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We address the symbol-level precoding design problem for the downlink of a multiuser millimeter wave (mmWave) multiple-input multiple-output (MIMO) wireless system where the transmitter is equipped with a large-scale antenna array. The high cost and power consumption associated with the massive use of radio frequency (RF) chains prohibit fully-digital implementation of the precoder, and therefore, we consider a hybrid analog-digital architecture where a small-sized baseband precoder is followed by two successive networks of analog on-off switches and variable phase shifters according to a fully-connected structure. We jointly optimize the digital baseband precoder and the states of the switching network on a symbol-level basis, i.e., by exploiting both the channel state information (CSI) and the instantaneous data symbols, whereas the phase-shifting network is designed only based on the CSI due to practical considerations. Our approach to this joint optimization is to minimize the Euclidean distance between the optimal fully-digital and the hybrid symbol-level precoders. Remarkably, the use of a switching network allows for power-savings in the analog precoder by switching some of the phase shifters off according to the instantaneously optimized states of the switches. Our numerical results indicate that, on average, up to 50 percent of the phase shifters can be switched off. We provide an analysis of energy efficiency by adopting appropriate power dissipation models for the analog precoder, where it is shown that the energy efficiency of precoding can substantially be improved thanks to the phase shifter selection approach, compared to the fully-digital and the state-of-the-art hybrid symbol-level schemes. [ABSTRACT FROM AUTHOR]

Considering a dual-hop energy-harvesting (EH) relaying system, this paper advocates novel relaying protocols based on adaptive time-switching (TS) for amplify-and-forward and decode-and-forward modes, respectively. The optimal TS factor is first studied, which is adaptively adjusted based on the dual-hop channel state information (CSI), accumulated energy, and threshold signal-to-noise ratio (SNR), to achieve the maximum throughput efficiency per block. To reduce the CSI overhead at the EH relay, a low-complexity TS factor design is presented, which only needs single-hop CSI to determine the TS factor. Theoretical results show that, in comparison with the conventional solutions, the proposed optimal/low-complexity TS factor can achieve higher limiting throughput efficiency for sufficiently small threshold SNR. As the threshold SNR approaches infinity, the throughput efficiency of the proposed optimal/low-complexity TS factor tends to zero in a much slower pace than that of the conventional solutions. Simulation results are presented to corroborate the proposed methodology. [ABSTRACT FROM PUBLISHER]

Scheduling algorithms are crucial for most existing switches to improve the throughput. However, the delay of the switching fabric cannot be guaranteed with such scheduling algorithms. This paper aims to design a novel load-balanced wire-speed multicast switching fabric along with the attractive merits of network coding. We adopt a two-phase self-routing switching fabric constructed by Boolean-multicast concentrators (SRBMCs), where the first SRBMC distributes the incoming cells to its outputs uniformly and the second allows the distributed cells to be self-routed and multicast to their destinations concurrently. To further improve the switching performance, linear network coding is smoothly combined with SRBMC to reduce the packet loss rate. Theoretical analysis and numerical simulation demonstrate that the proposed switching fabric cannot only achieve wire-speed multicast switching but also be recursively constructed into an indefinite large-scale one with such merits as no internal buffers, low complexity, and guarantee in switching delay. Finally, we implement the proposed fabric on Field-Programmable Gate Array and verify its performance in multicast switching. [ABSTRACT FROM AUTHOR]

With finite-rate feedback, we propose two feedback methods for transmit beamforming in a point-to-point MISO-OFDM channel. For the first method, a receiver with perfect channel information, quantizes and feeds back the optimal transmit beamforming vectors of a few selected subcarriers, which are equally spaced. Based on those quantized vectors, the transmitter applies either constant, linear, or higher-order interpolation with the remaining beamforming vectors. With constant interpolation, we derive the approximate sum achievable rate and the optimal cluster size that maximizes the approximate rate. For linear interpolation, we derive a closed-form expression for the phase rotation by utilizing the correlation between OFDM subcarriers. We also propose a higher-order interpolation that requires more than two quantized vectors to interpolate transmit beamformers, and is based on existing channel estimation methods. Numerical results show that interpolation with the optimized cluster size can perform significantly better than that with an arbitrary cluster size. For the second proposed method, a channel impulse response is quantized with a uniform scalar quantizer. With channel quantization, we also derive the approximate sum achievable rate. We show that switching between the two methods for different feedback-rate requirements can perform better than the existing schemes. [ABSTRACT FROM AUTHOR]

Design of high bandwidth and reliable feeder links are central toward provisioning new services on the user link of a multibeam satellite communication system. Toward this, utilization of the Q/V band and an exploitation of multiple gateways (GWs) as a transmit diversity measure for overcoming severe propagation effects are being considered. In this context, this contribution deals with the design of a feeder link comprising $N+P$ GWs ( $N$ active and $P$ redundant GWs). Toward provisioning the desired availability, a novel switching scheme is analyzed and practical aspects such as prediction-based switching and switching rate are discussed. Unlike most relevant works, a dynamic rain attenuation model is used to analytically derive average outage probability in the fundamental $1+1$ GW case. Building on this result, an analysis for the $N+P$ scenario leading to a quantification of the end-to-end performance is provided. This analysis aids system sizing by illustrating the interplay between the number of active and redundant GWs on the chosen metrics: average outage and average switching rate. [ABSTRACT FROM PUBLISHER]

This paper defines a procedure for designing the architecture of multistage switching networks. Our proposal is the result of a systematic study of the properties of multistage networks on one side and of optical switching systems on the other side. Modularity of the implementation is the primary concern, allowing the construction of a generic-size fabric by the simple cascading of multiple-stage modules. In this paper, we show in detail the application of the approach to a family of banyan networks, although the method can be extended to other types of networks. The designed architecture can be exploited for various implementation technologies, for instance, integrated optics and free-space optics. The method can even be applied to electronic VLSI/ULSI circuits. After presenting the design procedure, we discuss practical implementations in different technology scenarios. The main contribution of this paper is to simplify the building of large switches by cascading a number of switching modules that combine the internal stage architecture with the interconnection between stages. [ABSTRACT FROM AUTHOR]

The article lists the editors of the IEEE Communications Society including Robert Schober; Mendi Bennis; and Octavia Dobre.

A Guaranteed-Rate scheduling algorithm for packet-switched IP routers with rate, delay and jitter guarantees is proposed. The algorithm can be used to schedule traffic with 100% throughput in Input-Queued IP routers with unity speedup. The traffic is scheduled according to transmission frames of duration F time-slots. An NxN doubly stochastic traffic rate matrix specifies a traffic rate between each pair of IO ports. The matrix is quantized and recursively decomposed into a sequence of F permutations. Each permutation is used to configure the crossbar switch for one time-slot without requiring additional scheduling. The recursive fair stochastic matrix decomposition is based upon the routing of a permutation through a binary rearrangeable network. In the resulting transmission schedule, the expected Inter-Departure Time (IDT) of a cell equals the Ideal IDT (IIDT), and the maximum IDT and service lag of a cell are bounded by an integer number of IIDTs. The delay and delay jitter experienced along an end-to-end path in a packet-switched IPIMPLS network are therefore small and bounded by an integer number of IIDTs, and the buffer sizes within the IP routers are small and bounded. The proposed algorithm can be used to schedule Guaranteed-Rate traffic in packet-switched IPIMPLS networks, to provide near-optimal queueing delays and essentially-zero delay jitter along end-to end paths when playback buffers are employed. [ABSTRACT FROM AUTHOR]

A performance optimization based on the optimal switching threshold(s) for a multi-branch switched diversity system is discussed in this paper. For the conventional multi-branch switched diversity system with a single switching threshold, the optimal switching threshold is a function of both the average channel SNR and the number of diversity branches, where computing the optimal switching threshold is not a simple task when the number of diversity branches is high. The newly proposed multi-branch switched diversity system is based on a sequence of switching thresholds, instead of a single switching threshold, where a different diversity branch uses a different switching threshold for signal comparison. Thanks to the fact that each switching threshold in the sequence can be optimized only based on the number of the remaining diversity branches, the proposed system makes it easy to find these switching thresholds. Furthermore, some selected numerical and simulation results show that the proposed switched diversity system with the sequence of optimal switching thresholds outperforms the conventional system with the single optimal switching threshold. [ABSTRACT FROM AUTHOR]

Diversity techniques play a key role in modern wireless systems, whose design benefits from a clear understanding of how these techniques affect system performance. To this aim we propose a simple class of bounds, whose parameters are optimized, on the symbol error probability (SEP) for detection of arbitrary two-dimensional signaling constellations with diversity in the presence of non-ideal channel estimation. Unlike known bounds, the optimized simple bounds are tight for all signal-to-noise ratios (SNRs) of interest. In addition, these bounds are easily invertible, which enables us to obtain bounds on the symbol error outage (SEO) and SNR penalty. As example applications for digital mobile radio, we consider the SEO in log-normal shadowing and the SNR penalty for both maximal ratio diversity, in the case of unequal branch power profile, and subset diversity, in the case of equal branch power profile, with non-ideal channel estimation. The reported lower and upper bounds are extremely tight, that is, within a fraction of a dB from each other. [ABSTRACT FROM AUTHOR]

In optical burst switched (OBS) networks, the queueing delay in ingress edge node is an important performance measure. In this paper, we propose a deterministic delay model and derive the upper bound of the burst queueing delay in an edge node. On this basis, the edge-to-edge delay guarantee framework for premium services is further outlined. [ABSTRACT FROM AUTHOR]

The constructions of optical queues is one of the most critically sought after optical technologies in all-optical packet-switched networks, and constructing optical queues directly via optical Switches and fiber Delay Lines (SDL) has received a lot of attention recently in the literature. A practical and challenging issue in the constructions of optical queues is on the fault tolerant capability of such constructions. In this paper, we focus on the constructions of fault tolerant optical linear compressors and linear decompressors. The basic network element for our constructions is scaled optical memory cell, which is constructed by a 2 × 2 optical crossbar switch and a fiber delay line. We first obtain a fundamental result on the minimum construction complexity of a linear compressor by using fiber delay lines as the storage devices for the packets queued in the linear compressor. This result shows that one of our previous constructions of a linear compressor by a concatenation of scaled optical memory cells is an optimal construction in the sense of minimizing the construction complexity. However, such an optimal construction lacks the fault tolerant capability. To construct a linear compressor with fault tolerant capability, we give a multistage construction of a self-routing linear compressor by a concatenation of scaled optical memory cells, and show that if the delays, say d1, d2…, dM of the fibers in the scaled optical memory cells satisfy a certain condition (specifically, the condition in (A2) given in Section IV-A), then our multistage construction can be operated as a self-routing linear compressor with maximum delay ΣM-Fi=1 di in the worst case even after up to F of the M scaled optical memory cells fail to function properly, where 0 < F < M - 1. Furthermore, we prove that our multistage construction with the fiber delays d1, d2,…, dM given by the generalized Fibonacci sequence of order F is the best among all of the constructions of a linear compressor that can tolerate up to F faulty scaled optical memory cells by using M scaled optical memory cells. Similar results are also obtained for the constructions of fault tolerant linear decompressors. [ABSTRACT FROM AUTHOR]

We consider Label Switched Path (LSP) protection for connections with various protection grade requirements in multi-protocol label switching (MPLS) over wavelength division multiplexing (WDM) optical networks. In full protection, bandwidth needs to be reserved for the backup LSP to protect the failure of any fiber along the primary LSP. In this paper, we study the problem of partial spatial-protection (PSP) where bandwidth is reserved for the backup LSP to protect the failure of a subset of fibers traversed by the primary LSP to satisfy the specified protection grade. We formulate the optimal LSP PSP problem as an ILP and identify three suboptimal problems. For each suboptimal problem, an exhaustive search algorithm and a heuristic are developed. We analyze the probability that a connection can be restored upon a fiber failure and find that it is higher than or equal to the protection grade specified. We also develop a failure recovery protocol which specifies recovery operations upon failure and determines whether a connection can be recovered if the failed fiber is one of its unprotected fibers. Through extensive simulation experiments, we demonstrated that the proposed LSP PSP algorithms perform better than shared LSP protection in blocking probability and resource efficiency. [ABSTRACT FROM AUTHOR]

The article presents a list of members of Institute of Electrical and Electronics Engineers (IEEE) Communications Society, which include Julian Cheng; ‪Deniz Gunduz; and ‪Chau Yuen‬.

Optical burst switching (OBS) is a promising technique for wavelength division multiplexing (WDM) networks. In practice, wavelength converters (WCs) are either absent or only sparsely deployed in WDM networks due to economic and technical limitations. Thus, wavelength assignment is expected to be an important component of OBS networks. In this paper, an offline wavelength assignment scheme in OBS networks without wavelength conversion capability is proposed. The key idea of the scheme is to decide the wavelength searching order of each traffic connection at edge nodes according to the wavelength priorities determined by the calculated burst loss probabilities on different wavelengths. Simulation results indicate that the proposed scheme can reduce the network-wide burst loss probability significantly compared with other schemes. It is also illustrated that the performance of the proposed scheme can be further enhanced by a larger number of wavelengths per link and a reasonable delay bound at edge nodes. [ABSTRACT FROM AUTHOR]

The switching rates of dual selection combining diversity and dual switch-and-stay combining diversity in Rayleigh, Rician and Nakagami-m (n-i half-integer or integer) fading are derived. Closed-form or single integral expressions are obtained for both the cases of balanced channels and unbalanced channels. [ABSTRACT FROM AUTHOR]

Abstract-Most network operators have considered reducing Label Switched Routers (LSR) label spaces (i.e. the number of labels that can be used) as a means of simplifying management of underlaying Virtual Private Networks (VPNs) and, hence, reducing operational expenditure (OPEX). This letter discusses the problem of reducing the label spaces in MultiProtocol Label Switched (MPLS) networks using label merging - better known as MultiPoint-to-Point (MP2P) connections. Because of its origins in IP, MP2P connections have been considered to have tree-shapes with Label Switched Paths (LSP) as branches. Due to this fact, previous works by many authors affirm that the problem of minimizing the label space using MP2P in MPLS - the MERGING PROBLEM - cannot be solved optimally with a polynomial algorithm (NP-complete), since it involves a hard- decision problem. However, in this letter, the MERGING PROBLEM is analyzed, from the perspective of MPLS, and it is deduced that tree-shapes in MP2P connections are irrelevant. By overriding this tree-shape consideration, it is possible to perform label merging in polynomial time. Based on how MPLS signaling works, this letter proposes an algorithm to compute the minimum number of labels using label merging: the Full Label Merging algorithm. As conclusion, we reclassify the MERGING PROBLEM as Polynomial-solvable, instead of NP-complete. In addition, simulation experiments confirm that without the tree-branch selection problem, more labels can be reduced. [ABSTRACT FROM AUTHOR]

Traditionally, conflict resolution in an input- buffered switch is solved by finding a matching between inputs and outputs per time slot, which incurs unscalable computation and communication overheads. The main objective of this paper is to propose a scalable solution, called the mailbox switch, that solves the out-of-sequence problem in the two-stage switch architecture. The key idea of the mailbox switch is to use a set of symmetric connection patterns to create a feedback path for packet departure times. With the information of packet departure times, the mailbox switch can schedule packets so that they depart in the order of their arrivals. Despite the simplicity of the mailbox switch, we show via both the theoretical models and simulations that the throughput of the mailbox switch can be as high as 75%. With limited resequencing delay, a modified version of the mailbox switch achieves 95% throughput. We also propose a recursive way to construct the switch fabrics for the set of symmetric connection patterns. If the number of inputs, N, is a power of 2, we show that the switch fabric for the mailbox switch can be built with N/2 log2 N 2× 2 switches. [ABSTRACT FROM AUTHOR]

Input-queued cell switches employing the oldest- cell-first (OCF) policy have been shown to yield low mean delay characteristics. Moreover, it has been proven that OCF is stable for admissible traffic conditions when executed with a scheduling speedup of 2. However, as link speeds increase, the computational complexity of these algorithms limits their applicability in high port-density switches and routers. To address the scalability issue, we describe a Frame-Based Maximal Weight Matching (FMWM) algorithm, employing OCF as queue weights, in which a new scheduling decision is issued once every several cell times. Between scheduling decisions, the configuration of the crossbar switch remains unchanged. We further extend the analysis to address the case of multiple classes of service, and prove that the algorithm is stable with an internal buffer transfer speedup of 2, thereby significantly relaxing the timing constraints imposed on the scheduling process. [ABSTRACT FROM AUTHOR]

This paper considers a general parallel buffered packet switch (PBPS) architecture which is based on multiple packet switches operating independently and in parallel. A load-balancing mechanism is used at each input to distribute the traffic to the parallel switches. The buffer structure of each of the parallel packet switches is based on either a dedicated, a shared, or a buffered-crosspoint output-queued architecture. As in such PBPS multipath switches, packets may get out of order when they travel independently in parallel through these switches, a resequencing mechanism is necessary at the output side. This paper addresses the issue of evaluating the minimum resequence-queue size required for a deadlock-free lossless operation. An analytical method is presented for the exact evaluation of the worst-case resequencing delay and the worst-case resequence-queue size. The results obtained reveal their relation, and demonstrate the impact of the various system parameters on resequencing. [ABSTRACT FROM AUTHOR]

Examples of low-complexity diversity combining schemes are, among others, the generalized selection combining (GSC) scheme and the generalized switch-and-examine combining (GSEC). In this paper, we propose a new low-complexity combining scheme, termed generalized sort-switch-and-examine combining (GSSEC), that, in a sense, can be considered as a hybrid GSCIGSEC scheme. A generic expression for the moment-generating function of the GSSEC output SNR in general independent, identically distributed fading channels is derived, and is then applied to the analysis of its error performance. [ABSTRACT FROM AUTHOR]

In this letter, we propose a three-dimensional Markov chain model for the 802.lle enhanced distributed channel access (EDCA) mode. This model can be used to compute the maximum sustainable throughput and service delay distribution for each priority class when under saturation load. The new framework models the performance impact of major quality-of-service (Q0S)- specific features (e.g., CWMin, CWMax, AIFS, internal collision resolution) of the 802.11e EDCA mode, and hence can provide an analytical approach to pick the parameter values associated with EDCA to meet the QoS requirements of each priority. [ABSTRACT FROM AUTHOR]

Many components used in communication systems are nonlinear and have a peak power or peak amplitude constraint. Nonlinearity generates distortions and thus signal-to-noise- and-distortion ratio (SNDR) is an appropriate performance measure. In this paper, we are interested in finding the nonlinear mapping that maximizes the SNDR subject to the peak amplitude constraint. The answer is a soft limiter with gain calculated based on the noise power and the probability density function of the input amplitude. We also investigate a bounding relationship between the SNDR and capacity of the nonlinear channel. The results of this paper can be applied for efficient transmission of high peak-to-average power ratio signals or for optimal linearization of nonlinear devices. [ABSTRACT FROM AUTHOR]

Input-buffered switches have been widely considered for implementing feasible packet switches. However, their matching process may not be time-efficient for switches with high-speed ports. Buffered crossbars (BXs) are an alternative to relax timing for packet switches with high-speed ports and to provide high-performance switching. BX switches were originally considered expensive, as the memory amount required in the cross- points (XPs) is proportional to the square of the number of ports (O(N²)). This limitation is now less stringent with the advances on chip-fabrication techniques, and when considering small crosspoint (XP) buffer sizes. In this paper, we study a combined input- crosspoint buffered packet switch, named CIXB, with virtual output queues (VOQs) at the inputs, and arbitration based on round-robin selection. We show that the CIXB switch achieves 100% throughput under uniform traffic, and high performance under nonuniform traffic, using one-cell XP buffer size and no speedup. [ABSTRACT FROM AUTHOR]

Optical-switching technologies exhibit many characteristics that the electronic-switching technologies do not have. One such characteristic lies in switching states. An electronic crosspoint, having open and close as its two switching states, only allows one traversing signal. But an optical-switching crosspoint, such as a directional coupler or a microelectromechanical systems mirror, usually allows two traversing signals. This paper studies how to exploit the characteristic to expand the switching capabilities of an optical switch, and shows new ways of building more crosspoint-efficient rearrangeable nonblocking switches. We show that an optical 2n × 2n rearrangeable nonblocking switch can be created by cascading only two n × n optical crossbars. [ABSTRACT FROM AUTHOR]

In this paper, we present for the first lime an analytical model that quantifies the mechanism by which offset size affects priority in multiclass optical-burst switching (OBS) systems. Using the model, we derive an exact expression for the distribution of the number of bursts that contend with an arriving burst. The model is applicable to systems in which each class has an arbitrary burst-length distribution and an arbitrary offset size. We also derive accurate approximate expressions for the burst-blocking probability of premium-class traffic, as well as expressions for the sensitivity of premium-class performance to offset jitter and varia- lions in the arrival rates of each class. In a case study, we find that scaling up a system in terms of the number of wavelengths and the traffic load significantly improves not only the burst-blocking performance of the premium class, but also its sensitivity to lower class traffic variations, We also use the model to dimension and provision the system to guarantee a minimum level of premium-class blocking and premium-class robustness to low-class load variations. [ABSTRACT FROM AUTHOR]

Bursts consist of a varying number of asynchronous transfer mode cells corresponding to a datagram. Here, we generalized weighted fair queueing to a burst-based algorithm with preemption. The new algorithm enhances the performance of the switch service for real-time applications, and it preserves the quality of service guarantees. We study this algorithm theoretically and via simulations. [ABSTRACT FROM AUTHOR]

We present a framework for maximizing the capacity of symmetric bit-rate communication services dominated by Gaussian crosstalk, in particular, digital subscriber line (DSL) services. We solve for optimal transmit power spectral densities (PSDs) that maximize the joint capacity of same-service users and yield significant gains in bit rates (or performance margins) over current schemes. Our results differ from previous work in that we develop transmit spectra in the presence of self-far-end crosstalk in addition to self-near-end crosstalk, present optimal contiguous spectra for practical modulation schemes, and derive optimal spectra under an additional frequency-domain peak-power constraint. Furthermore, by design, the optimal transmit PSDs are spectrally compatible with existing services on neighboring lines. [ABSTRACT FROM AUTHOR]

This paper develops, analyzes, and optimizes a simpler form of dual-branch switch-and-stay combining (SSC), namely, one that relies on the output signal plus noise rather than the instantaneous signal-to-noise ratio (SNR) to trigger the switching between the diversity branches. Analysis supported by numerical results show that the newly proposed postdetection SSC scheme outperforms predetection SSC and this performance gain increases as the channel conditions improve in terms of average SNR and/or severity of fading. In brief, when simplicity of implementation is of primary concern, as is the case, for example, in mobile units, the proposed scheme offers an attractive low-complexity solution to mitigate the deleterious effects of multipath fading. [ABSTRACT FROM AUTHOR]

This letter extends the notion of postdetection switched combining previously introduced by the authors to M-ary orthogonal modulation and proceeds to analyze and evaluate its average bit-error rate performance for the dual-branch case. The particular variation chosen for the switching strategy uses a different model than that previously used for the binary case and although it results in a slightly poorer performance, it nevertheless outperforms conventional (predetection) switched combining for all values of M. Results are obtained for a variety of popular channel models including Rayleigh. Rician, and Nakagami-m fading. Because of its relative simplicity of implementation, the proposed scheme once again offers a very attractive low-complexity solution for mitigating the deleterious effects of multipath fading. [ABSTRACT FROM AUTHOR]

Investigates the non-blocking switching operation of generalized three- stage Clos switching networks in the multirate environment. Determination of the minimum number of second-stage switches required; Consideration of the discrete and continuous bandwidth cases; Derivation of sufficient and necessary conditions.

Considers wide-sense and strict-sense nonblocking conditions for multi-log[sub2] N switching networks with multicast connections. Significance of switching networks composed of log[sub2] N stages to both high-speed electronics and photonic switching; Description of the model used; Presentation of the blocking window concept; Examples of blocking windows in switching networks.

Presents information on a study which considered a high-speed multicast asynchronous transfer mode switch with multiple parallel submemories. Description of the overall switching system architecture; Performance analysis of the switching system in terms of cell loss ratio and average delay; Numerical examples; Conclusions.

Presents information on a study which showed how to take advantage of the multiple-wavelength characteristic of a wavelength-division multiplexing signal to reduce crosstalk in a directional coupler-based photonic switching system. Problem formulation; Crosstalk reduction in multiple-wavelength networks; Conclusions.

Presents information on a study which dealt with the subsystems of the node and how they can be implemented by a photonic switching network. Overview of photonic rearrangeable switching networks; Structure of a rearrangeable network derived from a Banyan network; Sufficient conditions for zero switching element-crosstalk in vertical replication/horizontal expansion networks; Conclusions.

Discusses a study which proposed two efficient time slot assignment algorithms, called the two-phase algorithm for the nonhierarchical and the three-phase algorithm for the hierarchical time-division multiplex switching systems. Designs of the two-phase and three-phase algorithms; Performance analysis; Simulation results.

Presents information on a study which explored the principles of constructing strictly nonblocking directional-coupler-based photonic switching systems under various crosstalk constraints. Methods for building nonblocking Banyan-type networks under specified crosstalk constraints; Nonblocking condition for Banyan-type networks; Conclusions.

A list of the "Institute of Electrical and Electronics Engineers (IEEE) Transactions on Communications" periodical editors, IEEE Officers, IEEE executive staff, and IEEE publishing operations officers as of May 2021 is presented including director of journals M. Zorzi, IEEE general counsel Sophia A. Muirhead, and director of editorial services Kevin Lisankie.

Presents information on a study which evaluated a quasi-optimal scheduling algorithm for input buffered cell-based switches to determine the effectiveness of reservation with preemption and acknowledgement. Methodology of the study; Results of the study; Conclusion.

Presents information on a study which addressed the problem of maximum allowed recovery time in fibers ring architecture. Analysis of Automatic Protection Switching (APS) protocol; Derivation of bounds for the processing time in network nodes; Behavior of APS in case of failures; Conclusion.

Presents information on a study which proposed a modified dilated Benes (MDB) network composed of directional couplers to improve the signal-to-noise ratio characteristics of delated Benes (DB) networks. Experimental details; Comparison between the MDB network and DB networks; Conclusion.

Discusses an approximation for calculating bit error rates in direct code division multiple access (CDMA) radio systems. Use of binary phase shift keyed (BPSK) signaling in the estimation; Features of the BPSK system model; Simplified improved Gaussian approximation.

The article discusses the field of interest of the Communications Society consists of telecommunications including telephone, telegraphy, facsimile, and point-to-point television, by electromagnetic propagation including radio; and submarine cables.