Sample Figure: GSM Network architecture
The multi-media presentation contains a discription of many wireless communication systems, such as GSM, DECT, AMPS, Cellular CDMA, Wireless LANs and DAB. The principal technical parameters are discussed, together with a summary of the history, background and potential of each system.
Still, there remain technical bottlenecks in the development of a ubiquitous wireless multimedia access, such as the capacity of the radio link, its unreliability due to the adverse multipath propagation channel and severe interference from other transmissions.
Sample Figure: Fading signal amplitude
We cover the principles and fundamental concepts engineers need to tackle these limitations. Channel impairments such as fading and multipath dispersion are addressed with attention to their effect on link and network performance. We progress through the physical aspects of radio propagation to the multiuser issues of radio data networks, combining among other things:
Sample Figure: Frequency reuse distance for C = 7 (i=2, j =1).
You study methods to compute the coverage and outage probability in micro and macro cellular telephone networks and new computational techniques useful for planning cellular networks from topographical databases. We cover capacity enhancements by cell sectorization, reuse partitioning and dynamic channel allocation and statistical voice multiplexing (as used in PRMA). Relevant performance criteria, such as subjective voice quality (signal outages and speech clipping), call blocking probability and lost call rates are applied to cellular networks.
Many new developments in wireless office networks and wireless multimedia services involve spread-spectrum transmission, coexisting with other services or in deregulated (ISM) radio bands. We cover spreading methods such as slow and fast frequency hopping and direct sequence CDMA, and addresses some new developments, such as orthogonal frequency division multiplexing (OFDM)and multicarrier CDMA. Their performance is discussed in relation to wideband channel models. The concept of the RAKE receiver is presented.
As we look to future wireless computer, multimedia networks or communication networks for Intelligent Transport Systems, the multiple access issue becomes substantially more important than it is for circuit-switched voice communication. The ALOHA, CSMA and ISMA protocols all allow multiple users to share radio communication resources. How these protocols perform differs substantially for guided (wired) and unguided (radio) channels; performance is highly dependent on the physical characteristics of the channel.
To attempt a realistic analysis of the performance of wireless radio networks, the assumptions that a data packet is always received successfully if no conflicting transmission (collision) occurs simultaneously on the same channel and that data packets involved in a collision are always lost, must be refined. Moreover, the performance seen by each participating terminal differs from the network average performance and is highly dependent on the terminal's location. Throughout, stability and delay are discussed in relation to channel characteristics, collisions with other transmissions within the same cell, and random interference from other cells. Specific solutions exist to efficiently resolve message collisions: these include the tree algorithm, the stack algorithm and dynamic frame length ALOHA.
You study recent developments for efficient frequency reuse in wide-area wireless data networks. In particular, you learn how frequency reuse and multiple access schemes suitable for future packet-switched networks differ from existing cellular systems for telephony and from multiple access schemes used on wireline local area networks.
To access the material on the CD-ROM, you need a
World Wide Web browser. However, an on-line Internet
connection is not necessary. Because CD-ROM contains files that can be read by
browsers such as Hypertext Mark-Up Language
ps, etc, the
CD-ROM works independently of the platform you
use. In particular, you can use PC Windows, DOS, Mactintosh or Unix browsers.