Construction and analysis of a new 4 x 4 orthogonal space-time block code

Construction and Analysis of Quaternion MIMO-OFDM Communications Systems

“…Channel models in Matlab standard fading functions are used to compute the frame-to-frame unit response for each OFDM symbol. This process yields H, which is to be applied to symbol codewords according to (22). Although transmission channels are, in theory, assumed to be static over the entire codeword C, vector Y will contain the channel evolution over M b OFDM symbols and will be degraded by noise components.…”

“…An orthogonal design that has entries that are linear combinations of the permitted variables of the respective sets is said to be a design that performs linear processing. Calderbank et al proposed a quaternion based QOD [22], but it was not with linear processing.…”

Unitary Differential Space–Time Modulation With Joint Modulation

“…It should also be noted that the use of joint modulation enables our DSTM schemes to flexibly support various spectral efficiency values. This is not possible for the O-STBC and QO-STBC DSTM schemes proposed in [15] and [16].…”

“…However, such reduction in decoding complexity is obtained with a sacrifice in the decoding performance, and its maximum achievable code rate is limited to three fourths for four antennas and one half for eight antennas. To trade decoding complexity for performance, a nonunitary DSTM scheme based on a quasiorthogonal STBC (QO-STBC) and a unitary DSTM scheme based on a unitary nonlinear STBC have been proposed in [15] and [16], respectively. Both support full rate (code rate = 1 symbol/channel use) for four transmit antennas, and both are pairwise decodable with a decoding search space in between √ N and 3 √ N per decoder.…”

“…The DSTM encoder of [15] also has a higher computational complexity as it needs to solve a set of linear equations for every codeword to be transmitted. As compared with the schemes from [16], our proposed designs can be extended to pairwisedecodable QO-STBCs of any number of transmit antennas and are able to support a wide range of spectral efficiencies, whereas those in [16] are not known to exhibit such flexibility.…”