Browsing by Author "Tsai, TC"

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A beamspace-time blind RAKE receiver for sectored CDMA systems
(2001-04-01)
Lee, TS
;
Tsai, TC
;
Chen, CH
;
電信工程研究所
;
友訊交大聯合研發中心
A beamspace-time (BT) RAKE receiver is proposed for multiple access interference (MAT) suppression and multipath diversity reception in sectored wireless CDMA communications. The scheme involves three stages. First, a set of adaptive beamformers encompassing a prescribed angular sector is constructed on an antenna array, each providing effective suppression of out-of-sector MAI and reception of in-sector signal. Second, a set of adaptive correlators is attached to each beam to combat in-sector MAI. Finally, the beamspace correlator output data are combined to capture the signal multipaths coherently. The above three-stage operation is performed in a blind mode in that no training signal is needed. The only information required is the signature, timing and a rough estimate of the angle of arrival (AOA) of the desired signal.
A beamspace-time interference canceling CDMA receiver for sectored communications in a multipath environment
(2001-07-01)
Lee, TS
;
Tsai, TC
;
電信工程研究所
;
友訊交大聯合研發中心
;
Institute of Communications Engineering
A beamspace-time (BT) receiver is proposed for interference suppression and multipath diversity reception in sectored wireless code division multiple access communications. The scheme involves two stages, First, a set of adaptive space-time diversity processors, in the form of beamformer-correlator pairs, is constructed which provides effective suppression of unwanted interference and reception of signals from a prescribed spare-time region, Second, the output data obtained by these processors are maximum ratio combined to capture the signal multipath components coherently. The proposed BT receiver is blind in that no training signal is required. The only information required is the signature sequence, timing and a rough estimate of the angle of arrival of the signal for selecting the sector of interest.
A beamspace-time rake receiver for sectored CDMA systems
(2000)
Lee, TS
;
Tsai, TC
;
電信工程研究所
;
Institute of Communications Engineering
A beamspace-time (BT) RAKE receiver is proposed for multiple access interference (MAI) suppression and multipath diversity reception in sectored wireless CDMA communications. The scheme involves two stages. First, a set of diversity beamformers is constructed and then combined for each finger which provides effective reception of in-sector signals and suppression of out-of-sector MAI. Second, an adaptive correlator is attached to each combined beam to combat in-sector MAI and collect signal multipaths in a coherent manner The proposed BT RAKE receiver is blind in that no training signal is required. The only information required is the signature sequence, timing and a rough estimate of the angle of arrival (AOA) of the signal.
A new two-layer quantum-dot large-neighborhood cellular nonlinear network (QLN-CNN) using quantum-dot cellular automata
(2002)
Tsai, TC
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Sun, M
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Lin, LJ
;
Huang, KH
;
Cheng, CH
A novel structure of QLN-CNN is proposed. The new structure of the QLN-CNN contains two layers of QCA array and introduces concepts of the A cloning templates, the B cloning templates, and the thresholds. The gene-decoding concept of CNNs is also used in this structure. Thus it operates more like real CNNs. In this paper, three CNN operations are proven to be achieved by this new structure through MATLAB simulations.
A partially adaptive CDMA interference canceller for multipath channels
(2000)
Lee, TS
;
Tsai, TC
;
電信工程研究所
;
Institute of Communications Engineering
An adaptive receiver with enhanced interference rejection is proposed for CDMA communications over multipath channels. The design of the receiver involves a two-stage procedure. First, an adaptive correlator bank is constructed in the form of generalized sidelobe canceller (GSC) to suppress strong interference. To reduce complexity, the partially adaptive implementation is incorporated in the design of GSC blocking matrix. Next, a maximum ratio combining of the correlator outputs is performed to constructively collect the multipath energy. Since strong MAI has been removed, channel estimation can be done accurately, leading to improved performance compared to the conventional RAKE receiver.
Multihop wireless IEEE 802.11 LANs: A prototype implementation
(2000-12-01)
Lin, YD
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Hsu, YC
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Oyang, KW
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Tsai, TC
;
Yang, DS
In this paper; we present a prototype for a new architecture, MCN (Multihop Cellular Network) implemented over a wireless LAN platform. MCN preserves the virtue of traditional single-hop cellular networks where the service infrastructure is constructed bl; many BSs (Ease Stations) but it also adds the flexibility of ad hoc networks where wireless transfer through mobile stations in multiple hops is allowed. MCN can reduce the number of required BSs or improve the throughput performance, In the prototype of MCN, a bridging protocol, BRIEF (Base-driven Multihop Bridging Protocol) runs between mobile stations and access points to enable multihop routing and roaming. Demonstration show that MCN is a feasible architecture for wireless LANs.
QoS routing in multihop packet radio environment
(1998)
Hsu, YC
;
Tsai, TC
;
Lin, YD
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資訊工程學系
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Department of Computer Science
In this paper, we present a method to compute the path bandwidth for the DSDV-based routing algorithm The addressed network does not necessarily have a cellular structure and could have no fired infrastructure. This network can be either stand-alone, or connected to the wired network. Each mobile station has to relay packets for others, thus achieving multihop routing. To calculate the available bandwidth of a path in this environment, it is incorrect to simply compute the minimum bandwidth of the links along the path. There are two crucial steps in the path bandwidth computation process of this multihop environment: (I) intersecting the sets of common free slots of two adjacent links, and (2) dividing the intersection for the adjacent links to share. We present two bandwidth computation rules including the Half rule and the Floating rule. Numerical results are given to evaluate the performance of applying these rules to the DSDV-based QoS routing algorithm.