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The communication between a multiple-antenna transmitter and multiple receivers (users) with either a single or multiple-antenna each can be significantly enhanced by providing the channel state information at the transmitter (CSIT) of the users, as this allows for scheduling, beamforming and multiuser multiplexing gains. The traditional view on how to enable CSIT has been as follows so far: In time-division...
In a system comprising of a multiple antenna enabled base station (BS) and multiple single antenna users, very high data rates can be obtained if BS transmits to multiple users simultaneously. This simultaneous transmission to multiple users over the same bandwidth is realizable only if BS knows the forward channels linking its transmit antennas to these users. We study a time-division duplexed (TDD)...
Simultaneous transmission of multiple data streams from a multiple antenna base station (BS) to multiple single antenna users gives significant gain in spectral efficiency as compared to when a single such user is being served. This simultaneous transmission to multiple users is realizable only if BS knows the forward channels linking its transmitting antennas to these users which requires channel...
The absolute gain of multi-user diversity in the context of a downlink channel is the focus of this contribution. Enjoying multi-user diversity gain first requires the channel information availability at the transmitter (CSIT) in a normal downlink (DL) system. Although multi-user diversity gains have been specified well, but the burden of exchange of information required is not rigorously accounted...
A multiuser MIMO system is considered with no initial assumption of channel state information (CSI) at any of the receivers or the BS transmitter. For a system working under frequency-division duplexing (FDD) mode, simple practically realizable transmission strategy is proposed which provides necessary channel state information to both sides with minimal resource utilization for downlink (DL) data...
In this paper, we consider stationary time- and frequency-selective MIMO channels. No channel knowledge neither at the transmitter nor at the receiver is assumed to be available. We investigate the capacity behavior of these doubly selective channels as a function of one of the system parameters, the number of transmit antennas and channel parameters as delay spread, Doppler bandwidth and channel...
The asymptotic capacity for the non-coherent MIMO stationary channels having nt transmit and nr receive antennas with flat fading is the focus of this paper. Fading processes of concern are bandlimited. These non-coherent MIMO channels were studied by Etkin and Tse and lower bound of capacity was shown to grow with min(nt, nr)[1 - min(nt, nr)mu] log(SNR) where mu is the normalized Doppler bandwidth...
We analyze a broadcast channel with no initial assumption of channel state information neither at the base station (BS) nor at the users' side. For the case when there is no possibility of feedback to the BS and it remains oblivious of the channel state information throughout the transmission, it is shown that the capacity region is bounded by the capacity of a point-to-point MISO link and hence the...
In this paper, we consider stationary time- and frequency-selective channels. No channel knowledge neither at the transmitter nor at the receiver is assumed to be available. We investigate the capacity behavior of these doubly selective channels as a function of the channel parameters delay spread, Doppler bandwidth and channel spread factor (the product of the delay spread and the Doppler bandwidth)...
We continue previous work [1] in which we analyzed the Mutual Information of Frequency-Flat MIMO Channels with a Block Fading model. Absence of Channel State Information at Transmitter or Receiver (no CSIT/CSIR) was considered there. It was shown that implicitly a (semi-blind) channel estimate needs to be constructed that, in decision-feedback style, depends on the past (detected) inputs and outputs...
This paper investigates the problem of channel quality indicator (CQI) estimation in the context of OFDMA systems in the downlink. The problem of CQI estimation is addressed for SINR-based CQI forms. In this paper, we present a technique for instantaneous SINR estimation which consists in using the channel estimator already present at the receiver to obtain the useful signal levels and signal regeneration...
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