Advantages of Cell-Free Massive MIMO | Disadvantages of Cell-Free Massive MIMO
This page covers advantages and disadvantages of Cell-Free Massive MIMO architecture. It mentions benefits or advantages of Cell-Free Massive MIMO and drawbacks or disadvantages of Cell-Free Massive MIMO.
Introduction: In traditional cellular network, each area is divided into regions i.e. cells. BSs (Base Stations) are deployed in each of these cells. All the BSs are connected using backhaul.
BSs are interfaced as per various configurations such as star, mesh etc. They are interfaced with PSTN (Public Switched Telephone Network) , MSCs (Mobile Switching Centres) and PSDN (Public Switched Data Network) in the backhaul. The common cellular networks are GSM, CDMA, LTE, 5G etc. Refer Pros and Cons of Cellular Network and Cellular Communication tutotial >>.
Cell-Free Massive MIMO Architecture
The figure-1 depicts Cell Free Massive MIMO Architecture and traditional cellular network. As shown, Cell-Free Massive MIMO consists of Access Points (APs) and central processor connected by fronthaul. APs are deployed which are scattered over the coverage area. Each of the APs are connected using fronthaul i.e. wires to a central processing unit. The central processor controls all the APs. All the APs serve all the surrounding users and there are no cell boundaries as in cellular network. Hence the name "cell-free" for such network architecture.
In this architecture, many antennas are distributed geographically instead of co-location in BS (Base Station). These antennas are known as APs (Access Points). These APs operate jointly to serve subscribers in same time/frequency resources. APs work together synchronously and coherently. APs function as a massive MIMO BS which are coordinated by one or more Central processors using fronthaul network.
Following five features make Cell-Free Massive MIMO favourable over CoMP (Coordinated Multipoint) in 5G beyond future
technologies such as 6G.
• Massive MIMO baseline operation
• User centric perspective
• Predictable performance
• Integration with mmwave
• Cost effective
Benefits or advantages of Cell-Free Massive MIMO
Following are the benefits or advantages of Cell-Free Massive MIMO:
➨It offers macro diversity gain due to aggressive deployment densification. APs are available closer to users which leads to reduced path loss and shadowing effects. Reliability of link is improved as each user is served by many APs and there is less probability of blockage.
➨There is reduction in inter-cell interference. Hence it outperforms small cell networks.
➨It delivers more uniform QoS (Quality of Service) among users due to its user centric implementation.
➨It provides beamforming and spatial multiplexing gain.
➨Cell-free massive MIMO combines three technologies viz. ultra-densification, mmwave and massive MIMO. This results into higher throughput.
Drawbacks or disadvantages of Cell-Free Massive MIMO
Like all the technologies, there are drawbacks or disadvantages of Cell-Free Massive MIMO
which can be overcome by further research in the respective areas.
➨The architecture requires widespread and expensive hardware.
➨It requires accurate synchronization and coordination among the APs.
➨It requires simple but effective resource allocation schemes to minimize signalling overhead.
➨It is not scalable system in its canonical form.
➨It is difficult to finalize whether the task to be implemented in distributed manner or in centralized manner.