4 research outputs found
On the Maximal Diversity Order of Spatial Multiplexing with Transmit Antenna Selection
Zhang et. al. recently derived upper and lower bounds on the achievable
diversity of an N_R x N_T i.i.d. Rayleigh fading multiple antenna system using
transmit antenna selection, spatial multiplexing and a linear receiver
structure. For the case of L = 2 transmitting (out of N_T available) antennas
the bounds are tight and therefore specify the maximal diversity order. For the
general case with L <= min(N_R,N_T) transmitting antennas it was conjectured
that the maximal diversity is (N_T-L+1)(N_R-L+1) which coincides with the lower
bound. Herein, we prove this conjecture for the zero forcing and zero forcing
decision feedback (with optimal detection ordering) receiver structures.Comment: 10 pages. Submitted to the IEEE Transactions on Information Theor
On Outage and Error Rate Analysis of the Ordered V-BLAST
Outage and error rate performance of the ordered BLAST with more than 2
transmit antennas is evaluated for i.i.d. Rayleigh fading channels. A number of
lower and upper bounds on the 1st step outage probability at any SNR are
derived, which are further used to obtain accurate approximations to average
block and total error rates. For m Tx antennas, the effect of the optimal
ordering at the first step is an m-fold SNR gain. As m increases to infinity,
the BLER decreases to zero, which is a manifestation of the space-time
autocoding effect in the V-BLAST. While the sub-optimal ordering (based on the
before-projection SNR) suffers a few dB SNR penalty compared to the optimal
one, it has a lower computational complexity and a 3 dB SNR gain compared to
the unordered V-BLAST and can be an attractive solution for
low-complexity/low-energy systems. Uncoded D-BLAST exhibits the same outage and
error rate performance as that of the V-BLAST. An SNR penalty of the linear
receiver interfaces compared to the BLAST is also evaluated.Comment: accepted by IEEE Transactions on Wireless Communication