• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.684-690
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• 2003

In this paper, a contention-based reservation access control algorithm and a slot allocation algorithm are proposed for non-real-time bursty traffic services in the wireless ATM networks. In order to reduce the collisions of the reservation request packets, the base station scheduler calculates the transmission probability using the number of RAS minislots and the estimated load of the reservation request packets. And it broadcasts the calculated transmission probability over the downlink control channel. Mobile terminals, which have traffic burst, select randomly a RAS minislot and transmit the reservation request packet by the received transmission probability. The reservation request packet contains the number of packets in the buffer. The slot allocation is based on the buffer status of the received reservation request packets. The base station scheduler allocates slots in proportion to the total number of slots that are requested by each terminal.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.117-120
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• 2001

In this paper, a contention-based reservation MAC protocol is proposed for non-real-time bursty traffic services in the wireless ATM networks. In order to reduce the collisions of the reservation request packets, the base station scheduler calculates the transmission probability using the number of RAS minislots and the estimated load of the reservation request packets. And it broadcasts the calculated transmission probability through the downlink control channel. Mobile terminals, which have a traffic burst, select randomly a RAS minislot and transmit the reservation request packet with the received transmission probability. The reservation request packet contains the number of packets in the buffer. The base station allocates slots based on the buffer status of the received reservation request packets.

• Journal of information and communication convergence engineering
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• v.5 no.2
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• pp.93-97
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• 2007

In this paper, centralized access control and slot allocation algorithm is proposed for wireless networks. The proposed algorithm is characterized by the contention-based reservation. In order to reduce the collision probability of reservation request, the base station calculates and broadcasts the transmission probability of reservation requests, and the wireless terminal transmits its reservation request with the received transmission probability. The scheduler allocates the uplink data slots based on the successful reservation requests. Simulation results show that the proposed algorithms can provide high channel utilization, and furthermore, maintains constant delay performance in the heavy traffic environment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2159-2166
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• 2016

In the IEEE 802.11 DCF (Distributed Coordination Function) protocol, the binary exponential backoff algorithm is used to avoid data collisions. However, as the number of stations increases of, the collision probability tends to grow and the overall network performance is reduced. To solve this problem, this paper proposes a data transmission scheme based on the channel reservation method. In the proposed scheme, channel time is divided into reservation period and contention period. During the reservation period, stations succeeded in channel reservation transmit their own data packets in sequence without contention. During the contention period, each station sends its data packets through contentions as in DCF. During both the reservation period and the contention period, each station sends a request for channel reservation for the next reservation period to an AP (Access Point). After receiving such a channel reservation request from each station, the AP decides whether the reservation is succeeded and sends the result via a beacon frame to each station. Performance of the proposed scheme is analyzed through simulations. The simulation results show that the proposed scheme tends to reduce the collision probability of DCF and to improve the overall network performance.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.132-132
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• 2001

본 논문에서는 혼합예약요청(hybrid reservation request) 알고리즘을 적용한 새로운 동적 예약 TDMA 프로토콜을 제안한다. 제안된 혼합 예약 요청 알고리즘은 기존의 랜덤접속방식과 기지국의 중재 없이 단말간 직접 신호교환을 통하여 이웃 단말의 새로운 예약 요청을 대신 전송하는 방식을 혼합해서 사용하는 방법이다. 이 알고리즘은 기존 slotted-ALOHA 방식을 이용한 예약 요청의 비효율성을 개선하여 새로운 단말의 예약 요청실패로 인한 셀 전송지연 및 호 봉쇄 확률(call blocking probability)을 줄이기 위한 목적으로 제안되었다. 제안한 알고리즘은 새로 전송할 데이터를 가진 단말이 많은 경우에 특히 효율적이다. 본 논문에서 제안하는 프로토콜은 모든 종류의 트래픽이 예약을 통한 전송방식으로 전송된다. 즉, 단말들로부터의 예약 요청을 바탕으로, 기지국이 스케줄링을 하여 트래픽 별로 접근 슬랏을 할당해 주는 방식이다. 이 경우, 예약 요청을 하는 방법은 새로 전송을 개시하는 단말과 이미 전송중인 단말의 경우가 다른데, 새로운 전송을 위한 예약이 필요한 단말은 제안하는 알고리즘을 이용하며, 이미 예약에 성공한 단말은 기존에 사용하던 자신의 버스트헤더(burst header)에 피기백(piggybacking)하는 방법을 이용한다. 제안한 알고리즘에 따라, 새로 접속하는 단말이나 새로운 예약 요청이 필요한 단말은 두 단계로 요청을 전송할 수 있다. 첫 번째 단계는 이미 예약에 성공하여 전송중인 이웃단말에게 전송요청신호를 보내 간접적으로 기지국에게 예약을 요청하는 방법이며, 두 번째 단계는 첫 번째 방법이 실패했을 경우 기존의 랜덤접속방법에 참가하는 것이다 먼저 첫 번째 방법에서는 단말이 랜덤접근 구간의 예약요청구간(resonation request)중 하나의 미니 슬랏을 선택해 이웃 단말들에게 한번 방송(broadcast) 한다 이후 ACK 응답구간(ACK receive)에서 응답을 받으면 예약요청성공이라 간주하고, 그렇지 않으면 실패로 판단, 뒤이어 오는 랜덤접근구간(normal random access period)에 참가하여 기지국에게 직접 예약 요청을 한다. 시뮬레이션은 기존 slotted-ALOHA방식으로 랜덤 접속을 할 경우와 제안한 방식과의 성공률을 비교해 제안한 방식의 call blocking probability가 낮음을 보였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.899-906
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• 2003

In this paper, a channel access control algorithm and a slot allocation algorithm are proposed as MAC protocol for multimedia services in TDMA/TDD-based wireless ATM networks. In the proposed protocol, VBR terminals that require real-time services transmit a reservation request through a random access minislot. VBR terminals, which are successfully transmitted the reservation request, transmits the dynamic parameters through a dynamic parameter minislot without contention. On the other hand, ABR terminals transmit a reservation request with contention basis whenever a non-real-time traffic burst is generated. Based on the received dynamic parameters and the number of requested slots, the base station scheduler allocates a dynamic parameter minislot as well as uplink data slots into VBR terminals. Also the scheduler allocates uplink data slots into ABR terminals in proportion to the number of requested slots.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3B
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• pp.191-199
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• 2003

In this paper, a channel access control algorithm and a dynamic slot allocation algorithm are proposed for rt_VBR services and ABR services in the wireless ATM networks. In the proposed algorithm, rt_VBR terminals that require real-time services transmit a reservation request packet by a RAS minislot. An rt_VBR terminal, which transmitted the reservation request packet, transmits the dynamic parameters by DPS minislot without contention. On the other hand, ABR terminals that have a non-real-time traffic burst transfer a reservation request packet with contention basis. Based on the received dynamic parameters, the base station scheduler allocates uplink data slots as well as DPS minislot into rt_VBR terminals.

• The KIPS Transactions:PartC
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• v.8C no.1
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• pp.41-50
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• 2001

With growth of Internet, real time multimedia application services require guarantee of QoS (Quality of Service). However, the existing Internet based on best-effort service is not enough to support those services, so MARS model to support IP multicast over ATM networks and RSVP to provide heterogeneous QoS by resource reservation scheme are proposed. As a simulation result, it is proved that processing delay of MARS is increased and success of resource reservation is decreased as a number of QoS change request of a receiver is increased. Therefore, it is important to provide heterogeneous QoS that distribute a load of MARS caused by convergence of messages and efficiently manage the resource of network as to find out scale of receivers and frequency of QoS change request.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.98-101
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• 1999

Proposed in this paper is an algorithm in which the maximum value of transmission delay due to collision during the reservation request minicell transmission in the uplink period is guaranteed for each traffic type in order to support real time multimedia traffic in wireless ATM environment. Also proposed is a scheme that uses minislots in which dynamic parameters can be transmitted without collision by using only 1-bit piggyback flag of each cell. Setting the piggyback flag is determined according to traffic characteristics and buffer length of each mobile terminal. It is shown that there has been a great improvement in performance of the proposed algorithm through performance analysis using simulation although the algorithm has little overhead.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.74-84
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• 2005

In this paper, a new coexistence mechanism between IEEE 802.15.4 and IEEE 802.11, ACROS (Active Channel Reservation for coexistence), is proposed. The key idea of ACROS is to reserve the channel for IEEE 802.15.4 transmission. During the reservation, IEEE 802.11 transmissions cannot be occurred. Request-to-send/clear-to-send mechanism of IEEE 802.11 is used to reserve channel. The proposed ACROS mechanism is implemented into PC based prototype. By the experiments, the $e{\pm}ciency$ of ACROS is proved.