Browsing by Author "Lin, YW"

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A dynamic scaling FFT processor for DVB-T applications
(2004-11-01)
Lin, YW
;
Liu, HY
;
Lee, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents an 8192-point FFT processor for DVB-T systems, in which a three-step radix-8 FFT algorithm, a new dynamic scaling approach, and a novel matrix prefetch buffer 1 are exploited. About 64 K bit memory space can be saved in the 8 K point FFT by the proposed dynamic scaling approach. Moreover, with data scheduling and pre-fetched buffering, single-port memory can be adopted without degrading throughput rate. A test chip for 8 K mode DVB-T system has been designed and fabricated using 0.18-mum single-poly six-metal CMOS process with core area of 4.84 mm(2). Power dissipation is about 25.2 mW at 20 MHz.
A new dynamic scaling FFT processor
(2004)
Lin, YW
;
Lee, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new FFT processor with radix-8 algorithm and novel matrix buffer is presented in this paper. About 64 K bit memory can be saved in 8 K-point FFT by new dynamic scaling approach. Moreover, with data scheduling and prefetched buffering, single-port memory can be adopted in our FFT processor. A test chip for 8 K mode DVB-T system has been designed and fabricated using 0.18 mu m CMOS process with core area of 4.84mm(2) and consumes only 25.2 mW at 20 MHz.
Accelerating network security services with fast packet classification
(2004-10-15)
Shieh, S
;
Lee, FY
;
Lin, YW
;
資訊工程學系
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Department of Computer Science
To protect a network, secure network systems such as intrusion detection system (IDS) and firewall are often installed to control or monitor network traffic. These systems often incur substantial delay for analyzing network packets. The delay can be reduced with fast packet classification, which can effectively classify network traffic, and consequently accelerate the analysis of network packets. In the last few years, many researchers devoted to providing fast packet classification methods for multidimensional classifier. However, these methods either suffer from poor performance and huge storage requirement, or are lack of dimension scalability. In this paper, we propose a packet classification method based on tuple space search, and use the multidimensional binary search tree (Kd-tree) to improve search performance. The proposed scheme requires only O(d log W) search time and controlled storage requirement, where d is the number of dimensions, and W is the utmost bit length for specifying prefixes in a classification rule. It features fast packet classification, and supports dynamic update which is a basic requirement of many secure network services, such as IDS and firewall. (C) 2004 Elsevier B.V. All rights reserved.
An efficient approach for hierarchical submodule extraction
(2004)
Lin, YW
;
Jou, JY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The growth of modem IC design complexity leads the consistency check and design verification during every level in design flow to be an important and challenged issue. In this paper, we propose an efficient approach to rebuild the hierarchical level from low level circuits. Our approach is based on the structure equivalent expansion algorithm to find repeated submodules in every circuit level to reconstruct circuit hierarchy. Without any addition library information, our approach is quite efficient in both time and space complexities by using only flatten netlists. The experiments on many real circuits containing combinational, sequential, and memory circuits show that our approach can rebuild most circuit hierarchical levels and also reduce the verification effort of the circuits.
Cross-layer goodput analysis for rate adaptive IEEE 802.11 a WLAN in the generalized Nakagami fading channel
(2004)
Wang, LC
;
Lin, YW
;
Liu, WC
;
交大名義發表
;
National Chiao Tung University
This paper aims to evaluate the goodput performance of the IEEE 802.11a wireless local area network (WLAN) from both the media access control (MAC) layer and physical (PHY) layer perspectives. From the physical layer perspective, we analyze the packet error rate performance of the orthogonal frequency division multiplexing (OFDM) based WLANs under the generalized Nakagami fading channel. According to the Chernoff bound analysis in the Nakagand fading channel, we derive the approximate packet error rate for the IEEE 802.11a WLAN with different data rates and fading parameters. Furthermore, we propose an efficient channel driven rate adaptation (CDRA) scheme. Through a PHY/MAC cross-layer analysis, we demonstrate that the goodput of the CDRA scheme indeed approaches to that of the optimal dynamic programming based rate adaptation method, while avoiding the complex calculations in selecting transmission parameters as the optimal method.
Improvement of high-speed oxide-confined vertical-cavity surface-emitting lasers
(2004-04-01)
Yu, HC
;
Chang, SJ
;
Su, YK
;
Sung, CP
;
Yang, HP
High-speed vertical-cavity surface-emitting lasers that could be modulated up to 10 Giga-bit-per-second (Gbps) were accomplished by using additional proton implantation to reduce the parasitic capacitance. The eye diagram of the implanted device shows a noticeable improvement when compared with those devices without implantation. In contrast to previous reports, moreover, the output power-current-voltage (L-I-V) characteristics of the fabricated devices ill this study show excellent consistency between before and after implantation. The high-temperature lifetime of devices fabricated with a similar process has already exceeded 8100 h up to the present day.
Physical layer effects on the MAC goodput performance for the rate adaptive IEEE 802.11 a/g WLAN
(2004)
Liu, WC
;
Wang, LC
;
Lin, YW
;
交大名義發表
;
National Chiao Tung University
According to the IEEE 802.11n, the next generation wireless local area networks (WLAN) aim to support data rates at least 100 Mbps, as measured at the medium access control (MAC) layer. Thus, it is important to develop a cross-layer analytical model to evaluate the MAC layer goodput performance with consideration of the physical layer effects. This paper suggests such an analytical model to calculate the MAC layer goodput for the IEEE 802.11a WLAN in the Nakagami fading channel, while incorporating the effects of channel estimation, delay spread and signal detection scheme in the physical layer. Furthermore, we develop a simple and efficient channel-driven rate adaptation (CDRA) scheme to dynamically adjust the transmission parameters to maximize the MAC layer goodput. From out numerical results, we find that some physical (PHY) modes in the IEEE 802.11a are unnecessary. We also find that as rms delay spread increases, the goodput in the MAC layer can be improved due to frequency diversity. For the case of rms delay spread changing from 50 to 200 nsec with 15 dB E-b/N-0, the goodput is improved from 12 Mbps to 15 Mbps.