Demodulation Reference Signal Pattern Multiplexing for 8-Antenna LTE Systems

The patent divides the DRS patterns into two distinct groups: patterns that are frequency-shifted relative to the physical downlink shared channel (PDSCH) resource blocks, and patterns that are not frequency-shifted. This segmentation allows the system to define up to 8 distinguishable patterns by combining different frequency shift values with different antenna ports, while still defining patterns in units of RBs to maintain low overhead. The frequency-shifted patterns provide additional distinguishable patterns without increasing the base overhead structure.

The patent applies different properties to different DRS pattern groups: frequency-shifted patterns use a frequency shift offset relative to the PDSCH resource blocks, while non-frequency-shifted patterns use the same frequency location as the PDSCH resource blocks. This local differentiation allows legacy systems to interpret the non-frequency-shifted patterns in their traditional manner, while new systems can utilize both frequency-shifted and non-frequency-shifted patterns to achieve up to 8 distinguishable patterns with reduced overhead.

The patent uses parameter changes to create distinguishable DRS patterns: it varies the frequency shift offset parameter and the antenna port parameter. By changing these parameters, the system can define up to 8 distinguishable patterns without creating entirely new pattern structures. The frequency shift offset can take different values (e.g., 0, 1, 2, 3) and combines with antenna port indices to provide the required 8 distinguishable patterns, simplifying the definition process compared to creating completely independent patterns for each antenna.