For the problems of the unfeasibility of the optical fiber deployment and the inflexibility of the network optimization in the current Distributed Antenna System (DAS) based on Radio over Fiber (RoF) technology, this paper presents a novel wireless network architecture using Radio over Free Space Optics (RoFSO) for wireless local area networks (WLANs). RoFSO not only transmits various kinds of radio services on optical wireless carrier, but also overcomes the defect of the unfeasibility of the optical fiber deployment. In addition, a RF assignment mechanism based on the wireless network architecture presented is proposed and studied, which can achieve efficient utilization of RF resources. The results of simulation show that the improvement in throughput performance can be obtained when the number of wireless users is increased and RF resources are fairly used in terms of fairness index.

Satisfying critical QoS requirements in next generation networks poses major challenges, due to its intrinsic complexity of network resource allocation. This paper considers the problem of load balance based bandwidth allocation for delay sensitive services. For satisfying deterministic end-to-end delay requirement, a simple and efficient algorithm for path level optimal bandwidth allocation, path level equal ratio allocation algorithm (P-ERA), is developed first. Based on P-ERA, another algorithm for network level optimized bandwidth allocation, network level equal ratio allocation algorithm (N-ERA), is also presented for much more complicated network circumstances. N-ERA algorithm features appropriate route selection and balanced bandwidth allocation, and can adaptively avoid, or at least delay, the emergence of network bottleneck when a network is heavily loaded. Extensive simulations indicate that N-ERA algorithm can make full use of network bandwidth and admit more services, even if they are delay critical, than other ones dealing with the same problem. And the less computation complexity of N-ERA algorithm makes it of great application value.

To make the exiting fault routing algorithms tolerate concave fault regions without disabling any healthy nodes, the concept of hole is proposed in this paper. A hole consists of healthy nodes in the concave parts and neighborhood of a given concave fault region. By guiding the packet routing inside and outside the hole, the new routing method empowers the convex fault tolerant routing algorithm to tolerate concave shape regions without disabling any healthy nodes. The proposed modification method is simple and does not add new virtual channels. Moreover, it doesn’t change the rules of the previous algorithms. Finally, the performance of the modified routing algorithm is simulated under various concave fault patterns.

This paper proposes a dynamic routing optimal model in IP/MPLS over WDM networks. A corresponding on-line integrated routing algorithm minimizing the cost of total lightpaths (MCTLP) is designed accordingly. MCTLP optimizes the network resource utilization by integrally assigning bandwidth allocations on both IP layer and wavelength links usage on WDM layer. The performance comparison of MCTLP with two representative routing algorithms used in IP/MPLS over WDM networks via simulation shows that MCTLP can use less links on IP layer and WDM layer to carry IP traffic flows, resulting in accepting more connection requests and reducing the traffic blocking probability efficiently.

Cyclic Cubes, proposed as a new family of interconnection networks, is proved not new and is equivalent to the wrapped butterfly networks. There is a similar fact that the Cyclic Cubes is also equivalent to the Bidi Shufflenet, which is investigated recently. But this fact is almost neglected. In this paper, we discuss the equivalence between the Cyclic Cubes and the Bidi Shufflenet.

We propose a deadlock-free wormhole routing scheme called Zigzag routing for the pan-Mesh, which generalizes the mesh topology. Accordingly, we prove that only two virtual channels are needed for deadlock-freeness on every physical channel by using Zigzag routing.

In OFDM (Orthogonal Frequency Division Multiplexing) system, if the length of its cyclic prefix is larger than the delay spread of channel, we can get a simple frequency equalizer to demodulate OFDM signal. However, the use of cyclic prefix degrades the efficiency of transmission greatly. So, we give a new equalizing structure, which improve the efficiency of transmission of OFDM system.

IEEE is currently standardizing a new high-speed backbone technology for MANs - the Resilient Packet Ring (RPR). A key performance objective of RPR is to achieve high utilization, spatial reuse, and fairness simultaneously. However, the algorithms proposed in current draft standards have some critical limitations. As shown in an unbalanced traffic scenario, the draft RPR algorithm will suffer from dramatic bandwidth oscillations within nearly the entire range of the link capacity. In this paper, we propose a new dynamic bandwidth allocation algorithm called Distributed Bandwidth Reallocated in Rings (DBRR), which is based on approximately virtual-time. It shows that with fairness information propagated along the ring, each node can remotely approximate the ideal fair rate for its own traffic at each downstream link, and the whole ring can obtain maximum spatial reuse and nearly lossless throughput.

It is essential for the development of bandwidth allocation schemes to study the resource management and traffic control in ATM networks. It is important to accurately evaluate the efficiency of various bandwidth allocation schemes. However, in the multimedia environment of ATM networks, it has been recognized that the performance analyses are very complicated because the source modeling is the non-Poisson arrival process. In this paper we propose a measurement-estimation based approach to analyzing the polling systems with server time-outs, and with Markov modulated Poisson arrival process (MMPP). These models can be used to estimate the efficiency of the DTS-like bandwidth allocation schemes. The idea is to transform the aggregated source stream into Poisson flow with constant rate during the fixed time interval. The method is to count cells in consecutive fixed intervals. The aggregated source state is estimated from the measured number of cells during the fixed interval. If the state is estimated to be j, the arrival process is assumed to be a Poisson process with rate j/spl lambda/ during the fixed interval. Therefore, the analytical results of the time-limited polling models with conventional simple source modeling can be used to evaluate efficiency of the bandwidth allocation scheme in ATM networks.

The time-limited cyclic service model can be used to evaluate the performance of bandwidth allocation scheme in ATM/B-ISDN networks. This model does not lend itself to an exact solution. We propose an approach to analyzing it, in which the time limitation is an exponential distribution. Firstly, we derive a functional equation that characterizes the amount of work when the server visits a queue. The expression for mean customer waiting time is then obtained. In addition, we suggest a method to optimally select the value of time limitations, by which server (or bandwidth) utilization can be increased.