• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.7
• /
• pp.1732-1743
• /
• 1998

In this paper, we have proposed a channel assignment shceme for the multiple traffic class environment where the traffic volume varies with time. Our basic idea is to assign radio channels considering the characteristics of each traffic class and mobile speed and change the number of allocated channels for each traffic class according to vaiation of traffic volume. To evalute the perfomance of our proposed algorithms, we conducted analyical and simulation studies. We derived new call blocking probability and hand-off failure probability of the proposed scheme analytically. The simulatioh results show that our proposed algorithms can grantee GOS of each traffic class and provide a fairness between the new call and the hand-off call.

• Electronics and Telecommunications Trends
• /
• v.11 no.2 s.40
• /
• pp.1-16
• /
• 1996

사회경제의 발전, 전파이용기술의 진보에 의해 전파이용은 비약적으로 증가하고 있다. 특히, 이동통신분야에서 이동국의 수요 증가는 더욱 현저하여, 제한된 전파자원으로는 이러한 수요를 충족시킬 수 없는 상태이다. 본 고에서는 이러한 문제점에 대처하기 위해, 이동통신에서 주파수 이용효율을 높이는 동적채널할당에 관한 연구동향을 정리하였다.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.22 no.5
• /
• pp.577-582
• /
• 2012

If the mobile station requests the channel allocation in mobile networks, switching center is assigned a channel to mobile station that belong to each base station. Channel allocation schemes is a fixed channel allocation, dynamic channel allocation and a hybrid approach that combines the two forms. To assign a frequency well to use resources efficiently to provide quality service to our customers. In this paper, we proposed method to assign frequencies to minimize interference between channels and to minimizes the number of searching time. The proposed method by the genetic algorithm to improve accuracy and efficiency of the verification steps and reproduction stages were used. In addition, the proposed method by comparing with other methods showed that proposed method is better through the simulations.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.7A
• /
• pp.844-851
• /
• 2004

Various types of error are caused due to many factors of various environment in air interface channel of wireless communications. In this case, the reliability of the channel is much lower than that of wired case. IEEE 802.15.3 high-rate WPAN, which operates in an ad hoc networking environment, is more susceptible to such errors. The problem has been investigated for wireless LANs, for example, as follows. If the queue size of a certain node is longer than that of other nodes, the node estimates that its channel state is bad and the resource of the node is decreased. However this method has a disadvantage that a central controller must always monitor the status. To avoid this disadvantage, in this paper, a new MAC protocol that the throughput of overall piconet is increased by LDS (Link-status Dependent Scheduling) is proposed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.6A
• /
• pp.820-831
• /
• 1999

In this paper, we have compared the performance of a D-TDMA protocol with that of a CDMA protocol, in radio access system for integrated voice/data services.The D-TDMA protocol is based on a generic dynamic channel assignment approach to be followed a combination of “circuit mode” reservation for voice calls, along with dynamic first-come-first served assignment of remaining capacity for data messages. In the CDMA protocol, we have used the voice activity detection to reduce the interface power of other mobiles in internal and external cells, and analyzed the interference power ratio. Also we have computed BER(Bit Error Rate) by using this interference power ratio and evaluated voice blocking probability(voice packet loss probability) and data transmission delay, according to average data length and average data arrival rate.We have found the CDMA protocol achieves comparatively higher performance for short data length, regardless of data arrival rate. Otherwise, the data transmission delay of D-TDMA protocol is shorter than that of the CDMA protocol for long data message.

• Journal of Communications and Networks
• /
• v.18 no.1
• /
• pp.50-64
• /
• 2016

Nowadays, smart meter (SM) technology is widely effectively used. In addition, power allocation (PA) and channel selection (CS) are considered problems with many proposed approaches. In this paper, we will suggest a specific scenario for an SM configuration system and show how to solve the optimization problem for transmission between SMs and the data concentrator unit (DCU), the center that collects the data from several SMs, via simulation. An efficient CS with PA scheme is proposed in the TV white space system, which uses the TV band spectrum. On the basic of the optimal configuration requirements, SMs can have a transmission schedule and channel selection to obtain the optimal efficiency of using spectrum resources when transmitting data to the DCU. The optimal goals discussed in this paper are the maximum capacity or maximum channel efficiency and the maximum allowable power of the SMs used to satisfy the quality of service without harm to another wireless system. In addition, minimization of the interference to the digital television system and other SMs is also important and needs to be considered when the solving coexistence scenario. Further, we propose a process that performs an interference analysis scheme by using the spectrum engineering advanced Monte Carlo analysis tool (SEAMCAT), which is an integrated software tool based on a Monte-Carlo simulation method. Briefly, the process is as follows: The optimization process implemented by genetic evolution optimization engines, i.e., a genetic algorithm, will calculate the best configuration for the SM system on the basis of the interference limitation for each SM by SEAMCAT in a specific configuration, which reaches the solution with the best defined optimal goal satisfaction.

• Proceedings of the Korea Contents Association Conference
• /
• 2009.05a
• /
• pp.682-686
• /
• 2009

The MAC protocol of HiperLAN/2 is based on TDMA/TDD. The radio channels are assigned by AP(Access Point) that is centrally operated. Mobile terminal that data transmission is necessary to uplink requests radio resource to AP through RCH channel. The changing number of RCHs in each MAC frame is important because too many RCHs may result in a waste of radio resources and too few RCHs may result in many access collisions and prolong time that connect to AP. Therefore, number of RCH should be allocated properly according to traffic. From these viewpoint, this paper proposes an advanced scheme that dynamically changed the number of RCH which is based on the number of success and collision of RR message in previous MAC frame. To prove efficiency of proposed scheme, a lots of simulations are conducted and analyzed.

• Journal of Internet Computing and Services
• /
• v.4 no.5
• /
• pp.61-68
• /
• 2003

In this paper, we propose a wireless MAC protocol named APRMA, which is capable of supporting the ABR type data service and Maximizing channel utilization. Data terminals with random data packets are not provided slot reservation with PRMA protocol. That is, slot reservation is applicable to the time constraint voice packet exclusively. But the reservation scheme have to be performed for loss sensitive data packet, and contended their quality of service, Therefore, in wireless MAC, reservation technique has to be used for both voice and data services. So the terminal which wants to request for ABR type service, is allocated a minimum bandwidth from system for the first time, If the system have some extra available bandwidth, ABR terminals would acquire additional bandwidth slot by slot, As a result, APRMA protocol can support the data service with loss sensitivity and maintain their channel utilization high.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1995.04a
• /
• pp.724-728
• /
• 1995

A new dynamic channel assignment (DCA) algorithm with rearrangement for cellular mobile communication systems is suggested. Our DCA algorithm is both traffic and interference adaptive, which is based on the mathematical formulation of the maximum packing under a realistic propagation model. In developing the algorithm, we adopt the Lagrangean relaxation technique that has been successfully used in the area of mathematical programming. Computational experiments of the algorithm reveal quite encouraging results. Although our algorithm primarily focuses on microcellular systems, it can be effectively applied to conventional cellular systems under highly nonuniform traffic distributions and interference conditions.

• Proceedings of the KAIS Fall Conference
• /
• 2009.05a
• /
• pp.425-428
• /
• 2009

본 논문에서는 유럽의 표준화 기구인 ETSI(European Telecommunication Standards Institute)에서 제정한 HiperLAN/2 MAC계층에서 각 단말들의 매체 접근 경쟁방식을 분석하고 아울러 효율적인 자원분배가 이루어지도록 RCH 채널을 할당하는 방법을 분석한다. HiperLAN/2에서는 RCH를 통해서 자원 요청을 받게 되는데 만약 트래픽부하가 큰 경우 RCH가 적게 할당되면 전송지연이 길어질 것이며 반대로 RCH가 필요이상으로 할당되면 수율이 저하되는 문제가 발생한다. 본 논문에서는 이전 프레임에서 성공한 RCH 채널과 충돌한 RCH 채널의 각 크기를 비교하여 현재 프레임의 RCH 채널수를 결정하는 방식을 제안한다. 제안한 방식의 효율성을 입증하기 위해 시뮬레이션을 수행하였다.