N. Yee, and J.-P. Linnartz, "Controlled Equalization of MultiCarrier CDMA in an Indoor Rician Fading Channel," in Proc. 43th IEEE Veh. Technol. Conf., pp. 1670--1674, 1994.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....To achieve multiuser capability, traditional code division multiple access (CDMA) can be introduced, however in the frequency domain, so that the uth user code signal is given by (t) C k e ,u=1, U. 5) First approaches for MC SS CDMA receiver architectures are given in [22] and [23] In [24] joint detection receiver architectures (those imply a time domain view) have been investigated Sync SAW Synthesizer Osc. Fig. 5: Low cost terminal architecture and proposed for MC SS. In [25] channel estimation techniques known from DS SS are adopted to MC SS. And in [26] ....

N. Yee, and J.-P. Linnartz, "Controlled Equalization of MultiCarrier CDMA in an Indoor Rician Fading Channel," in Proc. 43th IEEE Veh. Technol. Conf., pp. 1670--1674, 1994.

....systems described above such that and . As noted above, it will be assumed that the system is using random scrambling sequences. Although better performance can be obtained in a multiuser environment where the users are equally faded by using sequences that are orthogonal to those of other users [19], the work here will be concerned with the mobile to base link where the independent Rayleigh fading between users randomly changes the phase of the spreading sequences on each slot. However, the systems introduced here enjoy the same eigenfunction interpretation that is exploited directly by the ....

....with the mobile to base link where the independent Rayleigh fading between users randomly changes the phase of the spreading sequences on each slot. However, the systems introduced here enjoy the same eigenfunction interpretation that is exploited directly by the simple gain equalization in [19]. C. Qualitative Interpretation The total number of users per slots is given as the product of the number of users per group and the number of Fig. 4. Interpretation of the class of systems. groups as , where the user density is defined as users slot. The total number of users in the system is ....

N. Yee and J. Linnartz, "Controlled equalization of multi-carrier CDMA in an indoor Rician fading channel," in Proc.

.... we find the Maximum Likelihood Sequence Estimation (MLSE) detector and the Minimum Mean Square Error (MMSE) detector [3] Beside the knowledge of CSI, some of these improved detection schemes require information about the number of active users as well as the additive noise power [3] 4] [5], 6] 7] 8] Other proposed detection schemes are based on a multi stage detector type or detection with multiple iterations [9] 10] 11] The obtained performance with these schemes is much related to their complexity. As we are dealing with the downlink of a cellular radio system where ....

....2 n N u # 2 s , 8) which is a function of both the channel attenuation factor, the additive noise variance # 2 n , the number of active users, and the signal power. With that the system becomes less sensitive to the load variation and better average bit error probability is obtained [2] [5], 9] C. Simulation Results To illustrate the performance of these detection schemes we consider a MC CDMA with a total of N u = 64 active users. The spreading codes are derived from the 64 64 Walsh Hadamard matrix. We study the system performance with a full load and for two di#erent fading ....

N. Yee and J.-P. Linnartz, "Controlled equalization of multi-carrier CDMA in an indoor Rician fading channel, " Proc. VTC '94, Stockholm, Sweden, May 1994, p. 1665-1669.

....performance that cannot be reduced by just increasing the transmitted power. Many MC CDMA detectors have been proposed in the literature and analyzed. The simplest is a conventional correlator detector with Channel State Information (CSI) called Orthogonality Restoring Correlation (ORC) detector [3]) This technique illuminates the error floor, but at the expense of a noise amplification, giving an overall system performance worse than that of conventional OFDM scheme. In reducing this noise amplification, a correlator detector with Threshold (TORC) has been studied in [2] 8] and a TORC ....

N. Yee and J.-P. Linnartz, "Controlled equalization of multicarrier CDMA in an indoor Rician fading channel," Proc. IEEE VTC '94, pp. 1665-1669, Stockholm 1994.

....th user in the l th slot. I k;l (t) indicates the combined interference (both multiuser and additive white Gaussian noise) that the k th user sees on the l th channel. Note that the system shown here when the coding is simple spreading is similar to the multicarrier systems put forward in [5, 6] and the time spread spread spectrum system of [7] The correlation receiver considered on each frequency channel is shown in Figure 3. Note that maximum ratio combining is performed; in other words, under Gaussian assumptions on the interference, the optimal combining given knowledge of only the ....

N. Yee and J. Linnartz, "Controlled Equalization of Multi-Carrier CDMA in an Indoor Rician Fading Channel," Proceedings of the 1994 Vehicular Technology Conference, pp. 1665-1669, June 1994.

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