The use of radio communication in indoor environment such as offices, fac-tories, hospitals, museums, convention centers etc, is very convenient and some-times necessary. The fast growing in circuits technology and the availability of unlicensed frequency bands allow many possibilities for commercial wireless products. The challenge for system designers is to build a system that can sup-port multiple users and is robust to interference from other systems within the same unlicensed band....[ Read more ]

The use of radio communication in indoor environment such as offices, fac-tories, hospitals, museums, convention centers etc, is very convenient and some-times necessary. The fast growing in circuits technology and the availability of unlicensed frequency bands allow many possibilities for commercial wireless products. The challenge for system designers is to build a system that can sup-port multiple users and is robust to interference from other systems within the same unlicensed band.

The aim of the thesis is to design a multiple-user system in the 2.4GHz ISM band. The system should support applications that require low delay and high data rate. In particular, the system should be able to support real time voice communication and at the same time, provides a high speed physical layer for wireless LANs.

The characteristics of the indoor channel at 2.4GHz were carefully studied. Practical constraints were translated to constraints in the system parameters. After comparing several possible system designs, we proposed a slow frequency hopped system employing Reed-Solomon code with erasure decoding. Simula-tion tools were developed and were used to fine tune the system parameters.

While designing and analyzing the system, we observed the capture phe-nomenon of a frequency hopped system in fading environment. The capture phenomenon significantly affects the system performance and we studied this effect in detail.

Impact of using multiple antennas to provide antenna diversity was also stud-ied and we found that significant improvement in performance can be achieved.

The possibility of using concatenated codes was explored and concatenated coding scheme was shown to be useful only for applications that need low packet error rate, provided that large delay is allowed.

We proposed the use of unique test pattern for each user to generate side information and to increase the probability of capture. Using BPSK with co-herent detection, Reed-Solomon( 127, 91) code with erasure decoding and two antennas, the proposed system can support more than 20 asynchronous users each having a data rate of 700kbps.