Patent ID: 7983355
Filing Date: 2011-07-19
Classification: H04B,H04L

Abstract:
1. In a multi-antenna transmitter disposed to transmit an RF input signal through a plurality of transmit antennas so as to produce a corresponding plurality of RF output signals, said RF input signal being comprised of a plurality of subcarrier signals, an RF signal processing method comprising: adaptively bit loading said plurality of subcarrier signals in accordance with a corresponding plurality of bit loading values in order to form a corresponding plurality of bit-loaded subcarrier signals, wherein said plurality of bit loaded subcarrier signals are transported by a first transmit path and a second transmit path in the multi-antenna transmitter, wherein said adaptively bit loading comprises individually selecting a respective power scaling factor for each of said plurality of subcarrier signals so that said subcarrier signals characterized by higher signal-to-noise ratios at a remote receiver are allocated more power than said subcarrier signals characterized by lower signal-to-noise ratios at said remote receiver, and wherein said adaptively bit loading comprises individually selecting a respective modulation for each of said plurality of subcarrier signals in which a same modulation is not applied to each of said plurality of subcarrier signals; converting said plurality of bit-loaded subcarrier signals into said RF input signal in each of said first transmit path and said second transmit path; dividing said RF input signal, in each of said first transmit path and said second transmit path, in order to form a plurality of at least three divided RF signals; weighting a first of the divided RF signals from said first transmit path with a first transmit RF weighting value, weighting a first of the divided RF signals from said second transmit path with a second transmit RF weighting weight, and combining said weighted first RF signal from said first transmit path and said weighted first RF signal from said second transmit path before transmitting over a first antenna; weighting a second of the divided RF signals from said first transmit path with a third transmit RF weighting value, weighting a first of the divided RF signals from said second transmit path with a fourth transmit RF weighting weight, and combining said weighted second RF signal from said first transmit path and said weighted second RF signal from said second transmit path before transmitting over a second antenna; and weighting a third of the divided RF signals from said first transmit path with a fifth transmit RF weighting value, weighting a first of the divided RF signals from said second transmit path with a sixth transmit RF weighting weight, and combining said weighted third RF signal from said first transmit path and said weighted third RF signal from said second transmit path before transmitting over a third antenna, wherein parameters used for bit loading and transmit RF weighting values are modified as frequently as a particular communication channel changes state.