• Title/Summary/Keyword: multi-access channel

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Performance Analysis of Opportunistic Spectrum Access Protocol for Multi-Channel Cognitive Radio Networks

  • Kim, Kyung Jae;Kwak, Kyung Sup;Choi, Bong Dae
    • Journal of Communications and Networks
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    • v.15 no.1
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    • pp.77-86
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    • 2013
  • Cognitive radio (CR) has emerged as one of effective methods to enhance the utilization of existing radio spectrum. Main principle of CR is that secondary users (SUs) are allowed to use the spectrum unused by primary users (PUs) without interfering PU's transmissions. In this paper, PUs operate on a slot-by-slot basis and SUs try to exploit the slots unused by PUs. We propose OSA protocols in the single channel and we propose an opportunistic spectrum access (OSA) protocols in the multi-channel cognitive radio networks with one control channel and several licensed channels where a slot is divided into contention phase and transmission phase. A slot is divided into reporting phase, contention phase and transmission phase. The reporting phase plays a role of finding idle channels unused by PUs and the contention phase plays a role of selecting a SU who will send packets in the data transmission phase. One SU is selected by carrier sense multiple access / collision avoidance (CSMA/CA) with request to send / clear to send (RTS/CTS) mechanism on control channel and the SU is allowed to occupy all remaining part of all idle channels during the current slot. For mathematical analysis, first we deal with the single-channel case and we model the proposed OSA media access control (MAC) protocol by three-dimensional discrete time Markov chain (DTMC) whose one-step transition probability matrix has a special structure so as to apply the censored Markov chain method to obtain the steady state distribution.We obtain the throughput and the distribution of access delay. Next we deal with the multi-channel case and obtain the throughput and the distribution of access delay by using results of single-channel case. In numerical results, our mathematical analysis is verified by simulations and we give numerical results on throughput and access delay of the proposed MAC protocol. Finally, we find the maximum allowable number of SUs satisfying the requirements on throughput and access delay.

UMMAC: A Multi-Channel MAC Protocol for Underwater Acoustic Networks

  • Su, Yishan;Jin, Zhigang
    • Journal of Communications and Networks
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    • v.18 no.1
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    • pp.75-83
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    • 2016
  • In this paper, we propose a multi-channel medium access control (MAC) protocol, named underwater multi-channel MAC protocol (UMMAC), for underwater acoustic networks (UANs). UMMAC is a split phase and reservation based multi-channel MAC protocol which enables hosts to utilize multiple channels via a channel allocation and power control algorithm (CAPC). In UMMAC, channel information of neighboring nodes is gathered via exchange of control packets. With such information, UMMAC allows for as many parallel transmissions as possible while avoiding using extra time slot for channel negotiation. By running CAPC algorithm, which aims at maximizing the network's capacity, users can allocate their transmission power and channels in a distributed way. The advantages of the proposed protocol are threefold: 1) Only one transceiver is needed for each node; 2) based on CAPC, hosts are coordinated to negotiate the channels and control power in a distributed way; 3) comparing with existing RTS/CTS MAC protocols, UMMAC do not introduce new overhead for channel negotiation. Simulation results show that UMMAC outperforms Slotted floor acquisition multiple access (FAMA) and multi-channel MAC (MMAC) in terms of network goodput (50% and 17% respectively in a certain scenario). Furthermore, UMMAC can lower the end-to-end delay and achieves a lower energy consumption compared to Slotted FAMA and MMAC.

Multi-Access Points Transmit Power Control Algorithm in Consideration of the Channel Estimation Error and the Multi Rate Service (채널추정 에러와 다중 전송률 서비스를 고려한 다수 개의 엑세스포인트 전송전력제어 알고리즘)

  • Oh, Changyoon
    • Journal of Korea Society of Industrial Information Systems
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    • v.25 no.4
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    • pp.39-47
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    • 2020
  • We propose a multi-access points transmit power control algorithm in consideration of the channel estimation error and the multi-rate service. In the real communication systems, the channel estimation at the receiver side is imperfect due to limited number of pilot symbol usage. Furthermore, the multi-rate service is supported. We theoretically prove the uniqueness and the convergence of the proposed algorithm in multi-rate service environment. The proposed algorithm composes of one inner loop part and one outer loop part. Simulation results show that 1) the inner loop algorithm guarantees convergence of the transmit power level and the multi-rate service, 2) the outer loop algorithm compensates for the channel estimation error.

PERFORMANCE OF MYOPIC POLICY FOR MULTI-CHANNEL DYNAMIC SPECTRUM ACCESS NETWORKS

  • Lee, Yutae
    • East Asian mathematical journal
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    • v.30 no.1
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    • pp.23-29
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    • 2014
  • To solve inefficient spectrum usage problem under current static spectrum management policy, various kinds of dynamic spectrum access strategies have appeared. Myopic policy, which maximizes immediate throughput, is a simple and robust strategy with reduced complexity. In this paper, we present a simple mathematical model to evaluate the saturation throughput and medium access delay of a myopic policy in the presence of multiple channels.

A Novel Multi-channel MAC Protocol for Ad hoc Networks

  • Dang, Duc Ngoc Minh;Quang, Nguyen Tran;Hong, Choong-Seon
    • Proceedings of the Korean Information Science Society Conference
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    • 2012.06d
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    • pp.187-189
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    • 2012
  • The medium access control (MAC) protocol is designed only for single channel in the IEEE 802.11 standard. That means the throughput of the network is limited by the bandwidth of the single channel. The multiple channels can be exploited to get more concurrent transmission. In this paper, we propose a novel Multi-channel MAC that utilizes the channel more efficiently than other Multi-channel MAC protocols.

A Control Channel Access Scheme for Clustered Multi-interface Multi-hop Cognitive Radio Networks (클러스터 형태의 다중 인터페이스 다중 홉 인지 라디오 네트워크를 위한 제어 채널 접근 기법)

  • Lee, Ji-Wun;Jeon, Wha-Sook;Jeong, Dong-Geun
    • Journal of KIISE:Information Networking
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    • v.37 no.4
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    • pp.301-306
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    • 2010
  • We propose the control channel access scheme for multi-interface multi-hop cognitive radio (CR) environment having a cluster structure. Due to the difficulty of obtaining common channels across the entire CR network, most multi-interface multi-hop CR networks put the control channel outside the CR bandwidth and dedicate one network interface to it in order to exchange the control information such as the activation of licensed users. However, this will be the waste of the network interface. Our focus is how to alternate between the control and the data channel without multichannel hidden node problem under the cluster structure where CR nodes connect with neighbors through multiple data channels. By using simulation, we evaluate the performance of the proposed scheme. The results show that the proposed scheme achieves higher network throughput than the dedicated scheme where one network interface card should dedicate to the control channel and cannot be used for data transmission.

Multi-Channel MAC Protocol Using Statistical Channel Utilization for Cognitive Networks

  • Xiang, Gao;Zhu, Wen-Min;Park, Hyung-Kun
    • Journal of information and communication convergence engineering
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    • v.8 no.3
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    • pp.273-276
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    • 2010
  • Opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. The proposed protocol's simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.

Unified Optimal Power Allocation Strategy for MIMO Candidates in 3GPP HSDPA

  • Kim, Sung-Jin James;Kim, Ho-Jin;Lee, Kwang-Bok
    • ETRI Journal
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    • v.27 no.6
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    • pp.768-776
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    • 2005
  • We compare the achievable throughput of time division multiple access (TDMA) multiple-input multiple-output (MIMO) schemes illustrated in the 3rd Generation Partnership Project (3GPP) MIMO technical report, versus the sum-rate capacity of space-time multiple access (STMA). These schemes have been proposed to improve the 3GPP high speed downlink packet access (HSDPA) channel by employing multiple antennas at both the base station and mobile stations. Our comparisons are performed in multi-user environments and are conducted using TDMA such as Qualcomm's High Data Rate and HSDPA, which is a simpler technique than STMA. Furthermore, we present the unified optimal power allocation strategy for HSDPA MIMO schemes by exploiting the similarity of multiple antenna systems and multi-user channel problems.

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A Survey on Communication Protocols for Wireless Sensor Networks

  • Jang, Ingook;Pyeon, Dohoo;Kim, Sunwoo;Yoon, Hyunsoo
    • Journal of Computing Science and Engineering
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    • v.7 no.4
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    • pp.231-241
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    • 2013
  • Improvements in wireless sensor network (WSN) technology have resulted in a large number of applications. WSNs have been mainly used for monitoring applications, but they are also applicable to target tracking, health care, and monitoring with multimedia data. Nodes are generally deployed in environments where the exhausted batteries of sensor nodes are difficult to charge or replace. The primary goal of communication protocols in WSNs is to maximize energy efficiency in order to prolong network lifetime. In this paper, various medium access control (MAC) protocols for synchronous/asynchronous and single/multi-channel WSNs are investigated. Single-channel MAC protocols are categorized into synchronous and asynchronous approaches, and the advantages and disadvantages of each protocol are presented. The different features required in multi-channel WSNs compared to single-channel WSNs are also investigated, and surveys on multi-channel MAC protocols proposed for WSNs are provided. Then, existing broadcast schemes in such MAC protocols and efficient multi-hop broadcast protocols proposed for WSNs are provided. The limitations and challenges in many communication protocols according to this survey are pointed out, which will help future researches on the design of communication protocols for WSNs.

SPMC-MAC : Slim Preamble Multi-Channel MAC Protocol with Transmission Power Control in Wireless Sensor Networks (무선 센서 네트워크에서 다중 채널과 전송세기 제어를 이용한 맥 프로토콜)

  • Yoon, Jang-Muk;Bahk, Sae-Woong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.10B
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    • pp.876-884
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    • 2008
  • In this paper, we propose an asynchronous MAC protocol to minimize energy usage and to maximize data throughput for a wireless sensor network in multi channel environments. Our proposed SPMC-MAC (Slim Preamble Multi-Channel Media Access Control) adopts the preamble sliming mechanism proposed in [6] that takes advantage of the knowledge about the wakeup time of the receiver node. The preamble contains the receiver's ID and a randomly selected channel ID for data communication, and it is transmitted over a dedicated common channel. The power control has the benefit of keeping an appropriate number of nodes with the communication range, resulting in reduced collision and interference. We compare our SPMC-MAC and X-MAC extensively in terms of energy consumption and throughput using mathematical analysis and simulation.