IET Networks
Print ISSN
2047-4954
Online ISSN 2047-4962
Online ISSN 2047-4962
IET Networks covers the fundamental developments and advancing methodologies to achieve higher performance, optimized and dependable future networks. IET Networks is particularly interested in new ideas and superior solutions to the known and arising technological development bottlenecks at all levels of networking such as topologies, protocols, routing, relaying and resource-allocation for more efficient and more reliable provision of network services.
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Time-dependent spectrum resource sharing in flexible bandwidth optical networks
- Author(s): J. Zhang; J. Zhang; Y. Zhao; X. Wang
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p.
189
–198
(10)
In recent years, many researches have been focused on the flexible bandwidth optical networks in which the spectrum can be flexibly assigned in an efficient way. Thanks to the finer granularity in optical layer, flexible bandwidth optical networks achieve higher spectrum efficiency than wavelength routed optical networks. This benefit offers a good choice to provide connections between IP routers which the converged IP traffic flow is variable and time-dependent. In most cases, network operators often over-allocate network capacity to time-dependent traffic. However, it causes wasted of resource when the traffic volume becomes low at some time periods. To utilise the spectral resource effectively, the authors propose a novel time-dependent spectrum resource sharing (T-SRS) model in flexible bandwidth optical networks, in which the idle spectrum can be reused by other traffics. An interference factor (IF) is also introduced to evaluate the performance of T-SRS model. The authors formulate the problem using the integer linear programming (ILP) formulations to minimise IF optimally. Two efficient heuristic algorithms are proposed based on the T-SRS model and compared with ILP results. The numerical simulations show that more idle spectrum can be reused by reducing the IF.
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IPv6 auto-configuration VANET cross layer design based on IEEE 1609
- Author(s): C.-S. Li; H.-C. Chao
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p.
199
–206
(8)
In 1999, the Federal Communications Commission of the US granted 75 MHz bandwidth at 5.850–5.925 GHz frequency band for intelligent transportation system wireless communication between vehicles and roadside infrastructures to improve automotive user driving safety and comfort. For fast IPv6 global-link address auto-configuration in vehicular ad-hoc network (VANET), IEEE 1609.3 defines a frame ‘Wireless Access effort in the Vehicular Environment (WAVE) service acknowledge’ to replace router advertisement (RA); however, it violates the Transmission Control Protocol (TCP)/Internet Protocol (IP)-layered design. Hence the authors propose two cross-layer designs called router RA proxy and host RA proxy for WAVE systems to achieve quick IPv6 address auto-configuration, and both the designs are simulated in OPNET.
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Radio environment aware stable routing scheme for multi-hop cognitive radio network
- Author(s): S. Parvin; T. Fujii
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p.
207
–216
(10)
Routing is a challenging issue when dealing with the multi-hop cognitive radio networks (CRNs). The stability of a route is highly influenced by the behaviour of the primary user (PU). The more frequently PU changes its activity, the less stable spectrum availability the cognitive user has. This causes tremendous stability fluctuation of the route in CRNs. The radio environmental issues that affect the route stability for the CRNs are: primary exposed node (PEN) and primary hidden node (PHN). These issues degrade the route stability and are the most important problems in the CRNs. To address this stability problem, the authors propose a radio environment aware stable routing (RASR) scheme for multi-hop CRNs. In order to mitigate the PEN and PHN problems, a channel priority list is kept locally by each secondary user. RASR can evaluate the route stability and can find appropriate route by defining a routing metric, which uses the second smallest eigenvalue of the Laplacian matrix. The proposed routing metric takes into account the route stability, path length and the activity of the PU. Simulation result shows that the proposed RASR enhances the route stability compared with the conventional routing schemes ad hoc on-demand distance vector with hop-count routing metric, and connectivity-based routing scheme Gymkhana.
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Effective border gateway protocol protection that does not require universal adoption of a public key infrastructure
- Author(s): D. Comer; P. Singh; S. Vasudevan
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p.
217
–228
(12)
Although it is fundamental to inter-domain routing in the Internet, the border gateway protocol (BGP) is susceptible to both misconfiguration and malicious attacks. Prefix-hijacking problems arise when an Internet service provider incorrectly advertises a route to one or more prefixes, and path hijacking problems arise when an advertisement contains an incorrect path. Several proposals have been made for ways to avoid or at least ameliorate catastrophic outcomes (such as black holes and man-in-the-middle attacks) that can occur as the result of a hijack. The techniques can be divided into two broad categories: those that use an external authority to validate incoming BGP information and those that validate incoming BGP messages against a historical record of past BGP advertisements. The study begins by defining terms, reviewing the existing methods, and explaining approaches used for external validation. It considers the effectiveness of each mechanism. The study then proposes a hybrid scheme that combines the use of an external authority and historical validation to improve effectiveness. It discusses the difference between our approach and validation using certificates plus a public key infrastructure. We show that it is possible to construct a hybrid hijack deterrent scheme that does not depend on a public key infrastructure and yet remains as effective as schemes that rely on the resource public key infrastructure and certificates to validate path origins. We present measurements that show the cost of maintaining a local cache of registry information and a local cache of historical data as well as the effectiveness of our approach.
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Proactive autonomic load uniformisation with mobility management for wireless Internet Protocol (IP) access networks
- Author(s): A. Jaron; P. Pangalos; A. Mihailovic; A.H. Aghvami
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p.
229
–238
(10)
The agent micro-mobility protocols, such as Hierarchical Mobile IPv6 and Proxy Mobile IPv6, have become leading contenders for providing micro-mobility support to mobile nodes (MNs). The presence of mobility agents (MAs) in these networks can lead to constrained routing and create areas of bottleneck around the MAs. When an MA is integrated in the access network all traffic is forced to flow through that MA potentially over-utilising paths along the MA, whereas other paths of the network remain under-utilised. For the efficient deployment of such networks, optimal and robust MA selection and load balancing mechanisms are required. This study introduces proactive autonomic load uniformisation, a self-managed load balancing scheme in which the congestion caused by MAs is reduced leading to better utilisation of the network resources. Assuming that the network supports multiple MAs, the proposed solution selects the optimal MAs by distributing optimally the incoming load within the network while at the same time maintaining the quality of service requirements for the MNs. The results show that the congestion is lowered by 25% within the network and the load is distributed uniformly across the MAs.
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Field-programmable gate array-based software-defined radio for millimetre-wave single-carrier transmission
- Author(s): K. Sobaihi; A. Hammoudeh; D. Scammell
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p.
239
–248
(10)
Recently, variants of wireless local and personal area networks (WLANs/WPANs) have emerged with different communication protocols that require extremely high-performance signal processing techniques. Taking advantage of the recent advances in the programmable and reconfigurable devices, the implementation of reliable, high data-rate software-defined radios that support multiple protocols has become possible. This study introduces the design and hardware implementation details of a software-defined radio using a field-programmable gate array platform. The implemented software radio consists of a baseband single-carrier transceiver that is compliant with the IEEE 802.15.3c standard for the millimetre-wave wireless personal area network (WPAN), results of bit-error-rate against signal-to-noise ratio are presented and line-of-sight transmission has been demonstrated over millimetre-wave indoor channel.
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Energy-efficient adaptive routing in wireless ad hoc and mesh networks
- Author(s): A.M. Akhtar; M.R. Nakhai; A. Hamid Aghvami
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p.
249
–256
(8)
In this study, the authors focus on energy-efficient routing in wireless ad hoc and mesh networks. Since the existing energy-efficient routing algorithms are fixed and unaware of the channel fading dynamics, they may be suitable if the antennas at network nodes are situated in very high altitudes and have highly directive links. Although, some physical experimental results suggest that even in such scenarios the effect of fading may not be negligible. Particularly in urban areas, the impact of fading cannot be ignored. Thus, when deployed in real world scenarios, current energy-efficient routing algorithms suffer from severe performance degradation in terms of power consumption. In this study, the authors first introduce fading aware decision metrics that help the current node select the optimal next hop destination. Then, using these metrics, the authors propose a power saving routing (PSR) algorithm that takes into account the multipath fading effect. The algorithm is optimised based on the location knowledge of the nodes and the localised channel condition of each node. Simulation results confirm that the proposed algorithm outperforms the existing well-known PSR algorithm.
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Partial messages ordering by double confirmation in wireless sensor and actuator networks
- Author(s): C.-C. Tuan; Y.-C. Wu
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p.
257
–268
(12)
Message ordering is an important issue in wireless sensor and actuator networks, since actuators may take error decisions or actions based on the fail messages ordering from sensors. However, it is difficult to ensure that there is no prior message transmitted in the network, whereas later messages arrived at the actuators. An ordering by confirmation (OBC) algorithm was proposed to address this issue. Nevertheless, the OBC algorithm could not guarantee the rate of correct messages ordering up to 100%. To solve this problem, an ordering by double confirmation (OBDC) algorithm was proposed to guarantee the rate of correct messages ordering up to 100%. However, the OBDC algorithm needs to use more time than the OBC algorithm. Moreover, both the OBC and OBDC algorithms do not address the partial messages ordering issue, since some messages are not co-related to themselves. Therefore the authors propose a partial messages ODBC (POBDC) algorithm to guarantee the rate of correct messages ordering up to 100% with less time. Messages in the POBDC algorithm are divided into independent and partial messages. The simulation results showed that the POBDC algorithm guarantees that the rate of correct messages ordering is 100% and spends less time than the OBDC algorithm.
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High-performance routers with multi-stage multi-layer switching and single-stage shared buffering
- Author(s): F. Wang; M. Hamdi; D. Lin
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p.
269
–280
(12)
High-performance routers for next generation networks are required to scale with the increasing ‘port number’ due to developments of various network access technologies. It has been common practice to build scalable multi-stage multi-layer switches in circuit switching. For packet switches, however, researchers have so far had no consensus on how to employ the multi-stage multi-layer architecture. The underlying reason is that packet switching performance is much affected by their buffering strategies. In single-stage crossbar routers, the well-understood combined-input-output-queuing (CIOQ, at one extreme is input queuing, at the other is output queuing) has rich and growing theories about its performance analysis. In multi-stage multi-layer switches, however, researchers were not much clear about how or whether it is necessary to introduce buffers into the middle stages. In this study, the authors investigate this problem and propose to buffer all packets in the central stage instead of the input side. By making all buffers fully shared (in a distributed way), we show that routers with multi-stage multi-layer switching and single-stage shared buffering (MMS-SSB) are ‘scalable’ in terms of not only the hardware cost, but the efficient scheduling algorithms as well. In addition, both analysis and simulations show that performance of the MMS-SSB switch with our proposed scheduling algorithms is ‘independent’ of outside traffic.
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Enhanced hybrid coordination function controlled channel access-based adaptive scheduler for delay sensitive traffic in IEEE 802.11e networks
- Author(s): S. Madhar Saheb; A.K. Bhattacharjee; P. Dharmasa; R. Kar
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p.
281
–288
(8)
IEEE 802.11e wireless local area networks specify the hybrid coordination function (HCF) controlled channel access (HCCA) method, which includes reference scheduling and an admission control. In the HCCA scheduler, channel interference, bursty traffic streaming and packet loss cause insufficiency in the strict periodic transmission opportunity (TXOP) allocation scheme. It provides quality of service by using the most severe delay requirement and thus over allocating the bandwidth. In order to overcome the disadvantages of HCCA, this study proposes an enhanced HCCA-based adaptive scheduler for delay sensitive traffic. In the proposed scheme, the sender includes the tolerable loss limit along with the traffic specification to estimate the packet loss rate. To estimate the queue size at the end of the previous TXOP, the proposed scheme first calculates the bit error rate based on the specified channel conditions. The mean application data rate for the next TXOP is evaluated. Expected delay and the per hop maximum delay are computed. The rest of per hop delay is calculated based on the remaining delay and the remaining hops of a packet. Then, the queued packets are checked for the required bandwidth and scheduled, so that the probability for transferring the delayed packets can be increased.
