A universal MIMO approach for 3GPP wireless standards

We propose a generalized framework for handling Multiple-Input Multiple-Output (MIMO) schemes defined within the context of the Third Generation Partnership Project (3GPP) physical layer specifications. A detailed review of all the multi-antenna transmission techniques adopted by the 3GPP so far is firstly presented, starting from the Global System for Mobile (GSM) communications and passing through the High-Speed Packet Access (HSPA) releases to the very recent Long Term Evolution (LTE)-Advanced standard. Motivated by the outcome of this overview, we introduce the Transmit Matrix (TRAM) concept, that can include as special cases several MIMO systems (e.g. transmit diversity, spatial-multiplexing, etc.) regardless of the presence or not of a feedback channel. Our approach is based on the adoption of a novel measure called Necessary Transmit Information (NTI) and on its one-to-one correspondence with the TRAM. The last allows for a convenient alternative representation of a TRAM-based MIMO system model and serves the straightforward construction of NTI-codebooks for a wide range of transmission schemes. The indicative applications provided reveal the universal nature of the proposed methodology.