• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.9
• /
• pp.50-57
• /
• 2011

Conventional bus system architectures are composed of several components such as master, arbiter, decoder and slave modules. The arbiter plays a role in bus arbitration according to the selected arbitration method, since several masters cannot use the bus concurrently. Typical priority strategies used in high performance arbiters include static priority, round robin, TDMA and lottery. Typical arbitration algorithms always consider the bus priority primarily, while the bus utilization is always ignored. In this paper, we propose an arbitration method using bus utilization for the operating block of each master. We verify the performance compared with the other arbitration methods through the TLM(Transaction Level Model). Based on the performance verification, the conventional fixed priority and round-robin arbitration methods cannot set the bus utilization. Whereas, in the case of the conventional TDMA and lottery arbitration methods, more than 100,000 cycles of bus utilization can be set by the user, exhibiting differences of actual bus utilization up to 50% and 70%, respectively. On the other hand, we confirm that for the proposed arbitration method, the matched bus utilization set by the user was above 99% using approximately 1,000 cycles.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.1A
• /
• pp.59-66
• /
• 2008

This paper presents a spectrum sharing and allocation problem in multiple network operators(NOs). Most of previous works as to dynamic spectrum allocation(DSA) schemes have presented the DSA gain achieved by utilizing the time or regional variations in traffic demand between multi-network operators(NOs). In this paper, we introduce the functionalities required for the entities related with the spectrum sharing and allocation and propose a spectrum allocation algorithm while considering the long-term priority(or fairness) between NOs, the prioritybetween multiple class services, and the urgent bandwidth request. It was shown that the proposed algorithm with priorities between multiple class services could sustain better satisfaction ratio(SR) than the fixed allocation schemes or one without priority under different traffic patterns. Therefore, we conclude that the proposed DSA with priorities between multiple class services and network operators could provide the fairness between service classes of network operators and effective negotiation procedure for urgent bandwidth request by users.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.11
• /
• pp.2433-2438
• /
• 2011

Bus system consists of several masters, slaves, arbiter and decoder in a bus. Master means the processor that performs data command like CPU, DMA, DSP and slave means the memory that responds the data command like SRAM, SDRAM and register. Furthermore, as multiple masters can't use a bus concurrently, arbiter plays an role in bus arbitration. In compliance with the selection of arbitration method, bus system performance can be changed definitely. Fixed priority and round-robin are used in general arbitration method and TDMA and Lottery bus methods are proposed currently as the improved arbitration schemes. In this study, we proposed the score arbitration method and synthesized it using Hynix 0.18um technology, after design of RTL. Also we analyze the performance compared with general arbitration methods through simulation.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.46 no.2
• /
• pp.38-44
• /
• 2009

Bus system consists of several masters, slaves, arbiter and decoder in a bus. Master means the processor that performs data command like CPU, DMA, DSP and slave means the memory that responds the data command like SRAM, SDRAM and register. Furthermore, as multiple masters can't use a bus concurrently, arbiter plays an role in bus arbitration. In compliance with the selection of arbitration method bus system performance can be charged definitely. Fixed priority and round-robin are used in general arbitration method and TDMA and Lottery bus methods are proposed currently as the improved arbitration schemes. In this stuff, we proposed the score arbitration method and composed TLM algorithm. Also we analyze the performance compared with general arbitration methods through simulation. In the future, bus arbitration policy will be developed with the basis of the score arbitration method and improve the performance of bus system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.6
• /
• pp.1065-1071
• /
• 2009

Satellite application services can be divided into realtime services like voice communications and non-real time services like traditional data communications. To support both types of services on the same On-Board Switching(OBS), a scheduler which depends on their service classes is required. A fixed priority scheduling policy has a starvation problem. In this paper we propose a scheduling scheme based on premium and age. Premium is a fixed value which is given to a certain class of services. Age is another parameter of the scheduling policy and it will be increased by one for every scheduling cycle. The scheme we propose chooses a packet which has the largest sum of its age and premium. Simulation results indicate that the proposed approach shows better performance in both average cell delay and std-dev of cell delay for the lower class of service. There is no staying in infinite starvation state.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.45 no.5
• /
• pp.1-7
• /
• 2008

The general bus architecture consists of masters, slaves, arbiter, decoder and so on in shared bus. Specially, as several masters do not concurrently receive the right of bus usage, the arbiter plays an important role in arbitrating between shared bus and masters. Fixed priority, round-robin, TDMA and Lottery methods are developed in general arbitration policies, which lead the efficiency of bus usage in shared bus. On the other hand, the bus architecture can be modified to maximize the system performance. In the paper, we propose the flying master bus architecture that supports the parallel bus communication and analyze its merits and demerits following various arbitration policies that are mentioned above, compared with normal shared bus. From the results of performance verification using TLM(Transaction Level Model), we find that more than 40% of the data communication performance improves, regardless of arbitration policies. As the flying master bus architecture advances its studies and applies various SoCs, it becomes the leading candidate of the high performance bus architecture.

• Journal of KIISE:Computer Systems and Theory
• /
• v.32 no.4
• /
• pp.148-159
• /
• 2005

We propose a technique for finding the worst case response time (WCRT) of a DMA request that is needed in the schedulability analysis of a whole real-time system. The technique consists of three steps. In the first step, we find the worst case bus usage pattern of each CPU task. Then in the second step, we combine the worst case bus usage pattern of CPU tasks to construct the worst case bus usage pattern of the CPU. This second step considers not only the bus requests made by CPU tasks individually but also those due to preemptions among the CPU tasks. finally, in the third step, we use the worst case bus usage pattern of the CPU to derive the WCRT of DMA requests assuming the fixed-priority bus arbitration protocol. Experimental results show that overestimation of the DMA response time by the proposed technique is within $20\%$ for most DMA request sizes and that the percentage overestimation decreases as the DMA request size increases.

• Journal of Institute of Control, Robotics and Systems
• /
• v.10 no.11
• /
• pp.1058-1064
• /
• 2004

This paper presents a distributed precedence queue mechanism to resolve unexpected transmission delay of a lower priority transaction in a CAN based system, which keeps a fixed priority in data transaction. The mechanism is implemented in the upper sub-layer of the data link layer(DLL), which is fully compatible with the original medium access control layer protocol of CAN. Thus the mechanism can be implemented dynamically while the data transactions are going on without any hardware modification. The CAN protocol was originally developed to be used in the automotive industry, and it was recently applied for a broader class of automated factories. Even though CAN is able to satisfy most of real-time requirements found in automated environments, it is not to enforce either a fair subdivision of the network bandwidth among the stations or a satisfactory distribution of the access delays in message transmission. The proposed solution provides a superset of the CAN logical link layer control, which can coexist with the older CAN applications. Through the real experiments, effectiveness of the proposed mechanism is verified.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.761-766
• /
• 2005

This paper presents a dynamic precedence queue mechanism to resolve unexpected transmission delay of a lower priority transaction in a CAN based system which keeps a fixed priority in data transactions. The mechanism is implemented in the upper sub-layer of the data link layer (DLL), which is fully compatible with the original medium access control layer protocol of CAN. Thus the mechanism can be implemented dynamically while the data transactions are going on without any hardware modification. The CAN protocol was originally developed to be used in the automotive industry and it was recently applied for a broader class of automated factories. Even though CAN is able to satisfy most of real-time requirements found in automated environments, it is not to enforce either a fair subdivision of the network bandwidth among the stations or a satisfactory distribution of the access delays in message transmissions. The proposed solution provides a superset of the CAN logical link layer control, which can coexist with the older CAN applications. Through the real experiments, effectiveness of the proposed mechanism is verified.

• Journal of Korean Institute of Industrial Engineers
• /
• v.35 no.2
• /
• pp.150-159
• /
• 2009

The heterogeneous fleet vehicle routing problem(HVRP) is a variant of the classical vehicle routing problem in which customers are served by a heterogeneous fleet of vehicles with various capacities, fixed costs and variable costs. We propose a new conceptual HVRPCR(HVRP with customer restriction) model including additional customer restrictions in HVRP. In this paper, we develop hybrid particle swarm optimization(HPSO) algorithm with 2-opt and node exchange technique for HVRP. The solution representation is a n-dimensional particle for HVRP with N customers. The decoding method for this representation starts with the transformation of particle into a priority list of customer to enter route and limit of vehicle to serve each customer. The vehicle routes are then constructed based on the customer priority list and limit of vehicle to serve. The proposed algorithm is tested using 8 benchmark problems and it consistently produces high-quality solutions, including new best solutions. The numerical results show that the proposed algorithm is robust and efficient.