PU2RC

From Wikipedia, the free encyclopedia

Per-User Unitary Rate Control (PU2RC) is the world first codebook based multi-user MIMO platform[1], which is a similar to world-wide OS platforms in computing technology such as Linux (cooperative OS development platform), Symbian, Mac OS X, Windows. It also shows an example of how to use transmit precoding and user scheduling efficiently.

On the other hand, R. Heath and et. al have discussed multiuser MIMO scheduling[1]. A. Kogiantis and et al. have analysized optimal power allocation for MISO multiuser scheduling channels[2]. Earlier than two papers, K.K. Wong and et al. have considered a full CSIT based precoding scheme of multiuser MIMO system[3].

  • Background technologies
[1] R. W. Heath, Jr., M. Airy, and A. J. Paulraj, "Multiuser Diversity for MIMO Wireless Systems with Linear Receivers," Proc. of the IEEE Asilomar Conf. on Signals, Systems, and Computers, pp. 1194 -1199, vol.2, Pacific Grove, California, Nov. 4 - 7, 2001.
[2] A. Kogiantis and L. Ozarow, "Downlink best-effort packet data with multiple antennas," ICC’03, Volume 1, 11-15 May 2003 Page(s):715 - 719.
[3] K.K. Wong, R.D. Murch and K.B. Letaief, "Performance Enhancement of Multiuser MIMO Wireless Communication Systems," IEEE Transactions on Communications, Vol 50 No 12 , Dec. 2002, pp 1960 –1970

Contents

[edit] Technology

PU2RC allows the network to allocate each antenna to the different user, unlike in single-user MIMO scheduling. Instead of a physical antenna, the network can transmit to a user through a codebook based spatial beam, i.e., a virtual antenna. Additionally, efficient user scheduling such as pairing spatially distinguishable users with codebook-based spatial beams is used for the simplification of wireless networks in terms of additionally required wireless resource and complex protocol modification.

[edit] Mathematical description

Throughput performance of PU2RC over the single-user & no scheduling scheme
Throughput performance of PU2RC over the single-user & no scheduling scheme

The operation is described mathematically below for the transmitter and receiver side.

[edit] Transmitter Side

The transmitter antenna array has Nt elements. The transmit signal vector is modeled as follows:

\mathbf{x} = \sum_{i=1}^K \mathbf{w}_i P_i s_i

where \mathbf{x} is the N_t \times 1 vector of transmitted symbols and \mathbf{w}_i is the N_t \times 1 linear precoding vector. PU2RC generates {\mathbf{w}_i} based on the received finite channel status information, which is delivered to the base station by the user equipment (UE) using a coded look-up table index.

[edit] Receiver Side

Every receiver has a receive antenna array with Nr elements. The receive signal vector at user k (=1,2,\ldots,K) is modeled as follows:

\mathbf{y}_k = \mathbf{H}_k\mathbf{x}+\mathbf{n}_k

where \mathbf{y}_k and \mathbf{n}_k are the N_r \times 1 received symbol and noise, respectively, and \mathbf{H}_k is the N_t \times N_r matrix with the channel coefficients.

[edit] Throughput performance

The figure illustrates the throughput advantage of PU2RC over the conventional single-user and no scheduling scheme, assuming that the codebook size is one, i.e., (G = 1). For larger codebook sizes the performance can be better than the performance of the unit-size codebook. Because of codebook-based multi-user scheduling, PU2RC outperforms the conventional single-user and no scheduling scheme when the number of users is larger than one. Note that the performance plotted in the figure for the two systems were obtained assuming linear receiver.

[edit] See also

[edit] Books

[edit] PU2RC reference materials and sites

[edit] Codebook and Signal Processing

  • Quantized Principal Component Selection Precoding for Limited Feedback Spatial Multiplexing, 2006 ICC
  • System level performance evaluation of spatial multiplexing with per common basis rate control, 2005-fall VTC
  • Multimode basis selection for spatial multiplexing with limited feedback, 2005 Electronics Letters

[edit] Feature added contributions

[edit] MU-MIMO papers

[edit] Internal pages

[edit] References

  1. ^ Niranjay Ravindran, Nihar Jindal, and Howard Huang (November 2007). "Beamforming with Finite Rate Feedback for LOS MIMO Downlink Channels". To Appear: IEEE Global Communications Conference.