• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.96-103
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• 2000

The voice traffic is one of the most important real-time objects in WATM(Wireless Asynchronous Transfer Mode) networks. In this paper, we propose a new MAC(Medium Access'Control) protocol for the efficienttransmission of voice traffic over WATM networks in the multimedia environment and compare the performanceto existing similar protocols. The new protocol separates the reservation slot period for voice and that for data toguarantee some level of QoS(Quality of Service) in voice traffic. This is denoted by a slot assignment functiondepending on the frame size. According to the characteristics of voice traffic which is repeatedly in silent states,the protocol allocates voice reservation request slots dynamically with respect to the number of silent(off state)voice sources and also sends the first block of talkspurt restarted after silent period with a reservation requestslot to reduce the access delay.The simulation results show that the proposed protocol has better performance than Slotted Aloha in bandwidthefficiency, and can serve a certain level of QoS by the given slot assignment function even when the number ofvoice terminals varies dynamically. This means we can observe that the new MAC protocol is much better thanthe NC-PRMA(None Collision-Packet Reservation Multiple Access) protocol.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.677-682
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• 2004

In the present paper routing and wavelength assignment (RWA) in optical WDM networks is considered. Previous techniques based on the combination of integer linear programming and graph coloring are complex and require extensive use of heuristics. Such methods are mostly slow and sometimes impossible to get results due to infeasibility. An alternative approach applied to RWA employs on the greedy algorithm for obtaining the maximum edge disjoint paths. Even though this approach is fast, it produces a solution for any connection request, which is very far from the optimal utilization of wavelengths. We propose a novel algorithm, which is based on the maximum flow technique to obtain the maximum quantity of edge, disjoint paths. Here we compare the offered method with previous maximum edge disjoint paths algorithms ap plied to the RWA.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.1
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• pp.108-121
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• 2008

Dispatching rule for parallel machines with multi product is proposed in this paper, In current market,customer's request for higher quality is increasing, In accordance with such demand, manufacturers are focusingon improving the quality of the products. Such shift in production objective is risky. The possibility ofneglecting another important factor in customer satisfaction increases, namely due dates. From the aspect ofimproving quality, frequency of product assignment to limited number of high performance machines willincrease. This will lead to increased waiting time which can incur delays, In the case of due date orientedproduct dispatch, Products are assigned to machines without consideration for quality. Overall deterioration ofproduct quality is inevitable, In addition, Poor products will undergo rework process which can increase delays.The objective of this research is dispatching products to minimize due date delays while improving overallquality. Quality index is introduced to provide means of standardizing product quality. The index is used toassure predetermined quality level while minimizing product delays when dispatching products. Qualitystandardization method and dispatching algorithm is presented. And performance evaluation is performed withcomparison to various dispatching methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1282-1289
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• 2000

In this paper we propose a Fractional Channel Reservation (FCS) scheme to satisfy a desired handoof dropping probability and to reduce the blocking probability of new calls using mobility characteristics and incoming handoff rate in mobile communication networks. When the ratio of the handoff call arrival rate is less then the ratio of the new call arrival rete, the proposed scheme is capable of determining the number of the guard channels which can guarantee the Quality of Service(QoS) in terms of the request handoff dropping probability and allocating dynamically the wireless channels the new calls according to the rest of the guard channels to reduce the new call blocking probability. Also we perform mathematical analysis and simulation to evaluate the performance of proposed scheme and compare to conventional guard channel scheme in terms of dropping probability blocking probability and the utilization efficiency of wireless channels.

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

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.8
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• pp.1549-1560
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• 2009

In the TDMA PON system, the DBA is essential for ONUs to send data efficiently to the upstream. In this paper, we implement a DBA processor for the G-PON OLT with downstream and upstream rate, 2.5 and 1.25 Gbps, respectively, The processor collects bandwidth request messages from ONUs at every cycle time and allocates properly bandwidth to each Alloc-ID with considering priority and fairness for traffics. In the proposed DBA algorithm, one cycle time consists of multiple G-PON frames ($m{\times}125{\mu}s$) for high link efficiency. In particular, the link efficiency is higher because the algorithm adopts a method that an additional overhead is eliminated when an allocated bandwidth is laid between two G-PON frames for an ONU. This enables that the processor flexibly allocates the bandwidth from zero to the maximum link capacity for an ONU. The proposed DBA processor is implemented with the FPGA and shows bandwidth allocating processes for ONUs with logic analyzer.

• Journal of KIISE:Information Networking
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• v.31 no.2
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• pp.196-206
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• 2004

In the Next Generation Internet(NGI) backbone network, a Dense Wavelength Division Multiplexing (DWDM) technology has been more and more highlighted to cover the increasing subscribers and bandwidth requirement. For such a DWDM network, Routine and Wavelength Assignment (RWA) is the essential problem to establish the optimal path and assign a wavelength efficiently to the selected path in resource utilization. However, the existing RWA algorithms do not consider the congestion in the network so that the performance of then is so limited. To solve this problem, in this paper, we introduce a new RWA algorithm, called Multi Wavelength-Minimum Interference path Routing (MW-MIPR) that establishes a routing path to minimize the interference for many potential future connection setup request. And then, we also propose a wavelength-routed QoS routing scheme based on differentiated QoS classes with applying MW-MIPR algorithm. Simulation results are also given to prove the efficiency of the proposed algorithms.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.5
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• pp.431-441
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• 1997

In this paper, a performance evaluation method for the Trunked Land Mobile Radio System, so called TRS(Trunked Radio System), is presented. The proposed evaluation method employs LCD(Lost Call Delayed) system model and Erlang-C distribution. In this system, queues are used to hold call requests that are initally blocked. When a user attempts a call and a channel is not immediately available, the call request may be delayed until a channel becomes available. For evaluating system performance, therefore, the probability that any caller is delayed in the queue for a waiting time greater than t seconds is derived and simulated by using such parameters as total number of available channels, traffic load and average duration of a call. Furthermore, the performance of the message and the transmission trunked channel assignment strategies is compared. The performance simulation results show that transmission trunking is shown to be more efficient than message trunking.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.149-160
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• 2008

As individual users have to provide more information than the minimum for using information communication service, the invasion of privacy of Individual users is increasing. That is why client/server based personal information security platform technologies are being developed such as P3P, EPAL and XACML. By the way enterprises and organizations using primarily role based access control can not use these technologies. because those technologies apply access control policies to individual subjects. In this paper, we suggest an expression language for privacy enhancing role-based access control policy. Suggested privacy enhancing role-based access control policy language model is a variation of XACML which uses matching method and condition, and separately contains elements of role, purpose, and obligation. We suggest policy language model for permission assignment in this paper, shows not only privacy policy scenario with policy document instance, but also request context and response context for helping understanding.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.10
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• pp.1-9
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• 2001

The MAC (Medium Access Control) protocol is needed for the OLT(Optical Line Termination) to allocate bandwidth to ONUs(Optical Network Units) and ONTs(Optical Network Terminations) dynamically in the ATM PON(Passive Optical Network). With the protocol, the OLT gathers ONUs' informations and provides grants efficiently to each ONU. Two important functions of the MAC protocol is the grant request procedure and the grant distribution algrithm. The latter has the greatest arithmetic portion in the TC(Transmission Convergence) module, occupies a relatively large portion of the overall chip area, has often been the limiting factor in terms of speed, and should be designed to guarantee the quality of service for various traffics. In this paper, we implement the MAC with the FPGA which can allocate grants dynamically according to the queue length information and the number of active ONUs and distribute grants uniformly to minimize the cell delay variation for each ONU. The structure of the MAC scheduler for the dynamic bandwidth assignment has a programmable look-up table. Also, it has a simple structure, the less chip area, and the lower delay time.