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Communications (APCC), 2010 16th Asia-Pacific Conference on

Date Oct. 31 2010-Nov. 3 2010

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Displaying Results 1 - 25 of 97
  • [Copyright notice]

    Page(s): 1
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    Freely Available from IEEE
  • Program

    Page(s): 1 - 18
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    Freely Available from IEEE
  • Committees

    Page(s): 1 - 6
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    Freely Available from IEEE
  • Topology broadcast in maritime mesh networks with directional antennas - A practical approach

    Page(s): 58 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (291 KB) |  | HTML iconHTML  

    The proliferation of wireless transceivers and the availability of unlicensed band has given a boost to the deployment of wireless networks, with IEEE802.11/WiFi being the major driver in this arena. We consider a wireless mesh network designed for long distance communication with a typical deployment scenario of a maritime mesh network. This network uses an antenna system made up of multiple fixed-beamwidth antennas. Through efficient use of directional antennas for both transmission and reception, and spatial reuse in transmission, we are able to realize a high capacity mesh network. In this paper, we present a practical approach to topology dissemination for maritime wireless mesh networks. We validate the design and provide algorithms to demonstrate the viability of the scheme. View full abstract»

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  • Improved area estimates for localization in wireless sensor networks

    Page(s): 40 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (585 KB) |  | HTML iconHTML  

    To accurately determine the location of every sensor in large wireless sensor networks is normally very computation intensive and hence, is not cost-effective. On the other hand, a coarse estimate of the sensors' location is usually sufficient for many applications. The Area Localization Scheme (ALS) has been proposed as a scheme that estimates the position of every sensor within a certain region rather than identifying its exact location. Experimental results have shown that ALS is a promising technique with an accuracy of over 80% of sensors successfully localized. However, the accuracy of the scheme is dependent of the location of the sensors, as the regions into which the sensors are localized are not of uniform sizes. If a sensor is predicted to lie in a small region, then there is a higher probability that the prediction is inaccurate, and vice versa. In this paper, we aim to correct such discrepancy in defining positioning error. We propose to aggregate smaller regions to form more uniform regions within which nodes are localized. This effort improves the overall scheme's accuracy according to some predefined threshold. View full abstract»

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  • Channel feedback reduction schemes for opportunistic scheduling in multicast OFDMA systems

    Page(s): 237 - 242
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (314 KB) |  | HTML iconHTML  

    In this paper, we present new feedback reduction schemes that reduce the feedback load needed for opportunistic scheduling in the multicast OFDMA system. Considering the characteristics of the multicast system that the feedback of the user with the poorest channel condition dictates the transmission rate, we designed the proposed schemes such that it can reduce the total feedback load by sacrificing the feedback of the users with good average channel condition. Specifically, the BS divides the users into two disjoint sets, i.e., the set consisting of the users with poor average channel condition and that consisting of the users with good average channel condition, and makes the users in the former set feed back fine-grained condition of the channels while the users in the latter set feed back coarse-grained condition of the channels. Numerical results reveal that the proposed schemes reduce the total feedback load substantially with a marginal loss of the throughput. View full abstract»

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  • Distributed power allocation for efficient inter-cell interference management in multi-cell OFDMA systems

    Page(s): 243 - 248
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (327 KB) |  | HTML iconHTML  

    In this paper, we present a new power allocation algorithm called distributed inter-cell power allocation (DIPA) that improves the throughput-fairness trade-off without inter-BS coordination for multi-cell OFDMA systems in fast time-varying environment. In order to preclude the affection of instantaneous channel variation, the DIPA is designed to operate in large time scale (or super-frame) based on the long-term average channel condition, as opposed to the user scheduling which is done in short time scale (or frame) based on the short-term instantaneous channel condition. In addition, to reflect the channel conditions of the multiple users, the DIPA is designed to determine the power allocation preferred by each user individually by using a simplified version of the water-filling scheme and then incorporate the individual power allocations into one policy. According to computer simulations the DIPA algorithm turns out to improve both the cell throughput and cell-boundary users' throughput, and increase the performance gain in the practical systems having irregular cell configuration. View full abstract»

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  • Parallel high-performance applications with MPI2Java - A capable java interface for MPI 2.0 libraries

    Page(s): 509 - 513
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1530 KB) |  | HTML iconHTML  

    In this paper, we present the MPI2Java project, which allows researchers to use MPI1 functionalities of the actual MPI 2.0 specification in Java-based applications. We are now able to develop and process parallelised software applications within a modern high-level programming environment. Based on JNI2, a universal and adaptable interface was realised. Thereby, MPI2Java uses the performance-optimised C libraries of MPI to ensure an efficient parallelisation process. Furthermore, the approach supports both 32bit and 64bit hardware platforms. Accordingly, the interface concept offers innovative possibilities in the domain of HPC3 scenarios. A detailed performance analysis with latency and throughput measurements on a parallel computer cluster evaluates the advantages of the proposed interface concept. Based on a massive parallel network simulator for mobile Ad Hoc and sensor topologies - the SimANet framework - additional application scenarios demonstrate the practical capability of MPI2Java in comparison to related MPI implementations for Java. View full abstract»

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  • The capacity of cognitive ad hoc networks

    Page(s): 395 - 400
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (791 KB) |  | HTML iconHTML  

    We analyze the capacity of an ad hoc networks when cognitive radio (CR) is deployed for traffic load reduction. This capacity, the per-link capacity, is defined as an average of Shannon capacities achieved by all links in a route. For this purpose, we propose a generalized ad hoc network model which is based on CR in its retransmission. Given the model, our analysis shows that the capacity is Ω(1/N log N)1 according to the number of nodes N, outperforming the conventional ad hoc network of which the capacity is Ω(1/N2). Further, we can also see that there exists an optimal signal-to-interference ratio (SIR) threshold that maximizes the capacity by controlling the average number of nodes served depending on CR in a link. View full abstract»

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  • Implementation of enhanced lightweight Medium Access (eL-MAC) protocol for wireless sensor network

    Page(s): 267 - 272
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (542 KB) |  | HTML iconHTML  

    Wireless sensor network (WSN) is increasingly being used in a variety of applications which include habitat monitoring, smart health care system, building automation, to name a few. Many approaches were developed for all protocol layers, but an energy-efficient Medium Access Control (MAC) layer remains a key design challenge. MAC with scheduled based architecture provides greater advantage over other designs, such as contention-based and frequency division multiple access (FDMA), in terms of minimizing packet collision, overhearing, idle listening, and over emitting. Reliable and energy efficient data transmission are required to prolong the network lifetime. This paper presents the testbed development of an enhanced lightweight medium access (eL-MAC) protocol which introduces distributed time slot assignment and slotting communication mechanism. Therefore, with eL-MAC, idle listening, overhearing and hidden terminal will be eliminated where nodes transmit in its own time slot and sleep in other time slot if there is no activity. This will reduce energy consumption as nodes are active when transmitting and receiving and idle only in the beacon session. The testbed is developed using TelosB sensor nodes programmed with TinyOS. NesC programming language was used to implement the protocols in the WSN module. Experimental results were compared to the results obtained from simulation. As expected, there is a slight degradation in throughput and packet received ratio in the experiment but is consistent for all values. This concludes that the developed testbed reflects the eL-MAC protocol and has been successfully implemented. View full abstract»

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  • Protocol proxy scheme for emulating OSPF for IP+optical network management

    Page(s): 73 - 77
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (446 KB) |  | HTML iconHTML  

    This paper proposes a protocol proxy scheme that can emulate the open shortest path first (OSPF) protocol in an effective and flexible manner. It is implemented in our developed network emulator, which is used to test network controllers for IP optical network management. In the protocol scheme, OSPF protocol emulation is achieved by combining an OSPF protocol proxy (introduced here) and an OSPF peer state manager based on existing OSPF protocol software. The protocol proxy produces OSPF packets holding link state advertisements with customized extensions including MPLS and GMPLS, while the OSPF peer state manager implements neighbor establishment via the proxy. The protocol proxy has two main functions: rewrite OSPF packets originated by the OSPF peer state manager and generate OSPF packets to inform the updated topology to the network controller. To implement the customized OSPF extensions, only the protocol proxy software need be modified; the existing OSPF software for the OPSF peer state manager is not touched. This makes the implementation of the OSPF emulation easy and flexible. Furthermore, the protocol proxy obtains the network topology information from the resource simulator, which is managed in a centralized manner. This reduces the amount of processing resources required and is scalable in terms of network size. We develop a prototype of the network emulator including OSPF protocol emulation with the protocol proxy scheme. The effectiveness of the protocol proxy scheme is confirmed by an experiment on 40 nodes. View full abstract»

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  • Fair data flows scheduling schema for multihop wireless ad hoc networks

    Page(s): 503 - 508
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB) |  | HTML iconHTML  

    One of the most critical problems in multihop wireless networks is the fair allocation of bandwidth among different nodes. Although there are significant researches on the fairness issues in single-hop wireless networks, research on multihop fairness rarely found in the literature. A user in multi-hop network, besides the contention with other nodes to obtain the channel in physical layer, must find a solution for the inevitable contention between its own and the relayed traffic in the network layer. Accordingly, a suitable mechanism is needed to schedule data flows in network layer fairly. In this paper, a new algorithm is proposed which tries to allocate node's bandwidth fairly between different contention traffic flows. The main purpose of this algorithm, named HBPQ (History Based Priority Queuing) is the prevention of starvation occurrence for any active flow in the network. HBPQ uses a satisfaction function to measure the user's gratifications and tries to bring close the satisfaction of users. If HBPQ is used for flow scheduling in multihop wireless ad-hoc networks, the simulation results show that each active network's flow, receives a throughput proportional to distance between its source and destination and existing traffic load on its traversed path. View full abstract»

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  • On the impact of realistic control channel constraints in UTRAN LTE TDD system

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (557 KB) |  | HTML iconHTML  

    This paper focuses on the Physical Downlink Control Channel (PDCCH) and describes the impact of its realistic constraints on the performance in E-UTRAN LTE TDD system, particularly considering the asymmetric slot resources between downlink and uplink. It is described, when adopting the same PDCCH manager framework in LTE FDD system as in LTE FDD system, the uplink users are not prioritized sufficiently regarding less uplink subframe under most of TDD UL/DL configurations. Therefore, it is proposed, the joint list in the PDCCH manager framework can be adjusted semi-statically to perfectly match TDD UL/DL configurations, and assuming ideal traffic monitoring this can furthermore provide more freedom and flexibility for wider range of UL/DL service requirement, without changing the overall TDD UL/DL configurations. The simulation results proved that the TDD-oriented PDCCH framework can satisfy UL/DL traffic requirement via exploiting the flexibility of joint list based on semi-statistically monitoring and adjustment. View full abstract»

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  • Downlink resource management for OFDMA femtocells using stochastic subchannel allocation

    Page(s): 249 - 254
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1344 KB) |  | HTML iconHTML  

    The Femtocell becomes an effective solution to support indoor high data rate services. The macrocell systems require expensive costs to improve the performance of indoor users. Although the advantage of the femtocells, the co-channel interference between the femtocells and the macrocells is the most significant problem to deploy femtocells. In this paper, a novel downlink resource management algorithm for OFDMA femtocells using the stochastic subchannel allocation is proposed. The stochastic subchannel allocation selects available subchannels used by the femtocells to reduce the interference. Monte-Carlo simulation results show the performance of the proposed algorithm in terms of the average user throughput. View full abstract»

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  • A modulation recognition method based on carrier frequency estimation and decision theory

    Page(s): 6 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (661 KB) |  | HTML iconHTML  

    This paper concerns modulation recognition for blind modulated signals. We use the decision theory, which is popularly used in most researches, to discriminate eleven analog and digital modulated signals with nine key parameters. The carrier frequency is important to calculate some other key parameters. However, for the blind signals, the carrier frequency is unknown, so we propose a method for estimating carrier frequency based on a short frame of intermediate frequency signals. Simulations for different types of analog and digital signals corrupted by band-limited Gaussian White Noise have been carried out. The results show that all types of modulated signals can be determined with success rate greater than 95% when SNR is higher than 10dB. View full abstract»

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  • Joint source and relay optimization for parallel MIMO relays using MMSE-DFE receiver

    Page(s): 12 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (990 KB) |  | HTML iconHTML  

    In this paper, we study the optimal structure of the source precoding matrix and the relay amplifying matrices for multiple-input multiple-output (MIMO) relay communication systems with parallel relay nodes. In particular, a nonlinear decision feedback equalizer (DFE) is used at the destination node, and the minimal mean-squared error (MMSE) criterion is used to detect the transmitted signal at each stream. We show that the optimal source precoding matrix and the optimal relay amplifying matrices have a beamforming structure. Using such optimal source and relay matrices and the MMSE-DFE receiver, a joint source and relay power loading algorithm is developed to minimize the MSE of the signal waveform estimation. Compared with existing algorithms for parallel MIMO relay networks, the proposed source and relay design together with the MMSE-DFE receiver has a significant improvement in the system bit-error-rate performance. View full abstract»

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  • A novel structure of high rate (3,L) regular QC-LDPC codes for magnetic recording channels

    Page(s): 17 - 22
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (145 KB) |  | HTML iconHTML  

    The novel structure of high rate (3,L) regular QC-LDPC codes based on circulant permutation matrices are presented in this paper. The parity-check matrix of the proposed code consists of permutation matrices, their transpose matrices and identity matrices. With this new method, the proposed code is free from girth 4, girth 6, and sometimes girth 8. The construction of parity-check matrix of the proposed codes easily is obtained comparing to those of previously found (3,L) regular QC-LDPC codes. Simulation results on magnetic recording channels show that the BER performance of the proposed codes is very closed to that of other (3,L) regular QC-LDPC codes. View full abstract»

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  • Adaptive intentional connection rerouting for traffic grooming in WDM mesh networks with biological attractor selection

    Page(s): 83 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB) |  | HTML iconHTML  

    In wavelength division multiplexing (WDM) mesh networks, wavelength utilization is limited by the mismatch between the high bandwidth that one wavelength can provide and the relatively low bandwidth request of a single connection. Traffic grooming which grooms multiple connections onto one wavelength is a desirable technique to improve resource utilization. However, with unpredictable traffic demand, the newly arrived request may not be accommodated using remaining resources. Rerouting which reroutes existing connections such that the newly arrived request can be accommodated is an effective approach to further improve network throughput. In this paper, we study adaptive intentional connection rerouting which intentionally triggers rerouting algorithm according to network status, with the aim to reserve maximum resources for future connections. There are two important issues in intentional rerouting scheme: when to trigger rerouting algorithm and the rule to reroute the accommodated connections. The answers to the questions can reduce network blocking probability within an appropriate number of rerouting. In this paper, we propose to use biological attractor selection approach to address the above issues so that rerouting can be performed at the right time to accommodate unpredictable traffic demand. The proposed rerouting scheme can also improve system robustness given its adaptability. The simulations demonstrate the effectiveness of our proposed adaptive rerouting approach. View full abstract»

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  • Delay diversity for direct sequence spread spectrum system to reduce transmitting power in Rayleigh flat-fading channel

    Page(s): 357 - 362
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (412 KB) |  | HTML iconHTML  

    This paper presents a novel technique to save the transmitting power of spread-spectrum communication systems based on the application of delay diversity. The core idea of this delay-diversity system is to delay two spreading sequences that carry the same information of a bit with respect to each other in order to statistically separate the influence of fading on the same bit in time domain. The theoretical bit error rate (BER) expression of the proposed system is derived and verified by simulations. According to the numerical results, it is found that this technique save significant amount of transmitting power, and it may be used to extend the life-time of energy-constrained devices such as sensor nodes in wireless sensor networks. View full abstract»

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  • Modeling the energy performance of object tracking in Wireless Sensor Network using dual-sink

    Page(s): 204 - 209
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1012 KB) |  | HTML iconHTML  

    This paper address the problem of modeling the energy performance by using mobile sinks in Wireless Sensor Networks (WSNs). Mobile sinks can be used to balance energy consumption, however, the frequent location updates of the mobile sinks can lead to data collisions and rapid energy consumption for some specific sensors. In this paper, we explored an optimal barrier coverage based sensor deployment for object tracking WSNs where a dual-sink model was designed by us to evaluate the energy performance of all the static sensors, Static Sink (SS) and Mobile Sink (MS) simultaneously. With the designed MS mobility model that experimentally outperform RM (random movement), PM (peripheral Movement) and SM (Static-base Model), the proposed dual-sink eDSA algorithm was verified by simulations to be more efficient than single static-sink model by approximately half in energy conservation. Moreover, we demonstrate that our results are robust to realistic sensing models and also validate the correctness of our results through extensive simulations. View full abstract»

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  • Potential throughput based access point selection

    Page(s): 470 - 475
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (579 KB) |  | HTML iconHTML  

    Mobile nodes in wireless LANs connect themselves to the Internet via their associated access points (AP). Although more and more APs are being deployed, nodes tend to gather around some common hotspots, contending for few APs and leaving other APs idle. The traffic unbalance affects both per-node throughput and network throughput. In this paper, we aim to solve this problem by AP selection. We jointly consider the two key factors-channel availability and link quality-that determine the achievable throughput of a node, and suggest the potential throughput (PT) metric for AP selection. The PT metric is defined as the maximal throughput that can be achieved by a node if it exclusively occupies the remaining idle channel. In this way, a node can achieve higher throughput by associating with a farther but less used AP and the congestion of the network can be alleviated. The simulation results show that the PT metric can greatly improve the total throughput when nodes are unevenly distributed around APs. The testbed experiments with the off-the-shelf WLAN cards also confirm that the per-node throughput can be effectively improved with the proposed method. View full abstract»

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  • Fuzzy controller for a dynamic window in elliptic curve cryptography wireless networks for scalar multiplication

    Page(s): 458 - 463
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (774 KB) |  | HTML iconHTML  

    The rapid progress of wireless communications and embedded micro-electro-mechanical systems technologies has made wireless sensor networks (WSN) possible. However, the security of the WSN becomes one of the major concerns in its applications. Elliptic curve cryptography (ECC) prominently provides solid potential for wireless sensor network security due to its small key size and its high security strength. However, there is a urgent need to reduce key calculation time to satisfy the full range of potential applications, in particularly for those applications involved wireless sensor networks (WSN). It is well known that scalar multiplication operation in ECC accounts for about 80% of key calculation time on wireless sensor network motes. In this paper we present a fuzzy controller for a dynamic window sizing to allow the calculation processing to run under optimum conditions by balanced case allocating available RAM and ROM at the sensor node within a wireless sensor network. The whole quality of Service (QoS) is improved, in particular the power consuming is more efficiently. The simulation results showed that the average calculation time decreased by approximately 15% in comparison to traditional algorithms in an ECC wireless sensor network. View full abstract»

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  • Experimental evaluation of SKYMESH using terrestrial nodes

    Page(s): 52 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (891 KB) |  | HTML iconHTML  

    This paper proposes a link setup method of “SKYMESH,” which is an ad hoc communication system, temporarily established in the sky by balloons holding communication nodes. The SKYMESH can be used as emergency communication systems when telecommunication infrastructure is damaged for large-scale natural disaster. It was reported that a link between balloons was unstable due to swing of balloons. This paper proposes a link setup method by using terrestrial nodes. A terrestrial node with two directional antennas can be used between balloon nodes to replace an inter-balloon link with two balloon-terrestrial links. The communication distance of the terrestrial-balloon link can be extended with better communication quality. We performed experiments of communication quality measurement in Niigata University campus area from August to September in 2009. As a result, the distance between balloon-to-terrestrial-to-balloon nodes can be extended about ten times as long as that of a link between balloons with stable communication quality. View full abstract»

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  • New high-definition videoconference system for remote lectures connecting 18 National Universities in Japan

    Page(s): 377 - 382
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1488 KB) |  | HTML iconHTML  

    This paper describes construction of a high-definition videoconference system which is connected 18 National Universities. This system is supported two screens with high-definition, to provide videos and sounds in high quality. We can operate a videoconference device, high definition camera, audio and video equipment (an audio amplifier and data projectors, etc.) from a wireless touch panel. A wireless touch panel is connected to an administration system of reservation through a network. This system can reduce a burden of a user, because the user can use it with simple operation for reservation from Web, and a system starts automatically in reservation time and sets it. This system is a beginning in Japan, as for the remote lecture using a high-definition picture connected Japanese universities from the north to the south. View full abstract»

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  • A contender-aware backoff algorithm for CSMA based MAC protocol for Wireless Sensor Network

    Page(s): 261 - 266
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (721 KB) |  | HTML iconHTML  

    Existing contention based nonpersistent medium access control protocols in Wireless Sensor Network (WSN) do not perform well in high contention. Their performances are affected by occurrence of collision due to uniform probability distribution in choosing Time Slot (TS) during backoff period. To address this issue nonuniform probability distribution was proposed. However success rate still drops for higher number of contenders. In this paper we propose CSMA/s (Collision Sense Multiple Access /per Slot based), a new approach in nonuniform contender-aware probability distribution for choosing TS in the backoff period. Rather than taking a premeditated fixed value for contender population size, our proposed scheme embeds neighborhood population size into its bedrock to automatically converge to the actual number of contenders which enables the contender to adaptively choose TS in the backoff period for reducing collision. This method produces better success rate and lower latency for even very high number of contenders. View full abstract»

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