This paper proposes a medium access control (MAC) protocol for single-hop WDM star-coupler networks, in which the number of stations is larger than the number of channels and the stations have arbitrary distances to the star coupler. The proposed protocol has one control channel for reserving the slots of data channels and several data channels which are used to transmit traffic. This paper also suggests a scheme that accomplishes load balancing among data channels for arbitrary traffic patterns between stations. Since this load balancing scheme diminishes an influence that traffic patterns have on the performance of the proposed MAC protocol, the proposed system is appropriate for systems which have asymmetric traffic intensity between stations. Throughput and mean message delay of the MAC protocol are analyzed using a discrete time Markov process and a D/G/1 queue with batch arrivals. The numerical results show that the performance is improved as the message length increases, the maximum round-trip propagation delay decreases, and the number of data channels increases.

As a means of CDMA network evolution toward future wireless services, a spectral overlay of narrowband CDMA (N-CDMA) and wideband CDMA (W-CDMA) systems is proposed in [8]. In order to justify the overlaying strategy, the reverse link capacity is examined in the same work. Although the capacity of conventional CDMA cellular systems is usually limited by the reverse link, the limit could occur at the forward link depending on the transmission technologies adopted by specific CDMA proposals. Especially, the number of users that can be simultaneously accommodated in the system would be limited by the forward link in future mobile service environments where unequal traffic is offered between two links. In this paper, we first examine the forward link capacity of the spectrally overlaid narrowband and wideband CDMA (N/W CDMA) system. And we compare it with the reverse link capacity to obtain the overall performance. The effects of various parameters on the capacity of N/W CDMA system are numerically evaluated for different mobile environments.

The soft handoff is widely adopted in code division multiple access (CDMA) systems for its many advantages mainly resulting from site diversity. However, in the forward link, other cell interference can be increased by soft handoff, decreasing system capacity. In future mobile systems, provision for the sufficient forward link capacity is very important since the forward link load is much higher than the reverse link load in mobile multimedia services such as Internet access. In this paper, we consider a combined handoff strategy in which voice services are provided with soft handoff whereas data services are supported with hard handoff. We analyze the effect of handoff method on the forward link performance. The performance measures we use are the outage probability of the bit energy to noise density ratio and the capacity based on the outage probability. As a result, we show that the combined handoff is very useful in CDMA cellular networks supporting both voice and data services simultaneously.

This paper proposes local lightwave networks with grouping property which are based on a wavelength division multiplexing (WDM). The proposed network is partitioned into several groups according to traffic volume between stations so that traffic is more likely to be within groups. The stations within a group are connected to a broadcast-and-select WDM network with star topology. For inter-group communication, a WDM network of each group is connected to another star-topology WDM network through a special station called a router. In the proposed network, intra-group communication is achieved by one hop and inter-group communication goes through multiple hops. We analyze the average hop number, the maximum throughput, and the mean packet delay of the proposed network and investigate its performance characteristics. Since the proposed network has the better performance as its grouping property strengthens, it is fit for local lightwave networks with the locality of traffic.