• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1434-1440
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• 2008

Performance of TCP/IP is studied on the wireless network using flow control and congestion control mechanism based on transmission rate. We discuss the elimination or the reduction of various phenomena of burst by flow controlling on transmission rate and verify that there are TCP ACK compression promblems on the queue by burst reaction while executing transmission rate controlled channels. Analyzing periodic burst reaction on the queue of source IP, the maximum value of queue is expected, which represents the applible expectation of throughput reduce and shows the improvement of performance by the reduce of throughput due to hi-directional traffic.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.2
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• pp.33-40
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• 2008

Streaming video has become a popular form of transferring media over the wired/wireless network. TCP-friendly rate control (TFRC) is used as a streaming media transport protocol. Using the TCP congestion response function and current network conditions, TFRC adjusts its sending rate to yield the maximum TCP-friendly throughput. Since TFRC was designed for applications that would prefer to maintain a slowly-changing sending rate, it is less responsive to changes in handover between wireless heterogeneous networks such as 3G network, WLAN, and so on. This paper shows a new TFRC method for vertical handover over wireless heterogeneous network. The proposed TFRC method has features of low quality interruption and fast rate adaptation to a new target network. The simulation results show that the proposed one provides better QoS and throughput support than the traditional TFRC scheme during vertical handover.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.9
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• pp.734-740
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• 2012

In this paper, we propose a method for throughput improvement in multirate multihop wireless networks with intra-session network coding. A multirate transmission supports several rates so that it has a tradeoff between transmission rate and transmission range, therefore multirate can cope with the performance degradation. We present the rate selection method with intra-session network coding in multirate nodes. The effective transmission rate is calculated by using intra-session network coding, and then its maximum effective transmission rate is selected. Concurrent transmission set is determined by selected transmission rate and then the linear programming is formulated for throughput calculation in multihop wireless networks. We evaluate the performance by using MATLAB and lp_solve programs in two topologies. It is shown that the throughput of the proposed method is improved.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.104-113
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• 2013

A high-throughput Quasi-Cyclic Low-Density Parity-Check (QC-LDPC) decoder architecture is proposed for 60GHz multi-gigabit wireless personal area network (WPAN) applications. Two novel techniques which can apply to our selected QC-LDPC code are proposed, including a four block-parallel layered decoding technique and fixed wire network. Two-stage pipelining and four block-parallel layered decoding techniques are used to improve the clock speed and decoding throughput. Also, the fixed wire network is proposed to simplify the switch network. A 672-bit, rate-1/2 QC-LDPC decoder architecture has been designed and implemented using 90-nm CMOS standard cell technology. Synthesis results show that the proposed QC-LDPC decoder requires a 794K gate and can operate at 290 MHz to achieve a data throughput of 3.9 Gbps with a maximum of 12 iterations, which meet the requirement of 60 GHz WPAN applications.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.92-101
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• 2012

In this paper, we propose a distributed transmit power control algorithm for optimal end-to-end throughput in wireless multihop networks. Considering a solidarity property of link rates consisting of a multihop link and the fact that the multihop end-to-end throughput is determined by the minimum link rate, the proposed scheme controls the transmit power to make all link rates be equal and so maximizes the end-to-end throughput of multihop link. In addition, in the proposed scheme the transmit node calculates its transmit power autonomously in a distributed manner just through the information sharing with its neighbor nodes and so decreases the information sharing overhead. Simulation results show that the proposed scheme achieves significant improvements in terms of end-to-end throughput and power consumption compared with the conventional maximum equal power allocation scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.28-33
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• 2007

In spite of the large interest in the 802.15.4 standard, no realistic experimental research of its behaviour exists to date except a few works by simulations and analytical modeling. In this paper, we have established realistic environment of IEEE 802.15.4 network and analyze its behaviour under various conditions as like 1) maximum throughput of 802.15.4 MAC, 2) MAC fairness. and 3) throughput and m rate under co-existence of 802.11 Wi-Fi wireless networks.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.282-291
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• 2001

In this paper, an efficient VLSI architecture of Shape Adaptive Discrete Cosine Transform(SADCT) based on systolic array is proposed. Since transform size in SADCT is varied according to the shape of object in each block, it are dropped that both usability of processing elements(PE´s) and throughput rate in time-recursive SADCT structure. To overcome these disadvantages, it is proposed that the architecture based on a systolic way structure which doesn´t need memory. In the proposed architecture, throughput rate is improved by consecutive processing of one-dimensional SADCT without memory and PE´s in the first column are connected to that in the last one for improvement of usability of PE. And input data are put into each column of PE in parallel according to the maximum data number in each rearranged block. The proposed architecture is described by VHDL. Also, its function is evaluated by MentorTM. Even though the hardware complexity is somewhat increased, the throughput rate is improved about twofold.

• Journal of Electrical Engineering and information Science
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• v.1 no.1
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• pp.23-28
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• 1996

In this series of two papers, adaptive code rate change schemes in DS-SSMA systems are proposed. In the proposed schemes the error correcting code rate is changed according to the channel states. Two channel states having significant effects on the bit error probability are considered: one is the effective number of users considered in Part 1, and the other is the fading environment considered in Part 2. These channel states are estimated based on retransmission requests. The criterion for the change of the code rate is to maximize the throughput under given error bound. Simulation results show that we can transmit maximum amount of information if we change the code rate based on the channel states.

• ETRI Journal
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• v.19 no.4
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• pp.326-343
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• 1997

In this paper, we propose an ATM switch with the rate more than gigabits per second to cope with future broadband service environments. The basic idea is to separate the connection control flow from the data information flow inside the switch. The proposed switch has a dual-plane switch matrix with the synchronous control algorithm. The queuing behaviors of the proposed switch are shown by the discrete-time queuing analysis. Numerical analyses are taken both in the non-blocking crossbar switch and the banyan switch with internal blocking. Results show that a proposed dual-plane $16{\times}16$ switch would have the acceptable performance with maximum throughput of about 95 percent.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12B
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• pp.1665-1676
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• 2001

The effect of spreading gain control on the throughput of a CDMA slotted ALOHA system is considered. Mobile users transmit packets over a shared channel, and the packets transmitted in the same time slot over the shared channel act as simultaneous access interference (SAI). When using spread-spectrum signal, a CDMA slotted ALOHA channel achieves high probability of capture due to the property of high title resolution, and the bit rate of user information is determined by spreading gain. When the SAI level gets larger, the high value of spreading gain enhances the packet throughput by increasing the probability of a successful packet transmission, while it degrades the of the effective throughput by reducing the user information bits carried within a packer. To solve the problem, we investigated the effect of the capture probability and the SAI level on these system throughputs, and evaluated the throughput performance of the system for each spreading gain control scheme. The results showed that the maximum effective throughput could be achieved with an unified method despite the variation of the SAI level by deriving an optimal value of the spreading gain according to 171e system states.