Tuesday, April 30, 2013

Development of small cells

Each wireless network is built out using many macro cell base stations, each covering a diameter of up to 3 kilometers and carefully located to minimize radio signal interference.  But the disadvantage of this topology is that coverage is not 100 percent. In order to increase the coverage small cells came into existence. The HetNet topology builds a network that includes existing macro cells and complements them with millions of smaller base stations, including micro cells and pico cells, appearing on lamp posts in urban areas and femto cells appearing in homes, residential high-rise apartments and businesses. The small cells provide a very efficient way to offload high traffic areas from the macro cells and therefore increase cell capacity and optimize spectrum utilization.
Today capacity, coverage and QoE expectations of the user has increased manifold. We need HetNet (heterogeneous networks) rather than macro-only networks to cope up with this growing demand. HetNet is a combination of wireless technologies and radio access options to cost effectively deliver higher throughput.  The key component of HetNet is small cells. Small cells are deployable anywhere both indoors and outdoors. Small cells solution is available for single home subscribers. Home subscribers experience better voice quality with no dropped calls due to dead zones, faster, more reliable data connections and higher data throughput. Small cell solutions are available for the enterprises, which helps extends better customer experience to the businesses. Small cells provide coverage and capacity for urban and rural hotspots. Small cells come with integrated Wi-Fi access points as well.
Small cells boost network capacity. If we move base station near to the UE the throughput and the reliability of the data connection will increase dramatically. Small cells have a flat IP architecture which helps us deliver a much better customer experience with low latency and higher speed. Small cells offer a cost effective solution to increase the coverage and capacity demands. Small cells offload traffic from the macro network which helps in increasing the network capacity without the deployment of new macro sites.
While there is extensive hype in the industry about “multi radio access technology (RAT), multi-vendor” type of HetNet solutions, the more imminent and practical solution is the interference avoidance required when small cells are rapidly added to existing LTE Macro centric networks. In order to resolve the interference problem 3gpp introduced inter cell interference control (ICIC) in Release 8 and more recently, in Release 10, the enhanced ICIC (eICIC) .
The SON standard is defined by the 3GPP and specifies algorithms to enhance the planning, deployment, operation and optimization of the network. Based on this standard, a SON algorithm will run upon startup of the small cells, allowing the device to insert itself into the network without interference. In terms of interference management, 3GPP introduced inter cell interference control (ICIC) in Release 8 and more recently, in Release 10, the enhanced ICIC (eICIC) standards. These standards are specified to mitigate interference in neighboring cells by using the power and frequency domains in the case of ICIC and adding the time domain for eICIC. Both standards rely on the X2 interface to exchange information between eNode B’s and typically require a client/server or hybrid deployment in order to perform the optimization and coordination functions.

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