Rank step-down for MIMO SCW design employing HARQ

摘要

Systems and methodologies are described that facilitate reducing rank (e.g., of a user device) as a number of transmissions there from increases. Such rank step-down can improve interference resistance and facilitate maintaining code rate despite transmission propagation. Additionally, rank step-down information can be encoded along with CQI information to generate a 5-bit CQI signal that can facilitate updating a user's rank upon each CQI transmission (e.g., approximately every 5 ms). The described systems and/or methods can be employed in a single code word (SCW) wireless communication environment with a hybrid automatic request (HARQ) protocol.

主权项

1. A method of performing rank step-down to preserve code rate across multiple transmissions in a transmission frame, comprising:
generating a plurality of coded symbols at an access point; updating a MIMO transmission rank in a deterministic manner to reflect a rank step down sequence such that the MIMO transmission rank is reduced with successive transmissions, wherein the MIMO transmission rank is determined based on spectral efficiency, modulation, code rate, and transmission number; demultiplexing the coded symbols to determine a value, M, of MIMO layers with information symbols and (MT−M) MIMO layers with erasure symbols, where M and MT are integers and 1≦M≦MT; and spatially mapping M layers using a spatial mapping matrix.