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SU and MU-MIMO performance relies on accurate link adaptation in order to benefit from multi-user scheduling, beamforming, adaptive coding and modulation. Such accuracy highly depends on the type of the channel state information feedback. LTE-Advanced has defined two major types of feedback, i.e. implicit and explicit feedback. Implicit feedback makes some assumptions on the transmit precoding and...
In order to fully benefit from multiple-input multiple-output (MIMO) channels, multiuser techniques are adopted in the 3rd generation partner project (3GPP) long term evolution (LTE) downlink system. The core task of multiuser MIMO system is to suppress multiuser interference and enhance the signal to interference plus noise ratio (SINR). As a classical MIMO scheme, block diagonalization (BD) algorithm...
We propose a linear precoding technique, called multiuser generalized eigenmode transmission (MGET), based on the leakage-based precoding technique. A signal-to-leakage-plus-noise (SLNR) precoding scheme is one approach for linear precoding in the multiple-input multiple-output broadcast channel that sends multiple data streams to different users in the same cell. Unfortunately, SLNR-based scheme...
In this paper, we develop a general mathematical framework to incorporate dynamic spectrum access in a multiuser MIMO network. This framework is particularly helpful in computing the maximum achievable system capacity of a resulting multiple-band multiuser MIMO network. The mathematical formulation to maximize the system capacity is shown to be quite similar to that of a well studied single-band multiuser...
Opportunistic Spatial Orthogonalization (OSO), first proposed in Shen and Fitz (2009) for the single-input-multiple-output (SIMO) system, is a cognitive radio scheme that opportunistically allows the existence of secondary users even if the primary user occupies all the frequency bands all the time. On one hand, OSO can be viewed as a multi-user diversity scheme that exploits the channel randomness...
For multiuser multiple-input multiple-output (MIMO) uplink communications where the signal-to-interference-plus-noise ratio (SINR) of the k-th user, denoted as SINRk, is expected to achieve the target value gammak, we first consider the ideal scenario where multiuser channel matrices are perfectly known to every user and we solve the problem of maximizing mink(SINRk/gammak) over all possible beamformers...
We investigate the performance of limited feedback zero forcing beamforming-based MU-MIMO in correlated channels when users have the opportunity to adapt their codebooks as a function of their own channel statistics (CDIT). An upper bound on the rate loss is derived in terms of the amount of feedback and the statistics of the channel. In order to maintain a constant rate loss with respect to the perfect...
We consider a spectrum sharing based cognitive radio network where a secondary mulitple-input multiple-output (MIMO) communication link coexists with a primary user by opportunistically utilizing the transmit spectrum originally allocated to the primary user. The secondary link employs orthogonal space-time block coding (OSTBC) at the transmitter and maximum likelihood (ML) decoding at the receiver...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
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