Method and apparatus for transmission within a multi-carrier communication system
Multiple transmit antenna transmission together with preferably pseudo-random, antenna-specific, scrambling (PRAS) is utilized to scramble incoming data differently on different antennas for those users requiring frequency diversity type transmissions. When PRAS is activated for a particular allocation, each transmit antenna applies a different scrambling sequence to the data symbols that are transmitted in the allocation.
1. A method for multiple antenna transmission, the method comprising the steps of:
receiving a first set of data symbols for transmission;
scrambling the first set of data symbols on a first antenna path based on a first predetermined scrambling sequence;
transmitting the scrambled data symbols from a first antenna on the first antenna path over a first set of time-frequency symbol positions;
transmitting the first set of data symbols from a second antenna on a second antenna path on the first set of time-frequency symbol positions;
wherein the first and the second antenna paths exist within a single sector of a base station.
2. The method of claim 1 , further comprising
transmitting a first pilot symbol from the first antenna; and
transmitting a second pilot symbol from the second antenna.
3. The method of claim 1 wherein the step of scrambling the first set of data symbols comprises scrambling the first set of data symbols with an antenna-specific scrambling sequence.
4. The method of claim 1 further comprising the step of:
scrambling the first set of data symbols on the second antenna path with a second predetermined scrambling sequence that differs from the first scrambling sequence; and
wherein the step of transmitting the first set of data symbols from the second antenna comprises the step of transmitting the first set of data symbols scrambled with the second predetermined scrambling sequence.
5. The method of claim 1 , wherein the first set of data symbols is based on data that has been pre-processed to introduce memory among the first set of data symbols.
6. The method of claim 1 , wherein a target receiver of the transmission has knowledge of the first scrambling sequence, and has knowledge that the transmission comprises a first and second antenna path.
7. The method of claim 1 further comprising
receiving a second set of data symbols for transmission;
transmitting the second set of data symbols on a second set of time-frequency symbol positions from the first antenna as scrambled or unscrambled data symbols; and
transmitting the scrambled or unscrambled data symbols on the second antenna.
8. The method of claim 7 wherein the time positions of the first set of time-frequency symbol positions coincide with the time positions of the second set of time-frequency symbol positions
9. The method of claim 1 wherein a data symbol from the first set of data symbols to be transmitted from the second antenna and the corresponding scrambled data symbol to be transmitted from the first antenna are transmitted on the same time-frequency position within the first set of time-frequency positions.
10. The method of claim 1 further comprising:
receiving a second set of data symbols for transmission;
transmitting the second set of data symbols from the first and second antennas over a second set of time-frequency symbol positions using cyclic shift diversity.
11. The method of claim 1 further comprising the steps of:
receiving a second set of data symbols;
transmitting the second set of data symbols over a second set of time-frequency symbol positions from the first and second antennas, wherein one or more beamforming weights for the second set of data symbols are applied to one or both of the first and second antenna paths.
12. The method of claim 1 further comprising
receiving a second set of data symbols for transmission;
performing one or both of (a) and (b):
(a) scrambling the second set of data symbols on the first antenna path based on a second predetermined scrambling sequence;
(b) scrambling the second set of data symbols on the second antenna path based on a third predetermined scrambling sequence;
transmitting the second set of data/scrambled data symbols from the first antenna on the first antenna path over the first set of time-frequency symbol positions;
transmitting the second set of data/scrambled symbols from the second antenna on the second antenna path over the first set of time-frequency symbol positions.
13. The method of claim 1 wherein the step of scrambling the first set of data symbols is performed in the frequency domain
14. The method of claim 1 wherein the first set of time-frequency positions are concurrent in time but on different subcarriers.