation, in addition to file and information sharing without the presence of fixed base

stations and systems administrators. A presenter can multicast slides and audio to intended recipients. Attendees can ask questions and interact on a commonly-shared white board. Ad-hoc mobile communication is particularly useful in relaying information (status, situation awareness, etc.) via data, video and/or voice from one rescue team member to another over a small handheld or wearable wireless device.

Bluetooth applications Bluetooth is a technology for short-range ad-hoc data links. Bluetooth

employs radio frequencies in the 2,4-2,5 GHz band – so called industrial, scientific, and medical (ISM) band, which is open for public use. Bluetooth-enabled devices (PDA’s, cell phones, computers, peripherals..) will be able to communicate directly with each other over short distances, or through Bluetooth-enabled wired local-area networks, perhaps across a meeting room or a football field or airport. Units that work at to 100 meters apart are possible, but 10 meter or so applications are likely to be most common. Bluetooth does not require a line of sight to work and covers much greater distances.

Figure 6. Sample of Bluetooth universal access point at an airport

The figure 6. we can see the Bluetooth access point application at an airport, where people can access local and wide area network, ad-hoc Bluetooth connections are used to interconnected carried devices, such as PDAs, WCDMA mobile phones and notebook computers. For instance, a user might retrieve e-mail via a HiperLAN/2 interface to a notebook in a briefcase, but read messages and reply to them via his or her PDA.

And the other applications we can see the figure 7. a combination of PAN interconnection and Internet access. A scatternet with three interconnected piconets. Via a GPRS/UMTS cellular phone, one piconet provides IP network access to the other two piconets.

Figure 7. Sample of Bluetooth scatternet

BEYOND THE 3G MOBILE

The IST (Information Society Technologies) program in the most recent strategic initiative of the European Community. An important goal of the IST Program is to define the scope and features of the fourth generation of mobile networks and services. Even though the program recently began operating, it has already identified the key evolution steps from 3G to 4G mobile networks and services:

• integration of different wireless systems via network interworking • radio reconfigurable technologies • Guaranteed quality of service levels as required by future applications • Increased network flexibility via self-organizing ad hoc networking

technologies • Adaptive transmissions rates via air interface, allowing for scalable

wireless connectivity • distributed and flexible management of spectrum resources.

CONCLUSIONS

The future wireless networks should be an open platform supporting multicarrier, multibandwith, and multistandard air interfaces, with content-oriented bandwith-on-demand (BoD) services dominant throughout the whole network.

The principal components of COMINT systems are antennas, receivers and processors. The software radio concept is an emerging technology, thought to build flexible radio systems, multiservice, multistandard, multiband, reconfigurable and reprogrammable by software. The software implementation of the user terminal or intelligent COMINT radio able to dynamically adapt to the radio environment in which it is, time by time, located.

Figure 8. Reconfigurable software radio

The figure 8 we can see the reconfigurable multidimensional radio, compact hardware implementation, where minimum software control is required. There are four key modules in the systems:

• the air interface module • base band processing unit, • digital broadband transceiver, and • smart antenna array.

The software-defined radio /SDR/ or software radio to redefine the role of the military radio, turning it into a multimedia, information superiority device for exchanging voice, text, images and other data on the battlefield. And the other hand the software defined COMINT receivers, the enabling to the access different nations and different services when to communicate each other.

REFERENCES

[1] Akiro MORIDERA, Kazuo MURANO: The Network Paradigm of the 21st. Century and Its Key Technologies. IEEE Communications Magazine November 2000. [2] Anders ROCKSTRÖM: Technology as a Driver for New Business Logic, IEEE Communications Magazine November 2000. [3] BALOG Károly: 21st Century Comint Possibilities in The Mirror of 3rd Generation Mobile Systems. Korszerű katonai technológiák a XXI. században című nemzetközi konferencia előadás 2000. 05. 16. [4] Willie W. LU: Compact Multidimensional Broadband Wireless: The Convergence of Wireless Mobile and Access, IEEE Communications Magazine November 2000. [5] Kathleen KOCKS: Cellular Intercept Not Getting Any Easier. Journal of Electronic Defense, 2000. august [6] Magnus FRODIG, Per JOHANSSON, Peter LARSSON: Wireless ad hoc networking – The art of networking without a network. Ericsson Rewiew No. 4, 2000 p248-263 [7] Bechet SARIKAYA: Packet Mode in Wireless Networks:Overview of Transition to Third Generation. IEEE Communications Magazine September 2000. [8] Enrico BURACCHINI: The Software Radio Concept. IEEE Communications Magazine September 2000. [9] Michael PUTTRÉ: A Band For All Reasons (Software radios promise to radically redefine battlefield communications). Journal of Electronic Defense 2001. january vol. 24, no. 1.