1 research outputs found
Cyclic Delay Transmission for Vector OFDM Systems
Single antenna vector OFDM (V-OFDM) system has been proposed and investigated
in the past. It contains the conventional OFDM and the single carrier frequency
domain equalizer (SC-FDE) as two special cases and is flexible to choose any
number of symbols in intersymbol interference (ISI) by choosing a proper vector
size. In this paper, we develop cyclic delay diversity (CDD) transmission for
V-OFDM when there are multiple transmit antennas (CDD-V-OFDM). Similar to
CDD-OFDM systems, CDD-V-OFDM can also collect both spatial and multipath
diversities. Since V-OFDM first converts a single input single output (SISO)
ISI channel to a multi-input and multi-output (MIMO) ISI channel of
order/length times less, where is the vector size, for a given
bandwidth, the CDD-V-OFDM can accommodate times more transmit antennas than
the CDD-OFDM does to collect all the spatial and multipath diversities. This
property will specially benefit a massive MIMO system. We show that with the
linear MMSE equalizer at each subcarrier, the CDD-V-OFDM achieves diversity
order , where is the transmission rate, is the number of
transmit antennas, and is the ISI channel length between each transmit and
receive antenna pair. Simulations are presented to illustrate our theory.Comment: 26 pages, 8 figures, Transaction on Wireless Communicatio