A symbol encoder unit is configured to produce two or more encoded spatial data streams, wherein a number, NSS, of the encoded spatial data streams is less than a number, NTX, of transmission antennas to be used to transmit the encoded spatial data streams. A spatial spreading unit is configured to utilize a spatial spreading matrix Q to distribute two or more encoded spatial data streams to the transmission antennas. Q has NTX rows and NSS columns, and Q satisfies one or more of the following two constraints:  ∑ l = 1 N SS ⁢ Q ⁡ ( t , l )  2 = A t ⁢ B ( a ) for all t=1 . . . NTX., or  ∑ l = 1 N SS ⁢ S l ⁢ Q ⁡ ( t , l )  2 = A t ⁢ B ( b ) for all t=1 . . . NTX when Sl is equal to (i)−1 or (ii) 1. Q(t,l) is a component of Q at row t, column l, Sl is a symbol in an 1-th spatial stream. B is a constant, and A1, A2, . . . , ANTX is a sequence of constants.