• Title/Summary/Keyword: Channel Assignment Algorithm

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A Study on Demand Assignment Multiple Access Algorithm based on Seperated Reservation Channel (분리된 예약채널에 의한 요구할당 다중접근방법에 관한 연구)

  • 한정항;송주석
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.7
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    • pp.696-708
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    • 1992
  • In this study, we have several objectives. First, In spite of a fixed bandwidth waste of reservation channel, we maximize the efficiency of transmission channel by the multiple access algorithm that performs channel reservation and data transmission independently, eliminating the frame structure of transmission channel and reserving it by the slot unit . Second, In order to improve the entire system performance, we accommodate the variation of traffic at each earth station more effectively, and accomplish the stable delay characteristics and the equlity of service #or users. For this purpose, we design the satellite channel that consists of reservation channel and transmission channel which are logically separate and operate Independently. We also design a demand assignment multiple access algorithm based on the satellite channel structure.

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Distributed Multi-channel Assignment Scheme Based on Hops in Wireless Mesh Networks (무선 메쉬 네트워크를 위한 홉 기반 분산형 다중 채널 할당 방안)

  • Kum, Dong-Won;Choi, Jae-In;Lee, Sung-Hyup;Cho, You-Ze
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.5
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    • pp.1-6
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    • 2007
  • In wireless mesh networks (WMNs), the end-to-end throughput of a flow decreases drastically according to the traversed number of hops due to interference among different hops of the same flow in addition to interference between hops of different flows with different paths. This paper proposes a distributed multi-channel assignment scheme based on hops (DMASH) to improve the performance of a static WMN. The proposed DMASH is a novel distributed multi-channel assignment scheme based on hops to enhance the end-to-end throughput by reducing interference between channels when transmitting packets in the IEEE 802.11 based multi-interface environments. The DMASH assigns a channel group to each hop, which has no interference between adjacent hops from a gateway in channel assignment phase, then each node selects its channel randomly among the channel group. Since the DMASH is a distributed scheme with unmanaged and auto-configuration of channel assignment, it has a less overhead and implementation complexity in algorithm than centralized multi-channel assignment schemes. Simulation results using the NS-2 showed that the DMASH could improve remarkably the total network throughput in multi-hop environments, comparing with a random channel assignment scheme.

A Channel Assigmnent Algorithm by Controlling the Transmitted Power Level which is based on the Distance between the Cell Site and the Mobile Unit (이동국과 기지국간의 거리에 따라 송신전력을 제어하는 채널할당 알고리즘)

  • 박덕규
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.1 no.1
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    • pp.47-54
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    • 1997
  • New algorithms for frequency channel assignment in small cellular mobile radio system are proposed. The algorithms are for a channel assignment method which control the transmitter power level based on the distance between the cell site and the mobile unit. These algorithms are such that any channel can be used by any cell site and mobile unit, as long as a required threshold level of carrier to interference ratio is maintained. As the cochannel reuse distance decreases, the proposed algorithms have given an increase in capacity in comparison to a fixed channel assignment.

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A Scheduling Scheme using Partial Channel Information for Ad-hoc Networks (Ad-hoc 망에서 채널의 부분정보를 이용한 스케줄링 기법)

  • 신수영;장영민
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.11B
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    • pp.1031-1037
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    • 2003
  • A new scheduling scheme, which uses channel quality information of each flow in Bluetooth system of ad-hoc network for effective bandwidth assignment, has been proposed in this paper. By an effective bandwidth assignment, QoS (Quality of Service) could have been ensured in case of asymmetric data traffic, mixed data transmission, and congested data transmission in a specific channel. The scheduling algorithm determines channel weights using partial channel information of flows. Case studies conducted by NS-2 (Network Simulator 2) and Bluehoc simulator has been presented to show the effectiveness of the proposed scheduling scheme.

Pilot Assignment Algorithm for Uplink Massive MIMO Systems (상향링크 Massive MIMO 시스템에서 파일럿 할당 알고리즘)

  • Jang, Seokju;Kong, Han-Bae;Lee, Inkyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.8
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    • pp.1485-1491
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    • 2015
  • This paper introduces a new pilot assignment algorithm for uplink Massive multiple-input multiple-output (MIMO) systems. Since the conventional pilot assignment algorithm has the performance degradation compared to the optimal algorithm which performs the exhaustive search, we propose a new pilot assignment algorithm using Pre-determined Interference and Pre-determined Desired-term techniques. The proposed algorithm has the low complexity and guarantees negligible performance loss compared to the optimal algorithm. Simulation result verifies that the proposed algorithm achieves a large performance gain over the conventional algorithm.

A Decomposition Approach for Fixed Channel Assignment Problems in Large-Scale Cellular Networks

  • Jin, Ming-Hui;Wu, Eric Hsiao-Kuang;Horng, Jorng-Tzong
    • Journal of Communications and Networks
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    • v.5 no.1
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    • pp.43-54
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    • 2003
  • Due to insufficient available bandwidth resources and the continuously growing demand for cellular communication services, the channel assignment problem has become increasingly important. To trace the optimal assignment, several heuristic strategies have been proposed. So far, most of them focus on the small-scale systems containing no more than 25 cells and they use an anachronistic cost model, which does not satisfy the requirements ity. Solving the small-scale channel assignment problems could not be applied into existing large scale cellular networks' practice. This article proposes a decomposition approach to solve the fixed channel assignment problem (FCAP) for large-scale cellular networks through partitioning the whole cellular network into several smaller sub-networks and then designing a sequential branch-and-bound algorithm that is made to solve the FCAP for them sequentially. The key issue of partition is to minimize the dependences of the sub-networks so that the proposed heuristics for solving smaller problems will suffer fewer constraints in searching for better assignments. The proposed algorithms perform well based on experimental results and they were applied to the Taiwan Cellular Cooperation (TCC) in ChungLi city to find better assignments for its network.

Low Complexity Subcarrier Allocation Scheme for OFDMA Systems (OFDMA 시스템을 위한 저 복잡도 부반송파 할당기법)

  • Woo, Choong-Chae;Wang, Han-Ho
    • Journal of the Institute of Convergence Signal Processing
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    • v.13 no.2
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    • pp.99-105
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    • 2012
  • The focus of this paper is a proposal for a computationally efficient dynamic subcarrier allocation (DSA) algorithm for orthogonal frequency-division multiple access (OFDMA) systems. The proposed DSA algorithm considerably reduces the computational complexity and the amount of channel quality information (CQI) compared to amplitude craving greedy (ACG) algorithms, which use full CQI. At the same time, the performance of the proposed algorithm closely appear to ACG algorithms. Moreover, the authors present a new bandwidth-assignment algorithm produced by modifying bandwidth assignment based on the signal-to-noise ratio (BABS). This modified BABS algorithm enables the proposed DSA algorithm to produce a strong outage performance gain over the conventional scheme.

Performance Analysis of Satellite Communication System for Multimedia Services with Full Connectivity (전연결 멀티미디어 서비스를 지원하는 위성통신 시스템의 성능분석)

  • Teng, Yue;Kim, Doug-Nyum
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.11A
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    • pp.1035-1046
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    • 2005
  • This paper analyzes the channel assignment techniques and their performance in the On Board Processing (OBP) satellite communication system. It suggests the new Continuous Rate Assignment (CRA) and Dynamic Rare Assignment (DRA) for improving the efficiency of channel assignment at the OBP switch. Mathematical analysis and simulation are given to evaluate the system performance. Aggregate real-time and non-real-time services are considered as different classes. Higher priority is given to voice and video real-time services to avoid delay variation. Onboard scheduler uses CRA and DRA ways to arrange the capacity allocation dynamically. An improved algorithm is given to make the channel more efficient by doing some evaluation of the switching matrix.

Optimization of CVQ codebook index for noisy channels (잡음이 존재하는 채널에서 이용되는 분류 벡터 양자화 코드북의 인덱스할당기법)

  • 한종기;김진욱
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.3C
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    • pp.315-326
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    • 2003
  • Abstract In this paper, an improved index assignment procedure is proposed to reduce the channel error effect in a communication system employing classified vector quantization(CVQ). The proposed algorithm consists of two parts: inner index assignment (IIA) and cross index assignment (CIA). The II A reduces the distortion resulting from the error in order bits, presenting the identity of each code vector in a subcodebook. The CIA modifies the indexes assigned by the IIA in such a way that the effect of the channel error occurring in class bits, indicating the class information of the code vector, can be minimized. Simulation results show that the proposed algorithms enable a reliable communication over noisy channels even without employing the channel encoding. Index Terms Classified vector quantization, index assignment.

Matching Pursuit Based Sparse Multipath Channel Estimation for Multicarrier Systems (다중반송파 시스템의 정합추구 기반 희소 다중경로 채널 추정)

  • Kim, See-Hyun
    • Journal of IKEEE
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    • v.16 no.3
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    • pp.258-264
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    • 2012
  • Although linear channel estimation for the frequency selective fading channel has been widely deployed, its accuracy depends on the number of pilots to probe the channel. Thus, it is unavoidable to employ large number of pilots to enhance the channel estimation performance, which essentially leads to the degradation of the transmission efficiency. It even does not utilize the sparseness of the multipath channel. In this paper a sparse channel estimation scheme based on the matching pursuit algorithm and a pilot assignment method, which minimizes the coherence, are proposed. The simulation results reveal that the proposed algorithm shows superior channel estimation performance with fewer pilots to the LS based ones.