Current Issue : July - September Volume : 2015 Issue Number : 3 Articles : 5 Articles
Energy saving is seldom contemplated in cellular railway communication network because safety is always the main focus.\nHowever, we analyzed train schedules and determined that the cellular railway network had considerable potential for\nenergy saving. We designed a simple train detection strategy using the handover procedure to initiate power saving.\nWe also proposed a flexible and effective solution based on the mealy-type finite state machine to transit the cell state\nbetween an energy-saving mode and a full running mode. The key design principle of the proposed solution consists\nin forming an orthogonal group and cluster, based on network deployment and train schedules, to simplify the state\ntransition. Our evaluations using a real network deployment led to a significant energy saving of up to 33% with different\npower-saving strategies and factors....
With the rapid development of cognitive radio technologies, spectrum sharing becomes a promising approach to\nimproving the efficiency of spectrum utilization and mitigating the spectrum scarcity problem. Previous research on\ncognitive networks argues that secondary users can only work under a low-transmission power in an underlay\nspectrum sharing model, especially when the primary transmitter is far away from the primary receiver. Motivated by\nthe idea of cooperative communications, in this paper, we propose a cooperative framework in which a primary\ntransmitter, being aware of the existence of the secondary network, may select a secondary user that is not in\ntransmitting or receiving mode to relay its traffic. The feasible relay location region and optimal power ratio between\nthe primary network and the secondary network are derived in the underlay spectrum sharing model. Based on the\noptimal power ratio, we derive the maximum achievable transmission capacity of the secondary network under the\noutage constraints from both the primary and the secondary network with or without cooperative relaying. Numerical\nresults indicate that secondary users can achieve a higher transmission capacity with cooperative relaying, and that\nthe capacity gain of the cooperative network is significantly affected by the location of the relay and the network\nsystem parameters....
As very high frequency (VHF) data links are overloaded due to the rise of Automatic Identification System (AIS)\napplications, additional VHF channels and the development of corresponding communication technologies are\nnecessary. For this reason, shipborne ad hoc networks (SANETs) and the medium access (MAC) protocol for SANETs,\nad hoc self-organizing-time division multiple access (ASO-TDMA), have been proposed, which provide ocean-going\nships with diverse data services cost-effectively. In this paper, a new MAC protocol for SANETs, enhanced ASO-TDMA\n(EASO-TDMA), is proposed in order to manage the bottleneck and under-utilization problems resulting from\nASO-TDMA and thus enhances the overall performance of SANETs. To accomplish this, in EASO-TDMA, a ship\nadaptively allocates its time slots according to the number of subscribing ships, which make their communication\nroute to a base station at the shore via the ship, by referring to the routing table. The performance of EASO-TDMA is\ninvestigated through simulations and compared with that of ASO-TDMA. The simulation results indicate that\nEASO-TDMA outperforms ASO-TDMA, regardless of the network conditions, with 25% higher reception success rate,\n25% lower collision rate, and 21% higher channel utilization at maximum. In particular, the end-to-end delay of\nEASO-TDMA is on average 1/12 of that of ASO-TDMA, and this implies that EASO-TDMA can be effective for\ndelay-sensitive data services....
In the past few decades, the development in the field of wireless networks has changed the landscape of wireless communication and network security. This advancement has led to the development of low-power, low-cost sensor nodes that are considerably small in size and applicable in wire variety of applications like, tracking the movements of tanks and troops on the battlefields, tracking the navigation of ships and sub-marines in the sea, monitoring environmental phenomena like earthquakes, tsunamis, forest fire and also in the field of medicine and science. Hence the security of wireless networks has become a major concern, especially for the applications where confidentiality is of peak importance. While the traditional way of protecting the network with firewall and encryption techniques have proven to be insufficient for wireless networks, the need of more secure and scalable architecture of security has alarmed the requirement of Intrusion Detection System (IDS), which are applicable for wireless networks. In this research, Hierarchical based and Energy Efficient Intrusion Detection System has been implemented, which is more secure, scalable and energy efficient compared to other Intrusion detection Systems....
Inclusion of statistical knowledge of the primary user (PU) channel usage had shown to be beneficial in dynamic\nspectrum access. Motivated by this fact, this paper investigated the importance of collecting and using statistics on\nneighboring secondary users (SUs) in selecting channels in addition to the knowledge of PU channel usage. The\npaper assumed that PU traffic characteristics of the channels are included in the radio environment map in the form of\nprobabilistic suffix trees, which is a sequence predictor based on Markov property. In the proposed method, an\nintelligent sequence hopping-based common control channel and a carrier sense multiple access (CSMA)/collision\navoidance (CA)-based medium access control (MAC) protocol were introduced. As shown in the paper, selecting\nchannels using statistics of both the neighboring SUs and PUs reduced the number of packet collisions compared to a\nscheme which only uses PU statistics. Furthermore, the simulation results showed that the scheme proposed had\nbetter throughput performance with respect to both the random channel selection scheme and the scheme which\nonly uses PU statistics while having less training complexity...
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