We focus on delivering radio engineers a practical design of macro-micro code division multiple access (CDMA) cellular overlays. First, we review our algorithmic approach to jointly deploy macrocells and microcells over today's big urban areas having spatially nonuniform traffic distributions. Next, we identify several further issues related to the optimal design of macro-micro cellular overlays and enhance the cell-deploying algorithm to reflect these issues. The numerical results by extensive event-driven simulations show that the resulting macro-micro cellular overlays successfully cope with the existing conditions of today's big urban areas, such as spatial and temporal traffic distributions and user mobility characteristics. Finally, we discuss the practical guidelines for designing macro-micro cellular overlays in the existing big urban areas.

We study fault-tolerant multicasting in multistage interconnection networks (MINs) for constructing large-scale multicomputers. In addition to point-to-point routing among processor nodes, efficient multicasting is critical to the performance of multicomputers. This paper presents a new approach to provide fault-tolerant multicasting, which employs the restricted header encoding schemes. The proposed approach is based on a recursive scheme in order to send a multicast packet to the desired destinations detouring faulty element(s). In the proposed fault-tolerant multicasting, a multicast packet is routed to its own destinations in only two passes through the MIN having a number of faulty elements by exploiting its nonblocking property.

We discuss the multicast communication in the self-routing multistage interconnection network (MIN) for constructing the internal architecture of asynchronous transfer mode (ATM) switches. Many applications of ATM switches require multicast communications in addition to conventional point-to-point communications. This paper presents a novel approach to supporting multicast communication, on the basis of the recursive scheme that recycles a multicast packet one or more times through the network to reach at desired destinations. We also propose cost-effective multicast algorithms providing deadlock-freedom in MIN-based ATM switches. The proposed algorithms require a small and fixed number of recycling passes and a reasonable number of links used. The proposed algorithms can be easily applicable to buffered MIN-based ATM switches.

An ATM switch based on multistage interconnection networks with multiple paths can support higher bandwidth than that of buffered networks with single path by passing multiple packets to the same destination simultaneously. These multiple packets are buffered in the output buffer of the destination. The performance of output buffer in the switch with multiple paths is closely dependent on the output traffic distribution, which is the packet arrival rate at each output link destined to a given output port. As the nonuniformity of the output traffic distribution becomes higher, the performance of the output buffer as like delay and packet loss probability gets better. In this paper, we propose a new self-routing switch architecture with multiple paths called Fly network and analyze the performance of the switching network and the output buffer focusing on the output traffic distribution. It is shown that the Fly network supports best throughput and latency of the output buffer by producing a high degree of the nonuniform output traffic distribution.

The authors describe an extended backpropagation algorithm for fully connected recurrent neural networks applied to speech recognition. The extended delta rule is approximated by excluding some of the past activities of the dynamic neurons to reduce computational complexity without performance degradation. In speaker-dependent recognition of a confusable syllable set, the fully recurrent neural network with the approximated backpropagation algorithm showed better performance than the multilayer perceptron and the self-recurrent network with comparable time complexity. In addition, it is found that most self-recurrent connections become excitatory and most mutual recurrent connections become inhibitory.>

Invariant acoustic-phonetic features conveyed simultaneously by the stable and the transient portion of the speech signal are investigated quantitatively using a relational cue. To represent the relational cue effectively, a peak-weighted binary spectrum is proposed. Prevocalic nasal recognition results show speaker independence and improved performance in comparison with dynamic time-warping methods.>

This paper proposes a microdiagnostic procedure for efficient fault diagnosis of bit-slice processors that are formed by an array of identical bit-slice processors. A test generation procedure for testing the entire array simultaneously instead of testing single slice, one after another, is presented, which is based on the high functional fault model and restricted multiple slice fault assumption within an array. Fault detection and fault location procedures using the generated test sequence are also presented.