• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.11A
• /
• pp.1106-1112
• /
• 2007

As a demand for high speed uplink packet services increases, the WCDMA enhanced uplink, also known as high speed uplink packet access (HSUPA), has been specified in release 6 by 3GPP. This HSUPA will provide various types of multimedia services, such as real-time video streaming, gaming, VoIP, and FTP. Generally, the performance of HSUPA is dominated by scheduling policy. Therefore, it is required to design a scheduling algorithm considering the traffic characteristics to provide QoS guaranteed services in various traffic environments. In this paper, we propose a scheduling algorithm considering the traffic characteristics to guarantee QoS in a mixed traffic environment. Finally, the performance of the proposed scheduling algorithm is evaluated in terms of average packet delay, packet delay jitter, and system throughput using a system level simulator.

• The KIPS Transactions:PartC
• /
• v.16C no.5
• /
• pp.661-668
• /
• 2009

The Extended real-time Polling Service (ErtPS) is proposed tosupport QoS of VoIP service with silence suppression which generates variable size data packets in IEEE 802.16e systems. If the silence is suppressed, VoIP should support Comfort Noise Generation (CNG) which generates comfort noise for receiver's auditory sense to notify the status of connection to the user. CNG mode in silent-period generates a data with lower bit rate at long packet transmission intervals in comparison with talk-spurt. Therefore, if the ErtPS, which is designed to support service flows that generate data packets on a periodic basis, is applied to silent-period, resources of the uplink are used inefficiently. In this paper, we proposed the Improved ErtPS algorithm for efficient resource utilization of the silent-period in VoIP traffic supporting CNG. In the proposed algorithm, the base station allocates bandwidth depending on the status of voice at the appropriate interval by havingthe user inform the changes of voice status. The Improved ErtPS utilizes the Cannel Quality Information Channel (CQICH) which is an uplink subchannel for delivering quality information of channel to the base station on a periodic basis in 802.16e systems. We evaluated the performance of proposed algorithm using OPNET simulator. We validated that proposed algorithm improves the bandwidth utilization of the uplink and packet transmission latency

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.11A
• /
• pp.1630-1641
• /
• 2000

본 논문은 셀룰러 시스템 상향 링크에서 음성데이터 및 실시간 영상데이터로 구성된 화상전화서비스, 고속 및 저속 데이터베이스의 다중 전송률 멀티미디어 서비스를 통합 지원할수 있는 CDMA R-ALOHA 프로토콜을 제안하였다. 제안된 프로토콜은 액세스슬롯과 전송슬롯으로 구분된 프레임의 구조를 이용한 코드할당 방식으로 전송슬롯에서의 간섭을 줄였다. 그리고, 각 서비스의 트래픽 특성에 따른 전송코드 예약과 화상전화서비스 사용자의 핸드오프호를 고려하여 분석된 각 서비스 부시스템의 Markov-chain 모델을 이용한 각 서비스의 채널 경쟁 사용자수 추정을 기반으로 서비스별 액세스 허용확률을 제안하여, 액세스슬롯에서의 패킷 충돌을 감소시키고 핸드오프호의 우선권을 보장할 수있다. 또한 화상전화서비스의 영상데이터 전송정보를 이용한 코드 예약방식을 제안하여, 음성 트래픽을 패킷의 손실이 없이 지원하였고 고속 및 저속 데이터베이스를 통해 채널 이용효율을 극대화하였다.

• Proceedings of the KAIS Fall Conference
• /
• 2010.05a
• /
• pp.99-102
• /
• 2010

TDMA/TDD을 기반으로 동작하는 HiperLAN/2의 MAC 프로토콜에서 무선채널은 중앙제어방식으로 운영되는 AP(Access Point)에 의해서 할당된다. 상향링크로 데이터 전송이 필요한 이동단말은 RCH 채널을 통하여 AP에게 무선자원을 요청한다. 각 MAC 프레임마다 RCH 수를 동적으로 변경하는 것이 중요한데, RCH 수가 많이 할당되면 무선자원의 낭비를 초래하며, RCH 수가 적게 할당되면 이동단말간의 충돌이 증가하고 AP에 접속하는 시간도 길어진다. 따라서 무선자원을 효율적으로 사용하기 위해 RCH 수는 트래픽에 따라 적절하게 할당되어야 한다. 본 논문에서는 HiperLAN/2에서의 성능향상을 위해 패킷의 충돌수와 성공수를 고려하여 RCH 수를 동적으로 변화시키는 방법을 제안하였다. 제안한 방법의 효율성을 입증하기 위해 시뮬레이션을 수행하였으며, 처리율과 접속지연 관점에서 분석하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.1A
• /
• pp.16-24
• /
• 2010

High Speed Uplink Packet Access(HSUPA) is a WCDMA Release 6 technology which corresponds to High Speed Downlink Packet Access(HSDPA). Node B Supports fast scheduling, Hybrid ARQ(HARQ), short Transmission Time Interval(TTI) for high rate uplink packet data. It is very important to detect Iub congestion to improve end user's Quality of Service(QoS). This paper proposes Node B Congestion Detection(BCD) mechanism and suggests to use the hybrid of Transport Network Layer(TNL) congestion detection and BCD. It is shown that HSUPA user throughput performance can be improved by the proposed method even with small Iub bandwidth.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.4
• /
• pp.787-793
• /
• 2015

In order to support reliable medium access control (MAC) layer multicast services in Broadband Wireless Access (BWA) networks, we here propose spreading codes (Cumulative ACK (CA) code and ARQ Feedback Request (AFR) code) based reliable multicast feedback scheme. The status indications based on the automatic repeat request (ARQ) mechanism are needed in some multicast services. In accordance with various wireless channel environments, we demonstrate the performance excellency of our proposed scheme with respect to required uplink resources compared with the original feedback scheme based on unicast ARQ feedback messages. In addition, we analyze packet error rate (PER) against the various wireless channel environments.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.5B
• /
• pp.449-455
• /
• 2006

Due to advance in multimedia applications and integrated Internet services, the optical access networks have been actively studied. In particular, Ethernet passive optical network (EPON) has received much attention due to high bandwidth provision with low cost. In EPON system, the data transmission is carried out in two directions: downstream (from OLT to ONU) and upstream (from ONU to OLT). The downstream data is broadcasted to every ONUs, while the upstream data is point-to-point transmitted between each ONU and OLT, where the uplink is shared by all ONUs in the form of TDMA. The bandwidth allocation algorithm is required to efficiently manage the bandwidth on the uplink. The limited algorithm was proposed to enhance the capability of dynamic bandwidth allocation. In this paper, we propose the adaptive limited algorithm to enhance the shortcomings of limited algorithm. The adaptive limited algorithm enhances the dynamics on bandwidth allocation, and at the same time controls the fairness on packet delay. Through the computer simulations, it is shown that the adaptive limited algorithm achieves high dynamic on bandwidth allocation, maintains a good fairness on packet delay between ONUs, and keeps the fairness on the bandwidth on the demand basis.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.42 no.3
• /
• pp.562-565
• /
• 2017

In this letter, we consider a 7-step transmission procedure of a large number of machine nodes when they simultaneously request random access to transmit uplink data. We model the radio resource utilization of LTE systems, and analyze the overloaded resources. From the simulation results, we show that the resource of PDCCH becomes significantly overloaded as the number of machine nodes increases in a cell. To alleviate the overload of PDCCH, we allocate radio resource of PDSCH to PDCCH. The result shows that the resource utilization of PDCCH is improved.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.5
• /
• pp.1173-1183
• /
• 1998

This paper proposes an SS-PRMA protocol for the integrated voice and data services in the packet radio networks. In this protocol, the uplink logical channels are provided by combining the time slots and the spreding codes. SS-PRMA protocol contains some features of existing protocols such as PRMA, slotted ALOHA, and CDMA. In the proposed protocol, the voice terminals use a reservation mechanism, and the dta terminals use a slotted ALOHA scheme. The analysis and the simulation results show that most of the performances for the voice traffic can be achieved by employing a few distinct spreading codes and the data traffic throughput is closely related to the number of spreading code channels. Also it shows that the data traffic performance can be significantly improved by applying an FEC scheme to the data link layer.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.12
• /
• pp.32-40
• /
• 2015

Code division multiple access (CDMA) is one of the promising medium access control scheme for underwater acoustic sensor networks due to its beneficial features such as robustness against frequency-selective fading and high frequency-reuse efficiency. In this paper, we design a closed-loop power control scheme for the underwater CDMA, to adapt time-varying acoustic channel. In the proposed scheme, sink node sends to sensor nodes the associated path loss which is acquired by uplink-channel analysis based on received packets from the sensor nodes. Then, sensor nodes adjust their transmission power in an adaptive manner to time-varying underwater acoustic channel, according to the informations sent by the sink node.