Ultra Dense Network or UDN

Cellular network as we know is composed of a large number of cells with each cell serving the small geographical area. Each cell has at-least one fixed base station transceiver (in conventional set-up). One such cellular network with hexagonal cells is shown in Figure 1. In today's era the network cells are becoming more tightly packed and the network is becoming ultra-dense. This is happening due to immense traffic that is generated over the network, which in turn causes lot of chaos over the network. UDN is one of the leading ideas that can be helpful in eliminating the congestion problems of cellular network. By using UDN the voice or data can be easily transmitted to a point from which it can be distributed over network with better speed and efficiency.

Conventional cellular network used tree architecture, where network cells are controlled by Base Station (BS) Managers as shown in Figure 1. Base Station is responsible for managing all voice and data transmission due to which 85% of the total energy is consumed by them in the cell.

Figure 1: Conventional cellular network

The idea is to get access to the available mobile stations as close as possible to the base stations. It can only be achieved by dense deployment of small cells in a high traffic network. In UDN access points or base stations are on every lamp post or in other words very-very close to mobile stations. So it can be said that UDN is composed of very small cells deployed over various outdoors like buildings, stores, airports, university campuses etc. This will also help in reusing the spectrum in a better way. Figure 2 is the simple illustration of UDN.

Figure 2: UDN

It is expected that UDN will cover indoor and outdoor areas with data rates of 100Mbps by 2030. UDN will play a very important role in deployment of next generation cellular network - 5G and beyond. Here are some of the important design consideration for UDN.

1. Total Cost of Ownership (TCO)
   The main consideration will be to minimize the acquisition and deployment cost. All the sites should be able to provide all-in-one installation which will be helpful to reduce unnecessary cost on different networks. Deployment can be reduced by standardized site designs.
2. Operational Impact
   In country as big as India there may be more than 1,00,000 cells to manage in UDN. Therefore it is required to redesign the network and manage this complex environment by shifting from reactive (break then fix) to proactive (health checking) networking.
3. Energy Requirements
   Energy consumption in UDN could be optimized by increasing the number of small cells or by shutting down 10% carriers. Use of modern low power equipment would be required to provide more efficient energy consumption.
4. Dense Network and Radio Network
   As network becomes denser, cloud-based radio network will be helpful in optimizing the network and simplification. It will reduce site and traffic routing costs, while assuring consistency regardless of access points.

By: Ms. Abha Sharma - Assistant Professor (CSE), Chitkara University, H.P.

References

1. Nokia Ultra Dense Network(UDN) White Paper
2. Nokia The evolution of Ultra-Dense Networks
3. https://www.slideshare.net/TechUK/itsf-2015-keynote-evolution-of-the-interconnected-network
4. networks.nokia.com
5. researchgate.net
6. https://www.semanticscholar.org