Constant-amplitude (CA) sequences are efficacious in the construction of multicarrier sounding waveforms in order to facilitate simultaneous channel estimation (SCE) in uplink multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The permissible single-root length-N Zadoff-Chu sequences that are cyclically shiftable with a minimum cyclic shift distance (CSD) ${\varpi _{{\text{min }}}}$ in time domain are widely adopted to enable the separation of simultaneously received sounding OFDM waveforms and thus achieve accurate SCE when at most $\left\lfloor {N/{\varpi _{\min }}} \right\rfloor $ MIMO channels are estimated simultaneously. To enable the large-size SCE of more than $\left\lfloor {N/{\varpi _{\min }}} \right\rfloor $ MIMO channels, nonorthogonal multiple-root Zadoff-Chu sequences have to be adopted and this degrades the SCE performance remarkably due to heavy inter-sequence interference (ISI). In this paper, various CA sequence families are thus investigated for performance prevalence in the large-size SCE over independent Rician multipath channels. It is analytically shown that the large-size SCE can be achieved with less influence from ISI when the adopted CA sequence family is composed of orthogonal sequence subfamilies, each containing as many permissible cyclically-shiftable CA sequences as possible.
Simultaneous Channel Estimation in MIMO OFDM Systems Using Constant-Amplitude Sequences
2023-10-10
1319152 byte
Conference paper
Electronic Resource
English