Overview
Massive-MIMO Technology
The capacity of traditional single-user wireless systems is exclusively limited by the available spectrum and transmission power. Recent developments in information theory, however, have shown that such capacity limitations can be overcome by improving the spatial reuse efficiency through multi-user multiple-input multiple-output (MU-MIMO) technology, or its special form called multi-user beamforming (MUBF). With MUBF, a base station employs multiple antennas to simultaneously send independent data streams to multiple users, tremendously increasing the aggregated network capacity. As MUBF theory dictates, the more antennas a base station has, the more users it can serve simultaneously. Encouragingly, this means that with enough base station antennas, the network capacity can be scalably grow to accomodate more users. This naturally motivates us to put as many antennas as possible on the base station to meet the increasing capacity demand from more and more users.
Argos
To practically implement MUBF theory and realize its capacity benefit, one must address a set of challenges. The Argos project, started in 2011, developed new techniques that enabled hundreds of antennas to be deployed on base stations, resulting in enormous network capacity gains. It used the WARP platform to build the first real-world prototype of a many-antenna MUBF base station and experimentally evaluate its performance. Argos demonstrated the feasibility of many-antenna base stations, and motivated industry adoption of this promising technology in the near future.
ArgosV3
ArgosV3 is a clean-slate design of Argos massive-MIMO base station, providing 1) extreme scalability, 2) maximum reconfigurability, and 3) at-scale deployability. To provide all these features, ArgosV3 leverages the commercial-off-the-shelf Iris SDR modules, designed and manufactured by Skylark Wireless, a Rice spin-off startup company. Iris SDR radios are capable of forming daisy-chains in a cable-less fashion, with up to 10 Iris modules operating seamlessly as if they are a single many-antenna device. Iris SDR modules use an interchangeable high-power front-end modules for UHF, BRS and CBRS bands with maximum output power of 28 dBm, enabling long-range at-scale communication. Multiple daisy-chains of Iris modules are interconnected to a central Hub, which provides data aggregation, time and frequency synchronization and power to Iris daisy-chains. ArgosV3 provides 40Gbps backhaul fiber connection. All these elements are integrated in a weather-proof enclosure, providing an easy-to-deploy plug and play solution. The ArgosV3 design was further developed and currently commercialized as Faros by Skylark Wireless.
ArgosNet
ArgosNet consists of three 96-antenna and a single 64-antenna ArgosV3 base stations deployed on Rice campus. There are five carefully planned designated sites allowing movement of these four base stations for various experiments. Each base station support 40Gbps single-mode fiber backhaul (4x 10 Gbps) to ArgosNet datacenter resources. The datacenter resources currently consists of 6x 36-core super micro servers and an FPGA board which is used for centralized data aggregation as well as multi-cell time and frequency synchronization. These resources are growing over time, with the goal of performing much of the baseband processing in the datacenter rather than at the base stations.
RENEW
RENEW strives to build reconfigurable and open-source software stacks for massive-MIMO wireless, primarily on Faros base stations. This manual documents all the aspect of the software developed by RENEW team from high-level architecture to code details and serves as a tutorial to conduct massive-MIMO experiments on open platforms such as POWDER. This resource will be edited and augmented as more code is released. Throughout this documentation, source code on RENEW gitlab is referenced for better readability.