The MultiCarrier Code Division Multiple Access (MC-CDMA) scheme is promising for relieving capacity limit problems of Direct Sequence (DS-) CDMA systems due to serious InterChip Interference (ICI) and MultiUser Interf...The MultiCarrier Code Division Multiple Access (MC-CDMA) scheme is promising for relieving capacity limit problems of Direct Sequence (DS-) CDMA systems due to serious InterChip Interference (ICI) and MultiUser Interference (MUI) in high-data-rate wireless communication systems. In this paper, the Uniform Linear Array (ULA) is applied to the base station of macrocellular MC-CDMA systems in a frequency-selective fading channel environment. A joint space-frequency multiuser symbol sequence detector is developed for all active users within one macrocell without space-frequency channel estimation. Simultaneously, Directions-Of-Arrivals (DOAs) of all active users can also be estimated. By dividing the ULA into two identical overlapping subarrays, a specific auxiliary matrix is constructed, which includes both symbol sequence and DOA information of all active users. Then, based on the subspace method, performing the eigen decomposition on such auxiliary matrix, the closed-form solution of symbol sequences and DOAs for all active users can be obtained. In comparison with schemes based on channel estimation, our algorithm need not explicitly estimate the space-frequency channel for each active user,so it has lower computation complexity. Extensive computer simulations demonstrate the overall performance of this novel scheme.展开更多
This paper proposes a closed-form joint space-time channel and Direction Or Arrival (DOA) blind estimation algorithm for space-time coded Multi-Carrier Code Division Multiple Access (MC-CDMA) systems equipped with a U...This paper proposes a closed-form joint space-time channel and Direction Or Arrival (DOA) blind estimation algorithm for space-time coded Multi-Carrier Code Division Multiple Access (MC-CDMA) systems equipped with a Uniform Linear Array (ULA) at the base station in frequency-selective fading environments. The algorithm uses an ESPRIT-like method to separate multiple co-channel users with different impinging DOAs. As a result, the DOAs for multiple users are obtained. In particular, a set of signal subspaces, every one of which is spanned by the space-time vector channels of an individual user, are also obtained. From these signal subspaces, the space-time channels of multiple users are estimated using the subspace method. Computer simulations illustrate both the validity and the overall performance of the proposed scheme.展开更多
In this paper, a Direction Of Arrival (DOA) estimation algorithm is proposed for multiuser signals through uplink asynchronous multipath Code Division Multiple Access (CDMA) channels. The algorithm is based directly o...In this paper, a Direction Of Arrival (DOA) estimation algorithm is proposed for multiuser signals through uplink asynchronous multipath Code Division Multiple Access (CDMA) channels. The algorithm is based directly on the correlation matrices of matched filter bank outputs of desired user’s multipath signals and it does not require that the elements of base station antenna array outnumber the multipath signals, which is necessary for the conventional sub-space based direction-finding algorithm. Simulation results show that the proposed algorithm estimates the DOA of multipath signals effectively and acceptably. The proposed algorithm has the prominent advantages of low complexity, simpleness and practicality, which make it much more suitable for practical application.展开更多
This paper proposes an improved Direction Of Arrival(DOA) estimation algorithm for asynchronous multipath Code Division Multiple Access(CDMA) system. The algorithm is based on the correlation matrices of outputs of de...This paper proposes an improved Direction Of Arrival(DOA) estimation algorithm for asynchronous multipath Code Division Multiple Access(CDMA) system. The algorithm is based on the correlation matrices of outputs of decorrelator, which is a Multi-User Detection(MUD) approach, one of the key techniques for CDMA system. Through decorrelating processing, the desired user's mulipath signals can be resolved and all the other resolved multipath signal interference is eliminated. So the proposed algorithm is expected to perform much better than algorithm such as that based directly on the Matched Filter(MF) bank outputs. Simulation results confirm this. While the improved algorithm performs better and better as Signal-to-Noise Ratio(SNR) increases, the performance of algorithm based directly on the MF bank outputs can not be improved.展开更多
In this paper, a simple method is presented for multi-user space-time channel estimation in Time Division-Synchronized Code Division Multiple Access (TD-SCDMA) systems. The method is based on a spe- cific midamble ass...In this paper, a simple method is presented for multi-user space-time channel estimation in Time Division-Synchronized Code Division Multiple Access (TD-SCDMA) systems. The method is based on a spe- cific midamble assignment strategy, which results in a cyclic Toeplitz midamble-matrix in the linear equation of the received data vectors. A Fast Fourier Transform (FFT)-based algorithm is used to obtain the estimate of the uplink multi-user space-time channels. Furthermore, the estimated space-time channel is applied to the identification of multi-paths for each user, and Direction Of Arrival (DOA) estimation for each path is carried out by using the extracted spatial signature vector. Aside from the simplicity in computation, the proposed di- rection of arrival estimation method can effectively resolve multi-paths regardless of the correlation and angle separations of the multi-paths.展开更多
基金Partially supported by the National Natural Science Foundation(No.69872029)and the Research Fund for Doctoral Program of Higher Education(No.19990690808)of China
文摘The MultiCarrier Code Division Multiple Access (MC-CDMA) scheme is promising for relieving capacity limit problems of Direct Sequence (DS-) CDMA systems due to serious InterChip Interference (ICI) and MultiUser Interference (MUI) in high-data-rate wireless communication systems. In this paper, the Uniform Linear Array (ULA) is applied to the base station of macrocellular MC-CDMA systems in a frequency-selective fading channel environment. A joint space-frequency multiuser symbol sequence detector is developed for all active users within one macrocell without space-frequency channel estimation. Simultaneously, Directions-Of-Arrivals (DOAs) of all active users can also be estimated. By dividing the ULA into two identical overlapping subarrays, a specific auxiliary matrix is constructed, which includes both symbol sequence and DOA information of all active users. Then, based on the subspace method, performing the eigen decomposition on such auxiliary matrix, the closed-form solution of symbol sequences and DOAs for all active users can be obtained. In comparison with schemes based on channel estimation, our algorithm need not explicitly estimate the space-frequency channel for each active user,so it has lower computation complexity. Extensive computer simulations demonstrate the overall performance of this novel scheme.
基金Partially supported by the National Natural Science Foundation of China (No.60272071)the Research Fund for Doctoral Program of Higher Education of China (No.20020698024 & 20030698027).
文摘This paper proposes a closed-form joint space-time channel and Direction Or Arrival (DOA) blind estimation algorithm for space-time coded Multi-Carrier Code Division Multiple Access (MC-CDMA) systems equipped with a Uniform Linear Array (ULA) at the base station in frequency-selective fading environments. The algorithm uses an ESPRIT-like method to separate multiple co-channel users with different impinging DOAs. As a result, the DOAs for multiple users are obtained. In particular, a set of signal subspaces, every one of which is spanned by the space-time vector channels of an individual user, are also obtained. From these signal subspaces, the space-time channels of multiple users are estimated using the subspace method. Computer simulations illustrate both the validity and the overall performance of the proposed scheme.
基金The Social Development Projects of Jiangsu Science and Technology Department(No.BE2018704)the Technological Innovation Projects of Ministry of Public Security of China(No.20170001)。
基金Supported by the National Natural Science Foundation of China(No.60372014).
文摘In this paper, a Direction Of Arrival (DOA) estimation algorithm is proposed for multiuser signals through uplink asynchronous multipath Code Division Multiple Access (CDMA) channels. The algorithm is based directly on the correlation matrices of matched filter bank outputs of desired user’s multipath signals and it does not require that the elements of base station antenna array outnumber the multipath signals, which is necessary for the conventional sub-space based direction-finding algorithm. Simulation results show that the proposed algorithm estimates the DOA of multipath signals effectively and acceptably. The proposed algorithm has the prominent advantages of low complexity, simpleness and practicality, which make it much more suitable for practical application.
基金Supported by the National Natural Science Foundation of China(No. 60372014)
文摘This paper proposes an improved Direction Of Arrival(DOA) estimation algorithm for asynchronous multipath Code Division Multiple Access(CDMA) system. The algorithm is based on the correlation matrices of outputs of decorrelator, which is a Multi-User Detection(MUD) approach, one of the key techniques for CDMA system. Through decorrelating processing, the desired user's mulipath signals can be resolved and all the other resolved multipath signal interference is eliminated. So the proposed algorithm is expected to perform much better than algorithm such as that based directly on the Matched Filter(MF) bank outputs. Simulation results confirm this. While the improved algorithm performs better and better as Signal-to-Noise Ratio(SNR) increases, the performance of algorithm based directly on the MF bank outputs can not be improved.
基金Supported by the Natural Foundation of Hubei Province, China (No.2005ABA224).
文摘In this paper, a simple method is presented for multi-user space-time channel estimation in Time Division-Synchronized Code Division Multiple Access (TD-SCDMA) systems. The method is based on a spe- cific midamble assignment strategy, which results in a cyclic Toeplitz midamble-matrix in the linear equation of the received data vectors. A Fast Fourier Transform (FFT)-based algorithm is used to obtain the estimate of the uplink multi-user space-time channels. Furthermore, the estimated space-time channel is applied to the identification of multi-paths for each user, and Direction Of Arrival (DOA) estimation for each path is carried out by using the extracted spatial signature vector. Aside from the simplicity in computation, the proposed di- rection of arrival estimation method can effectively resolve multi-paths regardless of the correlation and angle separations of the multi-paths.
