• 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.

• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.4034-4053
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• 2015

In order to meet various requirements for transmission quality of both primary users (PUs) and secondary users (SUs) in cognitive radio networks, we introduce a channel bonding mechanism for PUs and a channel reservation mechanism for SUs, then we propose a novel spectrum allocation strategy. Taking into account the mistake detection and false alarm due to imperfect channel sensing, we establish a three-dimensional Markov chain to model the stochastic process of the proposed strategy. Using the method of matrix geometric solution, we derive the performance measures in terms of interference rate of PU packets, average delay and throughput of SU packets. Moreover, we investigate the influence of the number of the reserved (resp. licensed) channels on the system performance with numerical experiments. Finally, to optimize the proposed strategy socially, we provide a charging policy for SU packets.

• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.701-708
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• 2005

The mobility prediction algorithm and the channel reservation scheme have been reported as an effective means to provide QoS guarantees and the efficient resource reservation in wireless networks. Among these prediction algorithms, the recently proposed Detailed-ZMHB algorithm makes use of the history of the user's positions within the current cell to predict the next cell, which provides the better prediction accuracy than the others. The handoff prioritizing schemes are proposed to provide improved performance at the expense of an increase in the blocking probability of new calls. In the soft handoff of the CDMA systems, a mobile can communicate via two adjacent cells simultaneously for a while before the actual handoff takes place. In this paper, we propose a new channel reservation scheme making use of the user mobility pattern information in order to reduce the call dropping probability. Our results show that the proposed scheme gives about 67.5-71.1$\%$ lower call dropping probability, compared to the existing scheme.

• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.778-798
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• 2014

This paper proposes a novel exposed-terminal-eliminated medium access control (ETE-MAC) protocol by combining channel reservation, collision avoidance and concurrent transmissions to improve multi-access performance of the multihop wireless networks. Based on the proposed slot scheduling scheme, each node senses the control channel (CCH) or the data channel (DCH) to accurately determine whether it can send or receive the corresponding packets without collisions. Slot reservation on the CCH can be simultaneously executed with data packet transmissions on the DCH. Therefore, it resolves the hidden-terminal type and the exposed-terminal type problems efficiently, and obtains more spatial reuse of channel resources. Concurrent packet transmissions without extra network overheads are maximized. An analytical model combining Markov model and M/G/1 queuing theory is proposed to analyze its performance. The performance comparison between analysis and simulation shows that the analytical model is highly accurate. Finally, simulation results show that, the proposed protocol obviously outperforms the link-directionality-based dual-channel MAC protocol (DCP) and WiFlex in terms of the network throughput and the average packet delay.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.61-64
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• 2003

GPRS is designed for transmitting packet data and supposed to take its radio resource form the pool of channels unused by GSM voice services. In this paper, The GPRS and GSM circuit switched services share the same radio resource. Whenever a channel is not used by circuit switched services, it may be utilized by GPRS. In this paper, the main aim is performance and comparison resource management policies with channel de-allocation in GPRS network. Three resource management policies is voice priority, R-reservation, dynamic reservation.

• Journal of Korea Multimedia Society
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• v.7 no.3
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• pp.340-348
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• 2004

In this paper, we proposed an efficient medium access protocol to share single transmission medium for several stations. There are two well known types of medium access protocols: collision allowance and collision avoidance, and each of them is adopted to their own suitable network with advantage. Our proposed protocol have channel reservation facility based on collision allow medium access protocol, CSMA/CD. In a collision, the stations delay collision with generating pseudo collision signal to reserve channel. Then, the collision terminates and the stations, which reserve channel successfully, participate the next competition with higher medium access probability. We show that the proposed protocol reduced collision times and improved utilization of the channel.

• The KIPS Transactions:PartB
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• v.9B no.6
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• pp.835-844
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• 2002

The number of channels available to a video server is limited since the number of channels a video server can support is determined by its communication bandwidth. Several approaches such as batching, piggybacking and patching have been proposed to reduce I/O demand on the video server by sharing multicast data. Patching has been shown to be efficient in the matter of the cost for VOD systems. Unlike conventional multicast techniques, patching is a dynamic multicast scheme which enables a new request to join an ongoing multicast. In addition, true VOD can be achieved since a new request can be served immediately without having to wait for the next multicast. In this paper. we propose two types of channel reservation patching algorithm : a fixed channel reservation patching and a variable channel reservation patching. To immediately schedule the requests for popular videos, these algorithms reserve the channels of video server for the fixed number of popular videos or for the variable number of popular videos which is determined dynamically according to the load of video server. The performance of the proposed algorithms is evaluated through simulations, and compared with that of simple patching. Our performance measures are average defection rate, average latency, service fairness and the amount of buffered data according to video server loads. Simulation results show that the proposed channel reservation patching algorithms provide better performance compared to simple patching algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1427-1433
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• 2003

This paper presents the routing and wavelength and timeslot assignment problems for a circuit-switched time division multiplexed (TDM) wavelength-routed networks. In this paper, we propose an efficient distributed control protocol for establishing lightpath dynamically. The protocol uses backward reservation to reduce the chance of blocking. We use aggressive reservation method with usable multiple channels and select only one in multiple channel. We show through simulation that the proposed protocol improves the success rate in TDM-based lightpath establishment and the proposed aggressive reservation method improve blocking probability with appropriate reservation channel count.