• 한국통신학회논문지
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• 제19권9호
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• pp.1748-1758
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• 1994

최근에 이동통신의 수요가 급격히 증가하고 있으며, 음성뿐만 아니라 종합정보통신망(ISDN)에서 제공되는 데이터, 팩스, 영상 등의 비음성계 서비스가 요구되고 있다. 따라서 본 논문에서는 PCS 시스템의 기본 핵심기술로 활용될 수 있는 디지털 셀룰러 CDMA 시스템용 음성/데이터 집적 서비스 방안들을 제시하고 컴퓨터 심뮬레이션을 통하여 각 집적 서비스 방안의 성능을 비교 분석한다. 컴퓨터 시뮬레이션 결과, CDMA의 한 논리채널을 여러 단말기가 할당받아 PRMA 방식으로 경쟁하는 PR-CDMA 음성/데이타 집적 서비스 방안이 CDMA 방식의 단점인 고정 채널갯수의 한계와 채널이용율의 저하를 극복할 수 있어 전용단말기나 음성/데이타 집적단말기를 이용한 광대역 CDMA 음성/데이타 집적서비스 방안 보다 모든 면에서 우수한 성능을 나타냄을 알 수 있었다.

• Journal of information and communication convergence engineering
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• 제5권2호
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• pp.88-92
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• 2007

In this paper, an SS-RRA protocol that is based on Code Division Multiple Access is proposed and analyzed under the integrated voice and data traffic load. The backward logical channels consist of slotted time division frames with multiple spreading codes per slot. The protocol uses a reservation mechanism for the voice traffic, and a random access scheme for the data traffic. A discrete-time, discrete-state Markov chain is used to evaluate the performance. The numerical results show that the performance can be significantly improved by a few distinct spreading codes.

• ETRI Journal
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• 제23권2호
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• pp.52-60
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• 2001

In this paper, a medium access control protocol is proposed for integrated voice and data services in wireless local networks. Uplink channels for the proposed protocol are composed of time slots with multiple spreading codes per slot based on slotted code division multiple access (CDMA) systems. The proposed protocol uses spreading code sensing and reservation schemes. This protocol gives higher access priority to delay-sensitive voice traffic than to data traffic. The voice terminal reserves an available spreading code to transmit multiple voice packets during a talkspurt. On the other hand, the data terminal transmits a packet without making a reservation over one of the available spreading codes that are not used by voice terminals. In this protocol, voice packets do not come into collision with data packets. The numerical results show that this protocol can increase the system capacity for voice service by applying the reservation scheme. The performance for data traffic will decrease in the case of high voice traffic load because of its low access priority. But it shows that the data traffic performance can be increased in proportion to the number of spreading codes.

• 산업경영시스템학회지
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• 제29권4호
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• pp.100-106
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• 2006

We analyze a voice/data integrated traffic model of the cellular mobile communication system with hybrid guard channels for voice and handoff calls. In a multi-service integrated wireless environment, quality of service guarantee is crucial for smooth transportation of real time information. Real time voice traffic requires a guaranteed upper bounded on both delay and packet error rate, whereas data traffic does not. Voice traffic has high transmission priority over data packets. Thus one of the important problems is the design of admission control schemes which can efficiently accommodate the differential quality of service requirements. In this paper, a hybrid guard channel scheme is considered in which arriving calls are assigned channels as long as the number of busy channels in the cell is below a predetermined first threshold. When the number of busy channels reaches the first threshold, new originating data calls are queued in the infinite data buffer. Then reaches second threshold, only handoff calls are assigned the remaining channels and new originating voice calls are blocked. We evaluate the system by a two-dimensional Markov chain approach and generating function method and obtain performance measures included blocking probability and forced termination probability.

• Journal of Information Processing Systems
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• 제2권2호
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• pp.107-113
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• 2006

It is essential to guarantee a handoff dropping probability below a predetermined threshold for wireless mobile networks. Previous studies have proposed admission control policies for integrated voice/data traffic in wireless mobile networks. However, since QoS has been considered only in terms of CDP (Call Dropping Probability), the result has been a serious CBP (Call Blocking Probability) unfairness problem between voice and data traffic. In this paper, we suggest a new admission control policy that treats integrated voice and data traffic fairly while maintaining the CDP constraint. For underprivileged data traffic, which requires more bandwidth units than voice traffic, the packet is placed in a queue when there are no available resources in the base station, instead of being immediately rejected. Furthermore, we have adapted the biased coin method concept to adjust unfairness in terms of CBP. We analyzed the system model of a cell using both a two-dimensional continuous-time Markov chain and the Gauss-Seidel method. Numerical results demonstrate that our CAC (Call Admission Control) scheme successfully achieves CBP fairness for voice and data traffic.

• 한국통신학회논문지
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• 제29권10B호
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• pp.866-879
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• 2004

본 연구논문에서는 소비자의 서비스 품질에 따른 지불의사를 고려하여 음성/데이터 통합 이동통신서비스 제공업자의 수익을 극대화시키는 최적 가격을 결정하는 모델을 제시한다. 특히 고려되는 음성서비스 및 데이터서비스의 가격방식은 현재 우리나라 이동통신서비스의 회선요금제와 패킷요금제를 각각 적용한다. 이 모델은 소비자들이 핸드오프도중 발생하는 통화단절에 매우 민감하게 반응한다는 가정하에, 기지국이 무선채널을 할당함에 있어서 핸드오프 트래픽만이 독점사용할 수 있는 가드채널을 할당하는 방안을 고려하며, 더불어 서비스제공업자가 통화단절율의 서비스 품질을 소비자군에게 보장하는 경우를 고려한다. 궁극적으로 이 모델은 단기적으로 가격전략 및 무선채널 할당정책에 의존하여 서비스 품질을 개선$.$보장할 수 있는 방안을 제시하며, 그 결과 시스템자원의 확충없이는 수익과 서비스 품질의 개선$.$보장간에 상충관계가 존재함을 보여준다.

• Journal of information and communication convergence engineering
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• 제8권5호
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• pp.513-518
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• 2010

This paper proposes a medium access control protocol for integrated voice and data services in slotted CDMA systems. The proposed protocol, which is named as RCSSMA (Reservation Code and Status Sensing Multiple Access), adopts a code reservation and status sensing schemes. RCSSMA protocol gives higher access priority to the voice traffic than data traffic for reducing the packet dropping probability. The voice terminal reserves an available spreading code to transmit voice packets during a talkspurt, whereas the data terminal transmits a packet over one of the available spreading codes that are not reserved by the voice terminals. In this protocol, the voice packets never contend with the data packets. Packet dropping probability and average data packet transmission delay are analyzed using a Markov chain model.

• 한국통신학회논문지
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• 제25권12B호
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• pp.2109-2119
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• 2000

In this paper, the Packet CDMA Reservation ALOHA protocol is proposed to support the multi-traffic services such as voice and videophone services with handoff calls, high-rate data and low-rate data services efficiently on the multi-rate transmission in uplink cellular systems. The frame structure, composed of the access slot and the transmission slot, and the proposed access permission probability based on the estimated number of contending users for each service are presented to reduce MAI. The assured priority to the voice and the videophone handoff calls is given through higher access permission probability. And through the proposed code assignment scheme, the voice service can be provided without the voice packet dropping probability in the CDMA/PRMA protocols. The code reservation is allowed to the voice and the videophone services. The low-rate data service uses the available codes during the silent periods of voice calls and the remaining codes in the codes assigned to the voice service to utilize codes efficiently. The high-rate data service uses the assigned codes to the high-rate data service and the remaining codes in the codes assigned to the videophone service. Using the Markov-chain subsystem model for each service including the handoff calls in uplink cellular systems, the steady-state performances are simulated and analyzed. After a round of tests for the examples, through the proposed code assignment scheme and the access permission probability, the Packet CDMA Reservation ALOHA protocol can guarantee the priority and the constant QoS for the handoff calls even at large number of contending users. Also, the data services are integrated efficiently on the multi-rate transmission.

• 한국멀티미디어학회논문지
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• 제6권7호
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• pp.1219-1230
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• 2003

본 논문에서는 음성, 스트림-데이터 및 패킷-데이터 트래픽이 혼합된 환경에서 전체 채널을 음성 우선 채널과 음성 비우선 채널로 구분하여 공유하는 CDMA 시스템을 마르코프 체인으로 해석한다. 실시간 전송이 요구되는 음성 서비스는 음성 우선 채널에 대해서는 선점 우선권(preemptive priority)을 가지고 사용하며, 음성 비우선 채널에 대해서는 스트림-데이터 서비스와 동등한 순위를 지니고 사용한다. 지연에 다소 민감하지 않은 스트림-데이터 서비스에 대해서는 버퍼를 사용한다. 또한, 전자우편 등과 같은 패킷-페이터 서비스는 타 서비스에 의해 사용되고 있지 않는 잔여 채널을 이용하여 최선의 시도를 통해 전송하도록 한다. 본 논문에서는 채널의 선점 우선권을 지니는 음성 서비스 및 버퍼가 적용된 스트림-데이터 서비스를 2-차원 마르코프 체인으로 모델링하고 분석하였으며, 잔여 용량(residual capacity)을 기초로 하여 패킷 데이터 트래픽에 대한 수학적 분석을 수행하였다.

• ETRI Journal
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• 제28권3호
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• pp.311-319
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• 2006

This paper presents a terminal-assisted frame-based packet reservation multiple access (TAF-PRMA) protocol, which optimizes random access control between heterogeneous traffic aiming at more efficient voice/data integrated services in dynamic reservation TDMA-based broadband access networks. In order to achieve a differentiated quality-of-service (QoS) guarantee for individual service plus maximal system resource utilization, TAF-PRMA independently controls the random access parameters such as the lengths of the access regions dedicated to respective service traffic and the corresponding permission probabilities, on a frame-by-frame basis. In addition, we have adopted a terminal-assisted random access mechanism where the voice terminal readjusts a global permission probability from the central controller in order to handle the 'fair access' issue resulting from distributed queuing problems inherent in the access network. Our extensive simulation results indicate that TAF-PRMA achieves significant improvements in terms of voice capacity, delay, and fairness over most of the existing medium access control (MAC) schemes for integrated services.