A Pragmatic Approach to Massive Multiple Input Multiple Output (MIMO) for Satcoms

Description:

Recent years have witnessed a strong impulse in adopting M-MIMO in wireless networks. Despite the wide research related to M-MIMO for terrestrial networks, much less attention has been devoted to its possible exploitation in the forward link of satellite systems. 

The present invention is related to the design of very high efficient telecom satellite payload combining flexibility and high throughput. In particular, the invention discloses a methodology to optimize and design the active antenna and associated payload to approach the performance of state-of-the-art Massive MIMO solutions with affordable complexity at payload and system level. In particular, the proposed solution avoids the need for communication channel state estimation from the users as required by M-MIMO and on-board complex processing (like matrix inversion or time variant complex digital beam forming). Instead, the proposed approach simply relies on users’ approximate (i.e. km accuracy) location position knowledge. Furthermore, the on-board processing is limited to a digital processor with a switch able to select the most suitable serving beam from a fixed beam grid. The latter is generated by an efficient Fast-Fourier Transform-based digital beam-forming network. At system level, a novel radio resource management (RRM) technique able to avoid worst-case interference scenario has been devised and shown to greatly increase the performance of the proposed pragmatic M-MIMO solution. Through extensive computer simulations the pragmatic M-MIMO performance are shown to be only slightly below to ideal M-MIMO exploiting Minimum Mean Square Error (MMSE) precoding with ideal channel estimation. In practice, this performance is not achievable, thus remaining a purely theoretical benchmark while the proposed pragmatic M-MIMO approach is readily feasible. 

In addition, it is shown that the proposed design methodology and payload architecture can be adapted as a particular case for a more conventional colour frequency reuse scheme associated to an active antenna. In this case, the optimized design allows to greatly increase the system throughput and get performance not very distant from the more complex pragmatic M-MIMO solution.  

The most important features of the invention can be described under the following two groups: 

GROUP 1 – Pragmatic Massive MIMO Solution for Broadband Satellite Communication:

-        Pragmatic approach to implement Massive-Multiple Input Multiple Output (M-MIMO) in satellite telecommunication systems.

-        Novel Radio Resource Management technique for M-MIMO.

-        M-MIMO Direct Radiating Antenna (DRA) optimization methodology.

-        DRA payload optimized architecture for pragmatic M-MIMO.

GROUP 2 – Approaching Pragmatic M-MIMO with optimized Color Frequency Reuse (CFR) DRA design:

-        Color Frequency Reuse DRA optimization methodology approaching M-MIMO.

-        DRA payload optimized architecture for optimized CFR.

Innovations and advantages:

• M-MIMO performance have been shown to be well approximated by a feasible pragmatic approach compatible with an efficient satellite payload design and without the need for Channel State Information.
• It has been shown that using conventional 4C FR and optimized DRA design can bring performance close to the pragmatic M-MIMO.
• The proposed method allows to approach optimum M-MIMO performance with affordable system and payload complexity, without requiring users’ feedback (except for a raw estimate of their geographical location).

Domain of application:

The invention can be used for satellite telecommunication programs with possible spin-off in terrestrial wireless systems (5G and beyond). It is relevant to the payload, active antenna and radio resource management of the satellite telecom system.

In addition, fixed point to multipoint terrestrial links may benefit from the invention.

An evolution of this invention has been developed and it relates to a method to drastically simplify the NP-hard Mixed Integer Quadratic Programming (MIQP) RRM algorithm, whilst being very robust to non uniform traffic different distributions. Please, refer to the following link for further information: PAT 783: Heuristic Radio Resource Management for Massive MIMO in Broadband Communication Satellites. 

For additional information, please refer to the following paper published in IEEE by the inventors:

A Pragmatic Approach to Massive MIMO for Broadband Communication Satellites

Authors: Piero Angeletti, Riccardo de Gaudenzi.