WIRELESS COMMUNICATION TECHNOLOGIES

Wireless Communication Technologies

Wireless Communication Technologies

Introduction

As wireless technology emerges into the mainstream of the networking and communications markets, the wireless development community has a unique opportunity to be proactive, rather than reactive, in its approach to security. At this early point in the wireless industry, developers can anticipate future security needs and integrate security considerations into every stage of the development process. Wireless Security and Privacy shows developers how to take advantage of this exceptional opportunity (Karygiannis and Owens 2002). The term wireless means different things to different people. In general, the term reflects any means of communication that occurs without wires.

IEEE 802.11

In order for WLANs to be widely accepted, there needed to be an industry standard devised to ensure the compatibility and reliability among all manufacturers of the devices. The Institute of Electrical and Electronics Engineers (IEEE) has provided just that. The original standard IEEE 802.11 was defined as a standard in 1997 followed by IEEE 802.11a and IEEE 802.11b in September of 1999.

“The 802.11b specification was ratified by the IEEE in July 1999 and operates at radio frequencies in the 2.4 to 2.497 GHz bandwidth of the radio spectrum” (Yuan 2002 312). The modulation method selected for 802.11b is known as complementary direct sequence spread spectrum (DSSS) using complementary code keying (CCK) making data speeds as high as 11 Mbps.

A multi-channel architecture was proposed in that uses a distributed channel assignment algorithm and considers non-overlapping channels as part of independent interference domains. The same assumption is considered by Tickoo Sikdar (2004) who mathematically formulates a joint channel assignment and routing problem.

In contrast with these works we claim that the assumption of perfect independence between non-overlapping operating channels does not always hold in practice. In this paper, which extends the preliminary results reported in , we demonstrate the presence of detrimental interference effects also between “non-overlapping” channels by means of specific experiments with commercially available hardware. The central problem is that cross-channel interference is neither tackled by the standards nor handled adequately by the MAC layer (Karygiannis and Owens 2002). As a consequence its deleterious effects can be more severe than intra-channel interference between different transmitters. This is particularly critical in multi-hop topologies, where relay nodes act as transmitter and receiver simultaneously. Our findings call for a revision of some past research results in the area of multi-channel multi-hop networks based on IEEE 802.11.

Wired equivalent Privacy

WEP is a protocol that adds security to wireless local area networks (WLANs) based on the 802.11 Wi-Fi standards. WEP is an OSI Data Link layer (Layer 2) security technology that can be turned "on" or "off." WEP was designed to give wireless networks the equivalent level of privacy protection as a comparable wired network. WEP is based on a security scheme called RC4 that utilizes a combination of secret user keys and system-generated values (Yuan 2002). The original implementations of WEP supported so-called 40-bit encryption, having a key of length 40 bits and 24 additional bits of system-generated data (64 bits ...