Distributed Massive MIMO for LEO Satellite Networks

Abstract

The ultra-dense deployment of interconnected satellites will characterize future low Earth orbit (LEO) mega-constellations. Exploiting this towards a more efficient satellite network (SatNet), this paper proposes a novel LEO SatNet architecture based on distributed massive multiple-input multiple-output (DM-MIMO) technology allowing ground user terminals to be connected to a cluster of satellites. To this end, we investigate various aspects of DM-MIMO-based satellite network design, the benefits of using this architecture, the associated challenges, and the potential solutions. In addition, we propose a distributed joint power allocation and handover management (D-JPAHM) technique that jointly optimizes the power allocation and handover management processes in a cross-layer manner. This framework aims to maximize the network throughput and minimize the handover rate while considering the quality-of-service (QoS) demands of user terminals and the power capabilities of the satellites. Moreover, we devise an artificial intelligence (AI)-based solution to efficiently implement the proposed D-JPAHM framework in a manner suitable for real-time operation and the dynamic SatNet environment. To the best of our knowledge, this is the first work to introduce and study DM-MIMO technology in LEO SatNets. Extensive simulation results reveal the superiority of the proposed architecture and solutions compared to conventional approaches in the literature.

Satellite Swarm-Based Antenna Arrays for 6G Direct-to-Cell Connectivity

“…Another interesting work on deep-space communication is [27] which shows a distributed swarm array composed of CubeSats able to provide coherent communication in the Ka/X band. Recent publications have studied the use of multi-satellite configurations to provide direct connectivity to Earth, but consider a higher frequency, a lower number of more powerful satellites equipped with single [28] or multiple antennas [29], [30], and considering higher performing UE. Although not related to the swarm, the work in [31] analyzes the direct connectivity from NGSO Satellites to 5G devices in millimeter waves (28 and 39 GHz).…”

Broadband Connectivity for Handheld Devices via LEO Satellites: Is Distributed Massive MIMO the Answer?

“…CF-mMIMO shows great potential to substantially improve network performance (e.g., spectral efficiency and power efficiency) [28]. Utilizing this technology, our previous work in [29], [30] proposed a distributed massive MIMO (DM-MIMO)-based LEO satellite architecture exploiting the opportunities in the new LEO satellite constellations. This architecture could be used to support broadband connectivity for unmodified handheld devices in LEO satellite networks.…”

“…In addition, SSNs coordinate to handover UTs between clusters to keep the connectivitng of UTs to the network with minimal service interruptions. The concept of cluster handover in DM-MIMO-based LEO satellite networks is discussed in [29], [30]. We suppose that the transmission protocol is time division duplexing (TDD).…”

“…Serving UTs with a subset of cluster SAPs is the main idea of user-centric CF-mMIMO as discussed in [38]. This has been implicitly adopted in [30] by setting the power control coefficient of non-serving SAPs to zero. Moreover, the control signalling between SAPs and the SSN can be minimized by allowing some functions to be processed locally at SAPs, e.g., using conjugate beamforming techniques with locallyestimated channels and precoding matrices.…”

“…This work was supported by the High Throughput and Secure Networks Challenge Program (CSTIP Grant #CH-HTSN-625) at the National Research Council of Canada, as well as MDA and Mitacs. Accordingly, compensating from (67) into (65) gives (30).…”