Sat, 19 Jul 2008 03:07:39 BST CiteULike: dcastro's multi http://www.citeulike.org/user/dcastro/tag/multi CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/2763869 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 10. (2005), pp. 3082-3089.</i><br /><br />The use of direct RF sampling has been explored as a means of designing multifrequency RF front ends. Such front ends will be useful to multifrequency RF applications such as global navigation satellite system receivers that use global positioning system (GPS) L1, L2, and L5 signals and Galileo signals. The design of a practical multifrequency direct RF sampling front end is dependent on having an analog-to-digital converter whose input bandwidth accommodates the highest carrier frequency and whose maximum sampling frequency is more than twice the cumulative bandwidth about the multiple carrier signals. The principle of direct RF sampling is used to alias all frequency bands of interest onto portions of the Nyquist bandwidth that do not overlap. This paper presents a new algorithm that finds the minimum sampling frequency that avoids overlap. This design approach requires a multifrequency bandpass filter for the frequency bands of interest. A prototype front end has been designed, built, and tested. It receives a GPS coarse/acquisition code at the L1 frequency and GPS antispoofing precision code at both L1 and L2. Dual-frequency signals with received carrier-to-noise ratios in excess of 52 dB-Hz have been acquired and tracked using this system. Design and practical implementation of multifrequency RF front ends using direct RF sampling ML Psiaki SP Powell Hee Jung PM Kintner doi:10.1109/TMTT.2005.855127 Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 10. (2005), pp. 3082-3089. 2008-05-07T06:08:30-00:00 2005 Microwave Theory and Techniques, IEEE Transactions on 53 10 3082 3089 design frequency front-end galileo gnss gps multi rf sampling http://www.citeulike.org/user/dcastro/article/2421597 <i>Vehicular Technology, IEEE Transactions on, Vol. 39, No. 1. (1990), pp. 56-67.</i><br /><br />The problem of meeting the proliferating demands for mobile telephony within the confinement of the limited radio spectrum allocated to these services is addressed. A multiple-beam adaptive base-station antenna is proposed as a major system component in an attempt to solve this problem. The approach is demonstrated by employing an antenna array capable of resolving the angular distribution of the mobile users as seen at the base-station site, and then using this information to direct beams toward either lone mobiles, or groupings of mobiles, for both transmit and receive modes of operation. The energy associated with each mobile is thus confined within the addressed volume, greatly reducing the amount of cochannel interference experienced from and by neighboring cochannel cells. To ascertain the benefits of such an antenna, the conventional and proposed antenna systems are modeled in a typical mobile radio environment. For a given performance criterion, the theoretical results indicate that a significant increase in the spectral efficiency, or capacity, of the network is obtainable with the proposed antenna The performance enhancement of multibeam adaptive base-station antennas for cellular land mobile radio systems SC Swales MA Beach DJ Edwards JP Mcgeehan doi:10.1109/25.54956 Vehicular Technology, IEEE Transactions on, Vol. 39, No. 1. (1990), pp. 56-67. 2008-02-24T13:46:17-00:00 1990 Vehicular Technology, IEEE Transactions on 39 1 56 67 adaptive antenna beam beamformer cellular mobile multi radio wireless http://www.citeulike.org/user/dcastro/article/2421339 <i>Information Theory, IEEE Transactions on, Vol. 49, No. 10. (2003), pp. 2636-2647.</i><br /><br />The capacity of multiple-input multiple-output (MIMO) wireless channels is limited by both the spatial fading correlation and rank deficiency of the channel. While spatial fading correlation reduces the diversity gains, rank deficiency due to double scattering or keyhole effects decreases the spatial multiplexing gains of multiple-antenna channels. In this paper, taking into account realistic propagation environments in the presence of spatial fading correlation, double scattering, and keyhole effects, we analyze the ergodic (or mean) MIMO capacity for an arbitrary finite number of transmit and receive antennas. We assume that the channel is unknown at the transmitter and perfectly known at the receiver so that equal power is allocated to each of the transmit antennas. Using some statistical properties of complex random matrices such as Gaussian matrices, Wishart (1928) matrices, and quadratic forms in the Gaussian matrix, we present a closed-form expression for the ergodic capacity of independent Rayleigh-fading MIMO channels and a tight upper bound for spatially correlated/double scattering MIMO channels. We also derive a closed-form capacity formula for keyhole MIMO channels. This analytic formula explicitly shows that the use of multiple antennas in keyhole channels only offers the diversity advantage, but provides no spatial multiplexing gains. Numerical results demonstrate the accuracy of our analytical expressions and the tightness of upper bounds. Capacity of multiple-antenna fading channels: spatial fading correlation, double scattering, and keyhole Hyundong Shin Jae Lee doi:10.1109/TIT.2003.817439 Information Theory, IEEE Transactions on, Vol. 49, No. 10. (2003), pp. 2636-2647. 2008-02-24T12:58:16-00:00 2003 Information Theory, IEEE Transactions on 49 10 2636 2647 antenna capacity channel correlation fading multi spatial http://www.citeulike.org/user/dcastro/article/2397695 <i>Information Theory, 2000. Proceedings. IEEE International Symposium on (2000), 495.</i><br /><br />An exact error probability analysis clearly demonstrates that adaptive antenna arrays are unable to fully exploit the implicit diversity effect of Rayleigh fading channels. Instead, a class of array receivers that yields close-to-optimal performance is proposed On multi-antenna receiver principles for correlated Rayleigh fading channels A Hansson TM Aulin doi:10.1109/ISIT.2000.866793 Information Theory, 2000. Proceedings. IEEE International Symposium on (2000), 495. 2008-02-19T08:19:54-00:00 2000 Information Theory, 2000. Proceedings. IEEE International Symposium on 495 antenna channel fading multi rayleigh receiver http://www.citeulike.org/user/dcastro/article/2397650 <i>Wireless Personal Communications, Vol. 26, No. 2. (2003), pp. 237-248.</i><br /><br />Abstract  Various types of multi-antenna techniques have been discussed to realize high speed data transmission in mobile communication systems. Those multiple antenna systems obtain space diversity gain by utilizing multi-paths as independent channels from transmitter and receiver. One important issue to utilize the powerful diversity gains of those multi-antenna technologies is how to create independent channels between transmitter and receiver. Almost all of conventional multi-antenna technologies have been discussed with assuming that there is not any correlation among channels between transmitter and receiver. However in realistic world this assumption is not always true and the correlation among channels becomes very high. This high correlation drastically degrades the performance of those multi-antenna technologies. In this paper we present an enhanced transmission diversity method to solve the problem of high correlation among channels. The following contents of this paper mainly focus on the Space Time Turbo Coding in OFDM systems, however the concept of the presented method can be adopted in various types of multi-antenna systems. Enhanced Multi-Antenna Technologies on OFDM for Future Mobile Communication Systems Kenichi Miyoshi Osamu Kato Atsushi Matsumoto Mitsuru Uesugi Hiroshi Suzuki doi:10.1023/A:1025586722048 Wireless Personal Communications, Vol. 26, No. 2. (2003), pp. 237-248. 2008-02-19T08:00:30-00:00 2003 Wireless Personal Communications 26 2 237 248 antenna communication mobile multi ofdm