multicode cdma with V-BLAST architecture is an attractive scheme to achieve high data rate transmission in wireless communications. We propose an improved detection algorithm, order partial parallel interference cance...
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multicode cdma with V-BLAST architecture is an attractive scheme to achieve high data rate transmission in wireless communications. We propose an improved detection algorithm, order partial parallel interference cancellation with decision feedback (DF-OPPIC), to combat co-antenna interference and multiple access interference in the system. Compared with the conventional algorithms, DF-OPPIC has better performance on the frame error ratio in flat and multipath Rayleigh fading channel. Moreover, due to avoid calculating pseudo-inverse and optimal detection order in every time of iteration, DF-OPPIC has lower arithmetic complexity.
multicode cdma with V-BLAST architecture is an attractive scheme to achieve high data rate transmission. We propose an advanced detection scheme, order partial parallel interference cancellation with decision feedback...
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ISBN:
(纸本)0780375890
multicode cdma with V-BLAST architecture is an attractive scheme to achieve high data rate transmission. We propose an advanced detection scheme, order partial parallel interference cancellation with decision feedback (DF-OPPIC), to combat co-antenna interference and multiple access interference in the system. Compared with the original references, the scheme has better performance on the frame error ratio in flat Rayleigh fading channel and multipath Rayleigh fading channel. Moreover, due to avoid calculating pseudo-inverse and optimal detection order in every time of iteration, the scheme has lower arithmetic complexity.
The problem of transmitter adaptation in the form of adapting the spreading sequences and the transmission powers of different users for a multicode direct-sequence code division multiple access (DS-cdma) system is co...
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The problem of transmitter adaptation in the form of adapting the spreading sequences and the transmission powers of different users for a multicode direct-sequence code division multiple access (DS-cdma) system is considered, Particular attention is given to a distributed algorithm, which updates each pair of transmitter and receiver without information from other users. The transmitter adaptation problem and the algorithm are studied from the viewpoint of a single user, as well as the viewpoint of the whole system. The algorithm is shown to give either the optimal sequences or a choice of sequences that is close to the optimal one. Simulation results show that major improvement in performance can be obtained with the proposed transmission adaptation scheme. The effect of restricting the choice of sequences to polyphase sequences is also considered.
This paper investigates the application of multicode spread-spectrum code-division multiple-access (SS-cdma) techniques to three-dimensional (3-D) stereoscopic video transmission over wireless asynchronous transfer mo...
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This paper investigates the application of multicode spread-spectrum code-division multiple-access (SS-cdma) techniques to three-dimensional (3-D) stereoscopic video transmission over wireless asynchronous transfer mode (ATM) networks. Three-dimensional visual communications, made through the use of stereoscopic images, are able to achieve total display realism. Such services allow users to share the virtual reality (VR) world without any geographical restrictions. In order to create a 3-D system with two images (left and right) that should be transmitted over a bandlimited mobile channel simultaneously, a cost-effective Motion Picture Experts Group (MPEG)-based wavelet multiresolution coding with a joint motion and disparity compensation is developed to reduce a large amount of information contained in the images to meet the low-transmission rate limitation of mobile channels. However, the rapidly variable bit rate (VBR) characteristics of the MPEG-based 3-D videos seems a weakness to the transmission of such videos via a constant bit-rate (CBR) mobile channel. The ATM technique is especially well suited for VER MPEG-based 3-D video because of its ability to allocate bandwidth on demand to these services. However, since the mobile radio has a Limited channel capacity, the overall capacity of the traditional ATM-based SS-cdma system may not be sufficient to accommodate the MPEG-based 3-D video services requested by the multiple mobile users simultaneously. To tackle this difficulty, a multicode cdma technique is proposed to provide VER MPEG-based 3-D video services by varying the number of spreading codes assigned to the 3-D video to meet its dynamic throughput requirement. Powerful forward error correction (FEC) codes are necessary to protect the video data so that it can be successfully transmitted at an acceptable signal power level. Two separate FEC code schemes are applied to the header and payload of an ATM cell containing 3-D video data, respectively. The ATM
Future generations of wireless communication systems will be designed with the aim of making the best possible use of the limited radio spectrum in order to further increase throughput as well as user-capacity. In thi...
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Future generations of wireless communication systems will be designed with the aim of making the best possible use of the limited radio spectrum in order to further increase throughput as well as user-capacity. In this paper, the application of multicarrier cdma (code division multiple access) within mobile communication systems is discussed. An overview of the main types of multicarrier spread-spectrum systems is given. The multicarrier cdma system is described in detail, including its relationship with OFDM (orthogonal frequency division multiplexing), its general performance in comparison with direct sequence cdma and some specific implementation problems. The paper also presents some results comparing the performance of a selection of algorithms that can be used to isolate the individual signal of each user. Potential capacity increases achievable with adaptive loading in time and frequency slots is briefly demonstrated. By allocating users multiple codes, very high data rates can be achieved, and the paper gives a comparison of multicode, multicarrier cdma with OFDM-based wireless LAN systems.
The uplink access control problems for cellular code-division multiple-access (cdma) systems that service heterogeneous traffic with various types of quality-of-service (QoS) and use multicode cdma to support variable...
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The uplink access control problems for cellular code-division multiple-access (cdma) systems that service heterogeneous traffic with various types of quality-of-service (QoS) and use multicode cdma to support variable bit rates are addressed. Considering its distinct QoS requirements, class-I real-time traffic (e.g., voice and video) is differentiated from class-II non-real-time traffic (e.g., data). Connection-oriented transmission is achieved by assigning mobile-oriented code channels for class-I traffic, where each corresponding mobile needs to pass an admission test. Class-II traffic is transmitted in a best-effort manner through a transmission-rate request access scheme which utilizes the bandwidth left unused by class-I traffic. Whenever a mobile has class-II messages to transmit, the mobile requests code channels via a base station-oriented transmission-request code channel, then, according to the base station scheduling, the transmission is scheduled and permitted. Addressed are the admission test for class-I connections, transmission power allocation, and how to maximize the aggregate throughput for class-II traffic. The admission region of voice and video connections and the optimum target signal-to-interference ratio of class-II traffic are derived numerically. The performance of class-II traffic transmissions in terms of average delay is also evaluated and discussed.
In multi-code cdma, there is no self-interference among the subcodes of a single user. By taking advantage of this property, the authors propose a new scheduling scheme to improve throughput, and derive the system thr...
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In multi-code cdma, there is no self-interference among the subcodes of a single user. By taking advantage of this property, the authors propose a new scheduling scheme to improve throughput, and derive the system throughputs of two cases with the proposed scheme applied and not applied. Analysis results show that the proposed scheme considerably improves the system throughput.
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