OFDM-MIMO radio frequency transmission system

摘要

An OFDM-MIMO radio-frequency transmission system takes the form of a DVB-T system which is modified in that the phases of selected ones of the pilot signal transmissions, particularly the scattered pilots, are chosen or changed at the transmitters such that some of the corresponding pilot signal transmissions from the two (or more) MIMO transmitter stages are in the same phase and others of the transmissions are with relatively-inverted phase. At a receiver the received pilot signals 10 are extracted and combined so as to obtain an indication of the transmission channel characteristics. There are three improvements: (i) any continual pilots on the same carrier as inverted scattered pilots are also inverted in phase, (ii) those scattered pilots on alternate pilot-bearing carriers are phase inverted, even if this means that a given symbol has some inverted and some non-inverted, and (iii) at the receiver the non-inverted and inverted pilots are separated, interpolated in frequency and time, and then both added and subtracted.