B. R. Voj cic and W. M. Jang, "Transmitter precoding in synchronous multiuser communications," IEEE Trans. Commun., vol. 46, no. 10, pp. 1346--1355, Oct. 1998.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....sequences that are an optimum ensemble for all users. We note, however, that although they address fundamentally different problems, a single signature sequence update of [11] and that of this paper are essentially the same. A related topic to signature sequence design is transmitter precoding [12]. In transmitter precoding, the transmit signals intended for multiple users are passed through a linear transformation at the common transmitter (base station) to minimize the MAI at the remote receivers (users) Transmitter precoding assumes that the bits of the users on the downlink are already ....

....on the downlink are already modulated with some linearly independent signature sequences, and essentially undoes the cross correlation introduced by the non orthogonality of these signature sequences. The optimum linear transformation was found to be the inverse of the cross correlation matrix in [12]. Intrinsically, 12] assumes that the number of users is less than the processing gain, so that this cross correlation matrix is invertible. Receiver optimization in conjunction with transmitter precoding was studied in [13] It is worth mentioning that transmitter beamforming in systems with ....

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B. R. Vojcic and W. M. Jang. Transmitter precoding in synchronous multiuser communications. IEEE Transactions on Communications, 46(10):1346--1355, October 1998.

....This overhead is especially problematic in the forward link of a cellular mobile network where the receiver is usually a highly resource constrained mobile unit. Recently, approaches have been proposed which transfer some or all of the processing burden from the receiver to the transmitter (see [1], 2] 3] and [4] These methods work by applying a linear transformation to both the transmitted signals and the outputs from the bank of matched filter detectors. By using the minimum mean squared error criterion, the transformations can be selected to minimize the bit error rate due to the ....

....to both the transmitted signals and the outputs from the bank of matched filter detectors. By using the minimum mean squared error criterion, the transformations can be selected to minimize the bit error rate due to the MAI. The least complex of these methods is transmitter precoding [1] [4] It is shown in [1] that transmitter precoding results in complete decorrelation of the transmitted symbols. In a noiseless channel, this is equivalent to the well known decorrelating detector. However, by applying the decorrelation operation at the transmitter before noise is added to the ....

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B. R. Vojoic and W. M. Jang, "Transmitter precoding in synchronous multiuser communications," IEEE Transactions on Communications, vol. 46, no. 10, pp. 1346--1355, Oct. 1998.

....every user. This concept is displayed in Fig. 1, where the function in Fig. 1(b) has to be optimized in terms of multiuser interference minimization. In [12] such an approach was considered for a single path channel only and a solution for the multipath channel was proposed by Vojcic and Jang in [13], which however requires the use of Rake receivers for a reasonable performance. Further joint precoding techniques were recently suggested in [14] 17] In Section II, our system model will be described. We will then derive in Section III the optimum precoding method such that the interference ....

....they would in a single user single path system. Ignoring noise, and assuming a unit gain channel, we want for any and , or, in vector form (24) There are several ways in which we can completely eliminate both the multiuser and the multipath interference, one solution was obtained for instance in [13]. Depending on the method employed, interference elimination requires a certain transmit power that is usually greater than the one required with conventional spreading. In real systems, however, power is limited, and the transmit power will have to be normalized to the available transmit power . ....

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B. R. Vojcic and W. M. Jang, "Transmitter precoding in synchronous multiuser communications," IEEE Trans. Commun., vol. 46, pp. 1346--1355, Oct. 1998.

....This overhead is especially problematic in the forward link of a cellular mobile network where the receiver is usually a highly resource constrained mobile unit. Recently, approaches have been proposed which transfer some or all of the processing burden from the receiver to the transmitter (see [2], 3] 4] 5] These methods work by applying a linear transformation at either the transmitter side [2] 4] 5] or at both the transmitter and receiver sides [3] By using the minimum mean squared error criterion, the transformations can be selected to minimize the bit error rate due to the ....

....is usually a highly resource constrained mobile unit. Recently, approaches have been proposed which transfer some or all of the processing burden from the receiver to the transmitter (see [2] 3] 4] 5] These methods work by applying a linear transformation at either the transmitter side [2], 4] 5] or at both the transmitter and receiver sides [3] By using the minimum mean squared error criterion, the transformations can be selected to minimize the bit error rate due to the MAI. Reference [4] studies a transmitter precoding scheme tailored to exploit multi path components, as ....

[Article contains additional citation context not shown here]

B. R. Vojoic and W. M. Jang, "Transmitter precoding in synchronous multiuser communications," IEEE Transactions on Communications, vol. 46, no. 10, pp. 1346--1355, Oct. 1998.

....JT would be especially suited for the downlink of radio transmission systems employing TDD. In JT the transmit signal design ist based on channel state knowledge. In this sense JT is related to transmit signal preprocessing schemes published in [6, 7] for fixed wired transmission and in [8, 9, 10, 11, 12] for wireless transmission. Besides to the elimination of ISI and MAI, JT offers the possibility to take further transmit signal optimization criteria into account while generating the common transmit signal. Whereas in [2, 3, 4, 5] only transmit signal energy minimization is pursued, in this ....

B.R. Vojcic and J.W. Mee, "Transmitter precoding in synchronous multiuser communications", IEEE Transactions on Communications, vol. 46, no. 10, pp. 1346--1355, 1998.

....linear transmitter based interference mitigation techniques. The transmitter has knowledge of all users spreading codes and CIRs. The pre RAKE [1] moves the conventional RAKE processing from Rx to Tx, but suffers from multiple access interference (MAI) The linear methods which cancel interference [2 8], but do not regard noise, are known as Joint Transmission, Transmitter Precoding, Joint Predistortion and Joint Signal Precoding. An overview can be found in [10] In this paper, their system capacity enhancement capabilities are compared. Using multiple antennas in Tx and Rx, their performance ....

....Pu. ru. The U received signals are stacked to form = P.r = P.U.Vrx.C. d P.n, C (6) 3. Linear Transmitter Based Interference Mitigation Schemes The interference can be mitigated by linearly preprocessing the data symbols using the precoding matrix T. There exist several proposals to optimize T [2 8] either zero forcing (ZF) or fulfilling minimum mean square error (MMSE) criterion. For fairness comparison, the transmitted power has always to be normalized. To simplify the notation, the CLI.N x U.N) system matrix A is introduced. Note that, this system matrix is always square and signal ....

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B. Voj6i6 and W.M. Jang, "Transmitter Precoding in Synchronous Multiuser Communications, IEEE Trans. on Comm. Vol.46, No.10, p.1346-1355 (1996)

....(MSs) have to be low cost and simple as possible. In time division duplex (TDD) systems, the base station (BS) can estimate the instantaneous channel impulse response during the reception in the uplink and is able to design transmit filters which suppress the interference at the receiver (e.g. [1]) maximize the received signal portion due to the desired signal (e.g. 2, 3] or find a trade off between interference suppression and signal maximization [4, 5] However, the instantaneous downlink channel state information is not available at the BS in frequency division duplex (FDD) ....

B.R.Vojcic and W. M. Jang, "Transmitter Precoding in Synchronous Multiuser Communications," IEEE Transactions on Communications, vol. 46, no. 10, pp. 1346--1355, October

....Thus, it is desired to use the transmitter based techniques. Recently, various transmitter based techniques have been proposed. Schemes such as transmit antenna diversity [3] and pre rake diversity combining [5] 6] focus on exploiting diversity, and schemes such as transmitter precoding [7], decorrelating prefilter and jointly optimized sequence [8] focus on interference rejection in multiuser environment. These schemes achieve efficient improvement of down link capacity but have several limitations which will be described below. Transmit antenna diversity has been proposed for ....

....in pre rake diversity combining technique. The pre rake technique still has the remaining self interference due to the multiple path interference (MPI) Moreover, the pre rake technique does not consider multiple access interference (MAI) On the other hand, in transmitter precoding scheme [7], the BS removes MAI and MPI in advance by transforming the data signals appropriately before transmission. However, this scheme includes the receiver based rake processing to exploit multipath channel gains. Therefore, it still leaves the complexity at MS. In [8] the decorrelating prefilter and ....

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B. R. Voj#i and W. M. Jang, "Transmitter precoding in synchronous multiuser communications," IEEE Trans. Commun., vol. 46, pp. 1346-1355, Oct. 1998.

....addition to the usual assumptions, channel state information (CSI) is available at the transmitter. This is naturally the case for time division duplex systems, otherwise it can be accomplished via some backward channel. Having CSI available at the transmitter, techniques such as pre equalization [4, 5] and loading [6] i.e. an adaption of the transmit signal to the current channel characteristic, can be applied. The structure of the paper is as follows: After a short section on the channel model considered, we dis cuss the concept of decision feedback equalization. Then the V BLAST algorithm ....

B. R. Voji6 and W. M. Jang. Transmitter Precoding in Synchronous Multiuser Communications, IEEE Trans. Comm., Vol. 46, No. 10, October 1998.

....literature from a capacity point of view, see e.g. 5] and the references therein, where also asymptotically optimum, i.e. capacity achieving, precoding strategies have been proposed. Moreover, it has been proved that nonlinear precoding is superior to linear preequalization as presented e.g. in [1]. In this contribution, we focus on practical aspects of precoding for decentralized receivers. In particular, our aim is to achieve high spectral e# ciencies. Hence, we focus on the zero forcing solution, which coincides with the minimum mean squared error approach in the region of interest. ....

B.R. Vojcic, W.M. Jang. Transmitter Precoding in Synchronous Multiuser Communications. IEEE Tr. Comm., pp. 1346--1355, Oct. 1998.

....e(n) Fig. 5. NxN MIMO system with transmit pre emphasis filter and receiver scaling. An important constraint in the design of the transmit preemphasis filter is the range of the transmitter output signal. A transmitter precoding solution with an average power constraint was given in [6]. However, the multi GSa s highspeed link system requires a probability of error smaller than , which implies that clipping noise cannot be tolerated. This leads to the adoption of a peak transmit power constraint, instead of the usual average power constraint. In addition to this, adaptive ....

B. R. Voj#i# and W. M. Jang, Transmitter Precoding in Synchronous Multiuser Communications, IEEE Transactions on Communications, vol. 46, no. 10, October 1998, pp. 1346-55.

.... In the downlink, where all users share one common multipath channel, it has been shown that appropriately designed precoding guarantees identifiability of the users symbols regardless of the underlying channel [19] Various (non)blind equalizers have also been derived in [19] and [20] see also [29] and [27] for fractionally spaced detectors) In the uplink however, no existing system guarantees complete MUI cancellation and identifiability of the users symbols without restrictions on the multipath channels involved. Relying on block symbol spreading, we develop in this paper a ....

B. R. Voj cic and W. M. Jang, "Transmitter precoding in synchronous multiuser communications," IEEE Trans. Commun., vol. 46, pp. 1346--1355, Oct. 1998.

.... In the downlink, where all users share one common multipath channel, it has been shown that appropriately designed precoding guarantees identifiability of the users symbols regardless of the underlying channel [19] Various (non )blind equalizers have also been derived in [19] and [20] see also [29] and [27] for fractionally spaced detectors) In the uplink however, no existing system guarantees complete MUI cancellation and identifiability of the users symbols without restrictions on the multipath channels involved. Relying on block symbol spreading, we develop in this paper A ....

B. R. Vojcic and W. M. Jang, "Transmitter precoding in synchronous multiuser communications," IEEE Transactions on Communications,vol. 46, no. 10, pp. 1346--1355, Oct. 1998.

....It was pointed out in [9] that if the number of users is below a critical number, this iterative procedure yields a signature sequence for the desired user which is orthogonal to the signature sequences of the interfering users. A related topic to signature sequence design is transmitter precoding [10]. In transmitter precoding, the transmit signals intended for multiple users are passed through a linear transformation at the common transmitter (base station) to minimize the MAI at the remote receivers (users) Transmitter precoding assumes that the bits of the users on the downlink are already ....

....on the downlink are already modulated with some linearly independent signature sequences, and essentially undoes the cross correlation introduced by the non orthogonality of these signa6 ture sequences. Optimum linear transformation was found to be the inverse of the cross correlation matrix in [10]. Intrinsically, 10] assumes that the number of users is less than the processing gain, so that this cross correlation matrix is invertible. Receiver optimization in conjunction with transmitter precoding was studied in [11] It is also worth mentioning that the topic of transmitter beamforming ....

[Article contains additional citation context not shown here]

B. R. Vojcic and W. M. Jang. Transmitter precoding in synchronous multiuser communications. IEEE Transactions on Communications, 46(10):1346--1355, October 1998.

No context found.

B. R. Voj cic and W. M. Jang, "Transmitter precoding in synchronous multiuser communications," IEEE Trans. Commun., vol. 46, no. 10, pp. 1346--1355, Oct. 1998.

No context found.

B. R. Vojci'c and W. M. Jang. Transmitter Precoding in Synchronous Multiuser Communications. IEEE Trans. Commun., 46(10):1346--1355, Oct 1998.

No context found.

B. R. Vojcic and W. M. Jang, "Transmitter precoding in synchronous multiuser commmunication," IEEE Trans. on Communications, vol. 46, no. 10, pp. 1346--1355, Oct. 1998.

No context found.

B. R. Vojcic and W. M. Jang, "Transmitter precoding in synchronous multiuser commmunication," IEEE Trans. on Comm., vol. 46, no. 10, pp. 1346--1355, Oct. 1998.

No context found.

B. R. Vojcic and W. M. Jang, "Transmitter Precoding in Synchronous Multiuser Communications," IEEE Transactions on Communications, vol. 46, no. 10, pp. 1346-- 1355, October 1998.

No context found.

B. R. Vojcic and W. M. Jang, Transmitter precoding in synchronous multiuser communications, IEEE Transactions on Communications, vol. 46, no. 10, pp. 13461355, 1998.

No context found.

B. R. Vojcic and W. M. Jang, "Transmitter precoding in synchronous multiuser commmunication," IEEE Trans. on Comm., vol. 46, no. 10, pp. 1346--1355, Oct. 1998.

No context found.

B. R. Vojcic and W. M. Jang, "Transmitter precoding in synchronous multiuser communication," IEEE Trans. Comm., vol. 46, no. 10, pp. 1346--1355, Oct 1998.

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