The Magic WAND project (wireless ATM network demonstrator) is a project within the European Union ACTS (Advanced Communications Technologies and Services) initiative. The project aims to design, verify, implement and demonstrate a wireless access network for ATM LANs. The WAND system is designed to operate in the 5.2 GHz band for indoor environments with user mobility limited to walking speed. This paper addressed the design and implementation of the wireless transmitter and receiver units and discusses complexity and performance.

The influence of code synchronization errors on the performance of direct-sequence spread-spectrum (DS/SS) communication systems is investigated. Insight is gained in the degradation of some basic performance parameters due to the tracking bias of a noncoherent delay lock loop (DLL). The performance parameters investigated are the bit-error probability, throughput and delay. Numerical results show that for receivers with an early-late spacing of d=1, using a noncoherent DLL, the results of a system performance analysis in a fast fading environment can be much too optimistic if the tracking errors are ignored.

The throughput and delay characteristics of a land-mobile satellite channel are analyzed for both slotted ALOHA. And slotted direct-sequence CDMA (code division multiple access), using binary phase shift keying (BPSK) modulation and forward error correction coding (FEC). In the case of CDMA, the application of path diversity techniques-maximal ratio combining and selection diversity-is also taken into account. Packet success probabilities are derived for both slow and fast fading, in order to evaluate the throughput and delay. Numerical results are presented for arbitrary code lengths and for specific values of the number of resolvable paths. It is shown that CDMA can offer a substantial improvement over slotted ALOHA, especially when the chip time is less than the delay spread.>

The performance of combined FEC/ARQ techniques for a direct-sequence CDMA system using coherent binary phase shift keying (BPSK) modulation is investigated. Throughput and delay are analyzed for the cases of slow and fast fading, considering the application of maximal ratio combining in light and heavy shadowing environments. By calculating the packet success probability, numerical results are presented for the throughput and delay. FEC with selective-repeat ARQ is implemented using BCH codes of varying lengths.

Two different techniques are introduced that can be used to synchronize a CDMA system for both the uplink and the downlink. The advantage of synchronous CDMA is that multi-user interference can be eliminated for the dominant path signals by employing orthogonal codes. The main difficulty of synchronous CDMA is the synchronization of the uplink. This paper discusses how this synchronization can be achieved. It is shown that conventional tracking loops have great problems in achieving the desired synchronization accuracy due to multipath tracking errors. A new tracking system, which estimates both line-of-sight and multipath parameters, is shown to give much better results.

The performance of a direct-sequence spread-spectrum land-mobile satellite transmission system, using binary phase-shift keying (BPSK) modulation, is analysed. The satellite channel is modeled as having Rician fading characteristics. The bit-error probability is evaluated, considering both the envelope and the phase variation. Assuming a Gaussian approximation for the interference, numerical results are obtained for both spread-spectrum and narrowband land-mobile satellite communication systems with BPSK modulation. A comparison of the two systems is made for light, average, and heavy shadowing.>