Browsing by Author "Tseng, YC"

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A Borrow-and-Return model to reduce client waiting time for broadcasting-based VOD services
(2003-06-01)
Yang, MH
;
Chang, CH
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
One way to broadcast a popular video is to use multiple channels, each broadcasting a portion of the video periodically. Among the many schemes falling in this category, this paper focuses on several representative schemes (such as FB [15], [18], Pagoda [22], [24], and RFS [26]), which all share a FSFC property by repeatedly broadcasting the First Segment of the video on the First Channel. We propose a general Borrow-and-Return model that can be immediately applied to any scheme owning the FSFC property to reduce the viewer's waiting time without increasing the number of channels required. Given a group of videos, the basic idea is to lend the free time slots of videos without viewers to those videos with viewers to speedup the latter's transmission. By so doing, some bandwidth may be vacated by the borrowing videos to benefit others' transmission. Effectiveness of this model is analyzed by applying it to the FB scheme.
A fair scheduling algorithm with traffic classification for wireless networks
(2005-06-16)
Wang, YC
;
Ye, SR
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
Wireless channels are characterized by more serious bursty and location-dependent errors. Many packet scheduling algorithms have been proposed for wireless networks to guarantee fairness and delay bounds. However, most existing schemes do not consider the difference of traffic natures among packet flows. This will cause the delay-weight coupling problem. In particular, serious queuing delays may be incurred for real-time flows. To resolve this problem, we propose a traffic-dependent wireless fair queuing (TD-FQ) algorithm that takes traffic types of flows into consideration when scheduling packets. The proposed TD-FQ algorithm not only alleviates queuing delay of real-time flows, but also guarantees bounded delays and fairness for all flows. (c) 2004 Elsevier B.V. All rights reserved.
A fast video-on-demand broadcasting scheme for popular videos
(2004-06-01)
Sheu, JP
;
Wang, HL
;
Chang, CH
;
Tseng, YC
;
資訊工程學系
Broadcasting is a prospective approach to support near video-on-demand services with light communication overhead. By letting clients share channels, such approaches involve partitioning a video into segments and repeatedly broadcasting these segments in multiple channels. An early paper proposed a broadcasting scheme called RFS (recursive frequency splitting), which can significantly reduce clients' waiting time. While efficient, RFS suffers from a high computational complexity of O (n log n), where n is the number of segments of the video, which is typically very large. This paper proposes an efficient segmentation scheme, which can significantly reduce the computational overhead by slightly sacrificing the number of segments that can be arranged as compared to RFS.
A high throughput context-based adaptive arithmetic codec for JPEG2000
(2002)
Ong, KK
;
Chang, WH
;
Tseng, YC
;
Lee, YS
;
Lee, CY
In JPEG2000 image compression standard, context-based arithmetic coding is adopted for improving compression rate. Efficient and high throughput codec: design is strongly required for handling high-resolution images. We propose an efficient architecture for context-based adaptive arithmetic coding, which can achieve high throughput performance. Based on parallel leading zeros detection and bit-stuffing handling, symbol can be encoded and decoded within one cycle. Therefore, throughput rate can be increased as high as codec operating frequency. The modified encoding and decoding flows are compatible with JPEG2000 standard. For 0.35u 1P4M CMOS technology, encoding and decoding rate can run up to 200Msymbol/sec and 175Msymbol/sec respectively. They are only cost 6.8K and 9.8K gate count. These high throughput performances can meet high-resolution real time application requirement.
A high throughput low cost context-based adaptive arithmetic codec for multiple standards
(2002)
Ong, KK
;
Chang, WH
;
Tseng, YC
;
Lee, YS
;
Lee, CY
For next generation image compression standard, context-based arithmetic coding is adopted for improving compression rate. Efficient and high throughput codec design is strongly required for handling high-resolution images. We propose an efficient codec architecture for context-based adaptive arithmetic coding, which exhibits low cost, low latency, and high throughput rate. In addition, it can be programmed for supporting multiple standards such as JPEG, JPEG2000, JBIG, and JBIG2 standards. It is exploiting three-pipeline stages architecture. Based on parallel leading zeros detection and bit-stuffing handling, symbol can be encoded and decoded within one cycle. Therefore, throughput rate can be increased as high as codec operating clock rate. For 0.35u 1P4M CMOS technology, both encoding and decoding rate can run up to 185Msymbol/sec. The AC codec only costs 12K gate count and 860um x 860um layout area. These performances can meet high-resolution real time application requirement.
A jamming-based MAC protocol for wireless multihop ad hoc networks
(2003)
Ye, SR
;
Wang, YC
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
One critical issue in multihop ad hoc networks is the medium access control (MAC). The IEEE 802.11 MAC protocol is originally designed for fully connected, one-hop ad hoc networks but not for multihop ad hoc networks. In addition to the well known hidden-terminal problem, we found that IEEE 802.11 also suffers from an erroneous reservation problem which occurs when RTS-CTS exchange fails but the channel is incorrectly reserved. In this paper, we propose a jamming-based MAC (JMAC) protocol that is not only free from both hidden-terminal and the erroneous reservation problems but also allows more concurrent transmission/reception activities for stations within each other's transmission range. The idea behind the JMAC is to separate source stations' traffic from destination stations' traffic into different channels (i.e., dividing the shared medium into two channels), and explicitly signal the channel status by jamming the channels. Simulation results show that the JMAC can provide higher channel utilization when system is in high traffic load and the frame size is medium or large.
A jamming-based MAC protocol to improve the performance of wireless multihop ad-hoc networks
(2004-02-01)
Ye, SR
;
Wang, YC
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
One critical issue in multihop ad-hoc networks is the medium access control (MAC). The IEEE 802.11 MAC protocol is originally designed for fully connected, one-hop ad-hoc networks but not for multihop ad-hoc networks. In addition to the well known hidden-terminal problem, we found that IEEE 802.11 also suffers from an erroneous reservation problem which occurs when RTS-CTS exchange fails but the channel is incorrectly reserved. In this paper, we propose a jamming-based MAC (JMAC) protocol that is not only free from both the hidden-terminal and the erroneous reservation problems but also allows more concurrent transmission/receipt activities for stations within each other's transmission range. The idea behind the JMAC is to separate source stations' traffic from destination stations' traffic into different channels (i.e. dividing the shared medium into two channels), and explicitly signal the channel status by jamming the channels. Simulation results show that although the channel division incurs some cost, the advantages of being free from the erroneous reservation and the hidden-terminal problems, and the benefits of more concurrent transmissions will compensate the cost and provide higher channel utilization when data frame size is median or large. Copyright (C) 2004 John Wiley Sons, Ltd.
A multi-channel MAC protocol with power control for multi-hop mobile ad hoc networks
(2001)
Tseng, YC
;
Wu, SL
;
Lin, CY
;
Sheu, JP
;
資訊工程學系
In a mobile ad-hoc networks (MANET), one essential issue is Medium Access Control (MAC), which addresses how to utilize the radio spectrum efficiently and to resolve potential contention and collision among mobile hosts on rising the medium. Existing works have dedicated to using multiple channels [4, 6, 9. 10, 12, 18. 20] and power control [7, 13. 21] to improve the performance of MANET: III this paper.,ve investigate the possibility of bringing the concepts of power control a,ld multi-channel medium access together in the MAC design problem in a MANET: Existing protocols only address one of these issues independent): The proposed protocol is characterized by the following features: (i) it follows an "on-demand" style to assign, channels to mobile hosts. (ii) the number of channels required is independent of the network topology and degree, (iii) it flexibly adapts to host mobility: (iv) no form of clock synchronization is required, and(v) power control is used to exploit frequency reuse. Power control may also extend battery life and reduce signal interference. both of,which are important in wireless communication Through simulations, we demonstrate the advantage of our new protocol.
A multi-channel MAC protocol with power control for multi-hop mobile ad hoc networks
(2002)
Wu, SL
;
Tseng, YC
;
Lin, CY
;
Sheu, JP
;
資訊工程學系
In a mobile ad hoc network (MANET), one essential issue is Medium Access Control (MAC), which addresses how to utilize the radio spectrum efficiently and to resolve potential contention and collision among mobile hosts on using the medium. Existing works have been dedicated to using multiple channels and power control to improve the performance of MANET. In this paper, we investigate the possibility of bringing the concepts of power control and multi-channel medium access together in the MAC design problem in a MANET. Existing protocols only address one of these issues independently. The proposed protocol is characterized by the following features: (i) it follows an 'on-demand' style to assign channels to mobile hosts, (ii) the number of channels required is independent of the network topology and degree, (iii) it flexibly adapts to host mobility, (iv) no form of clock synchronization is required and (v) power control is used to exploit frequency reuse. Power control may also extend battery life and reduce signal interference, both of which are important in wireless communication. Through simulations, we demonstrate the advantage of our new protocol.
A multi-path QoS routing protocol in a wireless mobile ad hoc network
(2002)
Liao, WH
;
Wang, SL
;
Sheu, JP
;
Tseng, YC
;
資訊工程學系
A mobile ad hoc network (MANET) is one composed of a set of mobile hosts capable of communicating with each other without the assistance of base stations. This paper considers the QoS (quality-of-service) routing problem in a MANET, which is important for many real-time multimedia applications. We propose an on-demand protocol for searching for a multi-path QoS route from a source host to a destination host in a MANET, where a multi-path is a network with a source and a sink satisfying certain bandwidth requirement. Existing works all try to find a uni-path to the destination. The basic idea is to distribute a number of tickets from the source, which can be further partitioned into subtickets to search for a satisfactory multi-path. Through simulations, we justify that the value of our multi-path protocol is in its flexibility: (i) when the network bandwidth is very limited, it can offer a higher success rate to find a satisfactory QoS route than those protocols which try to find a uni-path, and (ii) when the network bandwidth is sufficient, it can perform almost the same as those protocols which try to find a uni-path (in both routing overhead and success rate).
A multi-path QoS routing protocol in a wireless mobile ad hoc network
(2001)
Liao, WH
;
Tseng, YC
;
Wang, SL
;
Sheu, JP
;
資訊工程學系
A mobile ad hoc network (MANET) is one consisting of a set of mobile hosts capable of communicating with each other without the assistance of base stations, This paper considers the QoS (quality-of-service) routing problem in a MANET. We propose an on-demand protocol for searching for a multi-path QoS route from a source host to a destination host in a MANET, where a multi-path is a network with a source and a sink satisfying certain bandwidth requirement. Existing works all try to find a uni-path to the destination. The basic idea is to distribute a number of tickets from the source, which can be further partitioned into sub-tickets to search for a satisfactory multi-path. Through simulations, we justify that the value of our multi-path protocol is on its flexibility: (i) when the network bandwidth is very limited, it can offer a higher success rate to find a satisfactory QoS route than those protocols which try to find a uni-path, and (ii) when the network bandwidth is sufficient, it can perform almost the same as those protocols which try to find a uni-path (in both routing overhead and success rate).
A new BlueRing scatternet topology for Bluetooth with its formation, routing, and maintenance protocols
(2003-06-01)
Lin, TY
;
Tseng, YC
;
Chang, KM
;
資訊工程學系
;
Department of Computer Science
The basic networking unit in Bluetooth is piconet, and a larger-area Bluetooth network can be formed by multiple piconets, called scatternet. However, the structure of scatternets is not defined in the Bluetooth specification and remains as an open issue at the designers' choice. It is desirable to have simple yet efficient scatternet topologies with good supports of routing protocols, considering that Bluetooths are to be used for personal area networks with design goals of simplicity and compactness. In the literature, although many routing protocols have been proposed for mobile ad hoc networks, directly applying them poses a problem due to Bluetooth's special baseband and MAC-layer features. In this work, we propose an attractive scatternet topology called BlueRing, which connects piconets as a ring interleaved by bridges between piconets, and address its formation, routing, and topology-maintenance protocols. The BlueRing architecture enjoys the following fine features. First, routing on BlueRing is stateless in the sense that no routing information needs to be kept by any host once the ring is formed. This would be favorable for environments such as Smart Homes where computing capability is limited. Second, the architecture is scalable to median-size scatternets easily (e.g. around 50 similar to 70 Bluetooth units). In comparison, most star- or treelike scatternet topologies can easily form a communication bottleneck at the root of the tree as the network enlarges. Third, maintaining a BlueRing is an easy job even as some Bluetooth units join or leave the network. To tolerate single-point failure, we propose a protocol-level remedy mechanism. To tolerate multipoint failure, we propose a recovery mechanism to reconnect the BlueRing. Graceful failure is tolerable as long as no two or more critical points fail at the same time. As far as we know, the fault-tolerant issue has not been properly addressed by existing scatternet protocols yet. In addition, we also evaluate the ideal network throughput at different BlueRing sizes and configurations by mathematical analysis. Simulation results are presented, which demonstrate that BlueRing outperforms other scatternet structures with higher network throughput and moderate packet delay. Copyright (C) 2003 John Wiley Sons, Ltd.
A novel interference-resolving algorithm to support asymmetric services in TDD-CDMA systems with directional antennas
(2002)
Wang, LC
;
Huang, SY
;
Tseng, YC
;
電信工程研究所
;
Institute of Communications Engineering
This paper presents a new cross-slot interference-resolving algorithm for supporting unbalance traffic between downlink and uplink in TDD-CDMA systems. To avoid cross-slot interference between downlink and uplink, traditional algorithms typically require a global control on the transmission direction in each time slot among all cells. Obviously, this requirement significantly limits one of the key advantages in the TDD system -- enabling different rate asymmetry. We observe that the tri-sector cellular architecture possesses additional orthogonality inherently due to the directivity of directional antenna, which can provide an additional degree of freedom in allocating radio resource (i.e., time slots). Thus we propose a new distributed slot allocation algorithm based on the tri-sector cellular architecture. The advantage of the proposed algorithm is to enable a TDD-CDMA system to provide asymmetric services with different rates of asymmetry in all cells, thereby having more flexibility in handling uniform traffic patterns.
A power and area efficient multi-mode FEC processor
(2004)
Tseng, YC
;
Lin, CC
;
Chang, HC
;
Lee, CY
;
電子工程學系及電子研究所
Forward Error Correction (FEC) is a key component in communication system which mostly contains scrambler, Reed-Solomon coding, interleaving, and trellis coding. For the performance and complexity issues, design parameters are different in various applications. In this paper, a multi-mode FEC processor is presented to meet different system requirements with a power and area efficient architecture. The proposed processor is fully compliant to ITU-T J.83 cable modem system including the reconfigurable Reed-Solomon decoder and memory-based universal convolutional interleaver. With 0.18um 1P6M CMOS technology, the simulation result shows the FEC decoder can work over 100MHz while costs 54.5K gate counts and two 376x8 bits embedded duel-port SRAM. The average power consumption in most critical mode is about 34.2mW at 100MHz. While running at 7MHz that meets symbol rate of cable modem, the power dissipation is 2.32mW.
A priority MAC protocol to support real-time traffic in ad hoc networks
(2004-01-01)
Sheu, JP
;
Liu, CH
;
Wu, SL
;
Tseng, YC
;
資訊工程學系
Carrier sense multiple access and its variants have been widely used in mobile ad hoc networks. However, most existing access mechanisms cannot guarantee quality for real-time traffic. This paper presents a distributed medium access control protocol that provides multiple priority levels for stations to compete for the wireless channel. One common channel is assumed to be shared by all stations. Stations are assumed to be able to hear each other (i.e., the network is fully connected). The channel is accessed by stations according to their priorities, and for stations with the same priority, they send frames in a round robin manner. The channel access procedure is divided into three stages: priorities classification period, ID initialization period, and transmission period. Simulation results indicate that our protocol provides high channel utilization and bounded delays for real-time frames.
A probabilistic signal-strength-based evaluation methodology for sensor network deployment
(2005)
Kuo, SP
;
Tseng, YC
;
Wu, FJ
;
Lin, CY
;
資訊工程學系
The deployment of senor networks have attracted a lot of attention recently. In essence this issue is concerned with how well a sensing field is monitored by sensors to achieve a particular coverage. In this paper, we propose a signal-strength-based approach to evaluate how well a sensing field is covered/monitored. We first formulate object tracking by a single sensor as a Gaussian-error model. Then we establish an error model on location estimation given that the location of an object is known. This leads to a model to evaluate a sensor network with given locations of sensors. We then apply the result to several applications, such as adding more sensor nodes for error reduction and scheduling power modes (awake or sleep) of sensors, and demonstrate our simulation results.
A secure data hiding scheme for binary images
(2002-08-01)
Tseng, YC
;
Chen, YY
;
Pan, HK
;
資訊工程學系
;
Department of Computer Science
This letter presents a novel steganography scheme capable of concealing a piece of critical information in a host message which is a binary image (e.g., a facsimile). A binary matrix and a weight matrix are used as secret keys to protect the hidden information. Given a host image of size m x n, the proposed scheme can conceal as many as [log(2) (mn + 1)] bits of data in the image by changing, at most, two bits in the host image. This scheme can provide a higher security, embed more information, and maintain a higher quality of the host image than available schemes.
A Stop-or-Move Mobility model for PCS networks and its location-tracking strategies
(2003-07-21)
Tseng, YC
;
Chen, LW
;
Yang, MH
;
Wu, JJ
;
資訊工程學系
This paper considers the location-tracking problem in PCS networks. Solutions to this problem in fact highly depend on the mobility patterns of mobile subscribers [ACM DIAL-M (1999) 72]. In the literature, many works have assumed a simple random walk model, where mobile subscribers always stay in a roaming state and can move in any direction with equal probability. In this paper, we propose a new Stop-or-Move Mobility (SMM) model, which is characterized by the following features: 'transition between stop and move', 'infrequent transition', 'memory of roaming direction', and 'oblivious in different moves'. Based on this mobility model, a static and an adaptive location-tracking Scheme are developed. The schemes only need to keep very little information for each user. Analyses and simulations are provided, which show that the proposed schemes are quite prospective. (C) 2003 Elsevier Science B,V. All rights reserved.
A two-tier heterogeneous mobile ad hoc network architecture and its load-balance routing problem
(2004-08-01)
Huang, CF
;
Lee, HW
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
The mobile ad hoc network (MANET) has attracted a lot of interest recently. However, most of the existing works have assumed a stand-alone MANET. In this paper, we propose a two-tier, heterogeneous MANET architecture which can support Internet access. The low tier of the network consists of a set of mobile hosts each equipped with a IEEE 802.11 wireless LAN card. In order to connect to the Internet and handle the network partitioning problem, we propose that the high tier is comprised of a subset of the mobile hosts, called gateways, which can access to cellular/infrastructure networks. The high tier is heterogeneous in the sense that the network interfaces in the gateway hosts could be IEEE 802.11 cards, PHS handsets, or GPRS handsets characterized by different bandwidths and latencies. Observing that the gateways could become the bottlenecks of the two-tier network, we propose a set of solutions, namely boundary-moving, host-partitioning, and probabilistic solutions, to solve the load-balance routing issue. Implementation issues/concerns of these schemes are discussed. Simulation results are presented to compare these load-balance routing schemes.
A two-tier heterogeneous mobile ad hoc network architecture and its load-balance routing problem
(2003)
Huang, CF
;
Lee, HW
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
The mobile ad hoc network- (MANET) has attracted a lot of interest recently. However, most of the existing works have assumed a stand-alone MANET. In this paper, we propose a two-tier, heterogeneous MANET architecture which can support Internet access. The low tier of the network consists of a set of mobile hosts each equipped with a IEEE 802.11 wireless LAN card. In order to connect to the Internet and handle the network partitioning problem, we propose that the high tier is comprised of a subset of the mobile hosts, called gateways, which can access to cellular/infrastructure networks. The high tier is heterogeneous in the sense that the network interfaces in the gateway hosts could be IEEE 802.11 cards, PHS handsets, or GPRS handsets characterized by different bandwidths and latencies. Observing that the gateways could become the bottlenecks of the two-tier network, we propose a set of solutions, namely boundary-moving and host-partitioning solutions, to solve the load-balance routing issue. Implementation issues/concerns of these schemes are discussed. Simulation results are presented to compare these load-balance routing schemes.