Signal degradation due to physical impairments may result in unacceptable bit-error rates of received signals at the destination. Based on earlier work, we study the impairment-aware quality of service (QoS) provisioning problem in dual-header optical burst switching (OBS) networks that employ two control packets for each data burst. At an OBS node, the proposed algorithm schedule bursts for transmission by searching for available resources using admission control and preemption. The algorithm also verifies signal quality. Simulation results show that this algorithm is effective in providing QoS support in OBS networks while considering physical impairment effects.

Survivable service provisioning design has been an important issue in communication networks. In this work, we study survivable service provisioning using shared path based protection under a scheduled traffic model in wavelength convertible WDM optical mesh networks with Shared Risk Link Groups (SRLGs). In the scheduled traffic model, a set of demands is given, and the setup time and teardown time of a demand are known in advance. The objective is to minimize the total network resources (e.g., the number of wavelength-links) used by working paths and protection paths of the given set of demands while 100% restorability is guaranteed against any single SRLG failure. This problem is known to be NP-hard. We therefore study a time efficient approach to approximating the optimal solution to the problem. Our proposed approach is based on an iterative survivable routing scheme that utilizes a capacity provision matrix and processes demands sequentially. Our simulation results indicate that the proposed ISR-SRLG algorithm achieves excellent performance in terms of the total network resources used.

—Recent technologies in electronics allow to build wireless sensor networks in on or around the human body. Body Area Networks (BAN, is also called Body Sensor Networks) is not only used in medical applications but also has non-medical applications areas such as entertainment, military. This paper reviews the main features of BAN. It also covers the requirements for BAN infrastructure by giving an example of an existing application. We propose a hybrid method to improve existing BAN infrastructure as we call Intelligent Body Sensor Networks (IBSN). We also introduce the new IEEE 802.15.6 standard and point the similarities and differences with existing standards. In addition, we show the numerical results for a lifetime optimized body sensor network requiring a transmission-free area. Our discussion states the trade-off between reliability vs security for such kind of BAN.

AbstractOptical communication is a form of telecommunication that uses light as the transmission medium. An optical communication system consists of a transmitter or a light source that encodes a message into an optical signal, a channel or a waveguide that carries the signal to its destination, and a receiver that reproduces the message from the received optical signal. The development of modern optical communication is indebted to technological breakthroughs and improvements realized in a several areas: light source, materials and manufacturing of low‐loss lightwave guides components and devices essential for effective optical transmission and communication, as well as sophisticated electronics and signal processing techniques.Optical communication has played a key role in increasing the bandwidth of telecommunications networks, especially in the last two decades as the Internet has penetrated our daily lives. The evolution of optical communication and networking has gone through several generations.This article describes and briefly evaluates the basic components of optical communication and networking, the two main types of optical communication bases on the medium or optical waveguide that optical signals traverse:Fiber optical communication andfree space optical communication, as well as optical networking technologies and their applications.

Traffic grooming in optical networks refers to consolidation of subwavelength client connections onto lightpaths. Depending on whether client connections are given in advance or randomly arrive/depart, traffic grooming is classified as static and dynamic. Dynamic traffic grooming has been traditionally performed through establishing/releasing lightpaths online. In this paper, the authors propose an alternate approach to design a static logical topology a priori and then route randomly arriving client connections on it to avoid frequent lightpath setup/teardown. Two problems are considered: 1) minimize resource usage constrained by traffic blocking requirements and 2) maximize performance constrained by given resources. These are formulated as integer linear-programming (ILP) problems. The numerical results show that the resource usage dramatically decreases when the blocking requirement is relaxed, and the grooming performance slowly increases when given more resources. In addition, the number of ports at client nodes has more profound impact on traffic grooming than the number of wavelengths.

Traffic grooming in wavelength division multiplexing (WDM) optical networks controls how to consolidate client calls with sub-wavelength data rates onto lightpaths. It can be classified into static or dynamic traffic grooming depending on whether the client traffic is static or dynamic. The principal problem in traffic grooming is to construct a logical topology to route client traffic over a given physical topology. For dynamic traffic grooming, the logical topology may be dynamically configured, or designed a priori given the stationary traffic demands between client nodes (and reconfigured on relatively large time scale, e.g., on the order of hours, to adapt to traffic demands changes). Both approaches have their pros and cons. This paper studies the latter case and develops a heuristic algorithm to design logical topology, constrained by client traffic blocking probability requirement and the maximum by-pass traffic amount allowed at each client node. We have compared logical topologies designed the heuristic and an ILP model. The heuristic performance is impressive.

Assuming a wireless ad hoc network consisting of homogeneous video users with each of them also serving as a possible relay node for other users, we propose a cross-layer rate-control scheme based on an analytical study of how the effective video transmission rate is affected by the prevailing operating parameters, such as the interference environment, the number of transmission hops to a destination, and the packet loss rate. Furthermore, in order to provide error-resilient video delivery over such wireless ad hoc networks, a cross-layer joint source-channel coding (JSCC) approach, to be used in conjunction with rate-control, is proposed and investigated. This approach attempts to optimally apply the appropriate channel coding rate given the constraints imposed by the effective transmission rate obtained from the proposed rate-control scheme, the allowable real-time video play-out delay, and the prevailing channel conditions. Simulation results are provided which demonstrate the effectiveness of the proposed cross-layer combined rate-control and JSCC approach.

Adaptive multimedia services are very attractive since resources in wireless/mobile networks are relatively scarce and widely variable, and more importantly the resource fluctuation caused by mobility and channel fading can be mitigated using adaptive services. Therefore, there are extensive research activities on Quality of Service (QoS), call admission control, as well as bandwidth degradation and adaptation for adaptive multimedia services in wireless/mobile networks in recent years. However, fairness of bandwidth degradation has largely been ignored in previous work and remains an important issue in adaptive multimedia service provisioning. In this paper, we propose and study proportional degradation service provisioning in wireless/mobile networks that offer multiple classes of adaptive multimedia services. The proposed proportional degradation fairness model guarantees the proportional bandwidth degradation among different classes of services. Two proportional degradation scenarios are studied in this paper. In the first scenario, we study the proportional degradation provisioning with two QoS parameters for adaptive multimedia: the degradation ratio (DR) and the degradation degree (DD). In the second scenario, we study the proportional degradation provisioning with a new QoS parameter for adaptive multimedia: the degradation area (DA). For each scenario, based on the QoS parameters, proportional degradation adaptation algorithms are proposed to approximate the proportional degradation model, to fairly adapt calls' degradations, to utilize the system resource efficiently, as well as to optimize QoS parameters. Performance studies show that in the first scenario, proportional DR has been achieved very well, whereas proportional DD has not been well achieved. In other words, DR outperforms DD in terms of proportional degradation. In the second scenario, proportional DA has been well achieved. Furthermore, bandwidth resources have been efficiently utilized and DA has been minimized. Copyright © 2004 John Wiley & Sons, Ltd.

In heavily congested networks, RED using parameters that provide the best link utilization produces poor response times. In this work, we devise and study the performance of a simple active queue management mechanism called Subsidized RED (SubRED) targeted at short-lived flows or fragile flows (e.g. most HTTP flows) to keep link utilization high while reducing the average flow response time. Our simulation studies have compared the performance of RED and SubRED for a network with HTTP traffic at offered loads less, close to, and more than the link capacity. Simulations show that a subsidy given to a flow provides significantly better performance in terms of HTTP request-reply delays without sacrificing the link utilization. The new scheme is very simple to implement. Combined with our cost-effective flow table based implementation, SubRED does not impose an excessive resource overhead.

Traffic grooming in wavelength division multiplexing (WDM) optical networks studies consolidation of sub-wavelength client traffic onto lightpaths. The principal problem in traffic grooming is to construct a logical topology, and to route client traffic over the constructed logical topology. This paper studies dynamic traffic grooming where client traffic randomly arrives/departs. For dynamic traffic grooming, the logical topology may be dynamically configured, or designed a priori given the stationary traffic demands between client nodes (and reconfigured in relatively large time scale, e.g., on the order of hours, to adapt to changing traffic demands). This paper studies the latter case and formulates it into an integer linear programming (ILP) problem. The formulation minimizes the used network resource, constrained by the requirement of client traffic blocking probability, the maximum by-pass traffic amount allowed at each client node, and the number of ports at each client node. It also integrates wavelength assignment and addresses the most general sparse limited wavelength conversion

In this work, we have proposed and studied efficient online algorithms for shared path protection under dynamic traffic conditions in survivable WDM optical mesh networks. Given a connection request, routing and wavelength assignment of a working path and a protection path for the request is formulated as two integer linear programs based on shared and dedicated path protection, respectively. The objective is to minimize the total cost of additional resources used by the working path as well as the protection path to accommodate a new connection request. We then devise two resource efficient online algorithms using pre-computed candidate routes. The first algorithm uses one candidate working path and one candidate protection path for each newly arrived connection request while the second algorithm may use multiple candidate working paths and/or multiple candidate protection paths. The selection of a pair of paths from candidate routes as well as the assignment of appropriate wavelengths to accommodate a connection request is then jointly considered to minimize the total cost of additional resources. The solutions to the ILP formulations serve as the baseline for evaluating the performance of the proposed algorithms. We have evaluated the effectiveness of the proposed online algorithms via extensive simulations in terms of the connection blocking probability and the revenue earnings improved over the dedicated path protection approach. Our simulations indicate that our proposed computationally efficient online algorithms are able to provide 100% restorability against single failures with a resource efficiency comparable to that of the optimal shared path protection. The results also show that a small increase in the number of candidate working paths or protection paths (from 1 to 3) provides better performance, but a further increase does not improve the performance significantly. Therefore, a proper balance can be struck to achieve both satisfactory performance and efficient computation.

We consider dynamic routing of holding-time aware demands under a sliding scheduled traffic model to satisfy demands' bandwidth and timing requirements. We propose an all hops optimal routing algorithm that iteratively finds all feasible paths of at most h hops at the end of h-th iteration. We prove the correctness and analyze the time complexity of the algorithm.

For video communications over wireless ad-hoc networks, there are fundamentally two different kinds of packet losses: packet losses due to channel over-pumping, where the operating transmission rate is higher than the prevailing channel capacity, and packet losses due to transmission errors. To eliminate the first kind of packet losses, rate-control is necessary in order to adapt to the time-varying channel capacity. For the second kind of packet losses, error-resilient coding techniques should be used. In this paper, we propose a cross-layer rate-control scheme based on an analytical study of how the effective video transmission rate is affected by the prevailing operating parameters. Furthermore, in order to provide error-resilient real-time video delivery over such wireless ad-hoc networks, a cross-layer delay-constrained joint source-channel coding (JSCC) approach, to be used in conjunction with rate-control, is proposed and investigated. Simulation results demonstrate the effectiveness of this combination of cross-layer rate-control and delay-constrained JSCC for supporting error-resilient video delivery over wireless ad-hoc networks operating under a delay constraint.

Sensor networks have emerged as a promising technology for large-scale, real-time monitoring in complex environments. This paper develops in-network algorithms for the detection and tracking of region-based targets and events. We deal with such issues as network topology, event boundary detection, region merging, and region simplification and smoothing. Simulation experiments confirmed that our algorithms are efficient and accurate.

We study traffic grooming in synchronous optical network/ wavelength-division multiplexing (SONET/WDM) bidirectional line-switched ring (BLSR) networks under the uniform all-to-all traffic model with an objective to reduce total network costs (wavelength and electronic multiplexing costs), in particular, to minimize the number of add-drop multiplexers (ADMs) while using the optimal number of wavelengths. We derive a new tighter lower bound for the number of wavelengths when the number of nodes is a multiple of 4. We show that this lower bound is achievable. We then derive new, more general, and tighter lower bounds for the number of ADMs subject to the constraint that the optimal number of wavelengths is used, and propose heuristic algorithms (the circle construction algorithm and the circle grooming algorithm) that try to minimize the number of ADMs while using the optimal number of wavelengths in BLSR networks. Both the bounds and algorithms are applicable to any value of r and for different wavelength granularity g. All previous ADM lower bounds except perhaps that in (Gerstel et al., 1999) were derived under the assumption that the magnitude of the traffic streams (r) is one unit (r = 1) with respect to the wavelength capacity granularity g. Performance evaluation shows that wherever applicable, our lower bounds are at least as good as existing bounds and are much tighter than existing ones in many cases. Our proposed heuristic grooming algorithms perform very well with traffic streams of larger magnitude. The resulting number of ADMs required is very close to the corresponding lower bounds derived in this paper. (C) 2004 Society of Photo-Optical Instrumentation Engineers.

In this paper, we study routing and wavelength assignment of connection requests in survivable WDM optical mesh networks employing shared path protection with partial wavelength conversion while 100% restorability is guaranteed against any single failures. We formulate the problem as a linear integer program under a static traffic model. The objective is to minimize the total cost of wavelength-links and wavelength converters used by working paths and protection paths of all connections. A weight factor is used which is defined as the cost ratio of a wavelength converter and a wavelength-link. Depending on the relative cost of bandwidth and wavelength conversion, the optimization objective allows a proper tradeoff between the two. The proposed algorithm, the shortest-widest-path-first (SWPF) algorithm, uses a modified Dijkstra's algorithm to find a working path and a protection path for each connection request in the wavelength graph transformed from the original network topology. When there are multiple candidate paths that have the same minimum total cost, the path along which the maximum number of converters used at each node is minimized is chosen by the SWPF algorithm. We have evaluated the effectiveness of the proposed algorithm via extensive simulation. The results indicate that the performance of the proposed algorithm is very close to that of the optimal solutions obtained by solving the ILP formulation and outperforms existing heuristic algorithms in terms of total number of converters used and the maximum number of converters required at each node in the network. The proposed algorithm also achieves slightly better performance in terms of total cost of wavelength-links and converters used by all connections. We also investigated shared path protection employing converter sharing. The results show that the technique can reduce not only the total number of converters used in the network but also the maximum number of converters required at each node, especially when a large number of converters are needed in the network. In this study, although the ILP formulation is based on static traffic, the proposed algorithm is also applicable to routing dynamic connection requests.