Adaptive time diversity and spatial diversity for OFDM
AssigneeNortel Networks Limited
InventorsShiquan Wu, Wen Tong, Leo Strawczynski
Life of this patent
Estimating the term…
Abstract
An adaptable orthogonal frequency-division multiplexing system (OFDM) that uses a multiple input multiple output (MIMO) to having OFDM signals transmitted either in accordance with time diversity to reducing signal fading or in accordance with spatial diversity to increase the data rate. Sub-carriers are classified for spatial diversity transmission or for time diversity transmission based on the result of a comparison between threshold values and at least one of three criteria. The criteria includes a calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix.
Claims9
A method of transmitting data, comprising:
- loading a first data on a sub-carrier of an orthogonal frequency division multiplexing (OFDM) symbol associated with an antenna;
- loading a second data on a sub-carrier of another OFDM symbol associated with the antenna;
- loading said first and said second data on sub-carriers of OFDM symbols associated with an another antenna according to a first conjugate mapping rule and a second conjugate mapping rule, to thereby produce a first mapped data and a second mapped data;
- transmitting said first data with the antenna;
- transmitting said second data with the antenna;
- and
- transmitting said first mapped data with said another antenna;
- and
- transmitting said second mapped data with said another antenna.
- wherein transmission with said another antenna are transmitted subsequent to corresponding transmission with said antenna.
A method for use with an adaptive orthogonal frequency division-multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having a format of a frame and a corresponding duration, the OFDM frame including data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the method comprising:
- loading a first data onto a sub-carrier of a first OFDM symbol corresponding to a first transmitter antenna;
- transmitting said first data within a duration of said first OFDM symbol corresponding to said first transmitter antenna;
- loading said first data onto a sub-carrier of a second OFDM symbol corresponding to a second transmitter antenna according to a first conjugate mapping rule to thereby produce a first mapped data;
- transmitting said first mapped data within a duration of said second OFDM symbol corresponding to said second transmitter antenna;
- loading a second data onto said sub-carrier of a second OFDM symbol corresponding to said first transmitter antenna;
- transmitting said second data within the duration of said second OFDM symbol corresponding to said first transmitter antenna;
- loading said second data onto a sub-carrier of a first OFDM symbol corresponding to said second transmitter antenna according to a second conjugate mapping rule to thereby produce a second mapped data;
- and,
- transmitting said second mapped data within the duration of said first OFDM symbol corresponding to said second transmitter antenna.
Dependencies are inferred from the claim text.