How to tackle indoor telecom connectivity challenges?

By Deepak JRP

India is geographically a large country with varied landscapes. From the mighty Himalayas to the thick forests of western Ghats, it offers myriad challenges for deployment of cellular technology. The deployment of wireless technologies for cellular communication has seen exponential growth with wide spread adoption by the customers. Telecom operators are now able to reach remote parts of India where laying of the traditional copper lines has been a big challenge owning to the cost and the geographical terrain.

The cellular technology has its advantages and pitfalls. With the exponential growth comes the challenges of providing a reliable and efficient services to the customers. The common issues plaguing the wireless customers include call drops, garbled voice calls, slow internet speeds, internet timeouts and increased battery usage. These issues are more significant indoors than outdoor environments due to the very nature of our structures and geographical terrain.

Typically, in a cellular technology deployment, we have the base station or the cell towers radiating the cellular signals around it, referred to as cells. The mobile phone picks up these signals and they are transmitted back and forth completing the wireless circuit. A weak signal at any given location can be attributed to multiple causes. The signal strength varies as per the distance from the cell tower from a phenomena termed as free space path loss. Effectively, users at the cell edge usually have to deal with lower signal strength, which forces the mobile phone to radiate at higher power levels. This reduces the battery life as the device has to now radiate at increased power levels to be able to communicate with the base station. This increase in power can pose a potential health hazard to the users. Obstructions in the form of hills, thick foliage, tall buildings, etc., add to the degradation of the cellular signal strength.

Construction material used and the thickness of the structures, proves a major challenge in signal propagation for optimal indoors reception. Historically, Indians have been using traditional materials for constructions like mud, lime mortar, bricks, stones for walls, metal frames, etc. The usage of concrete or mud walls with thickness up to 12 inches pose a major barrier for the penetration of the cellular signals indoor. Radio waves are severely attenuated by these and the signal strength reaching indoors is drastically reduced. Metal frames and structures reflects or absorbs the cell signals, thereby reducing the cellular signal strength. Lower frequency RF signals offer some consolation to these issues as they have better in-building penetration characteristics i.e., they can pass through walls with lesser attenuation. So, a cellular service on the 900MHz offers a better signal strength indoors than the 1800MHz.

Dense urban areas reflect the cellular signals creating a multipath effect. The reflections reach the mobile phone at different time intervals due to the longer propagation effects. In addition to these, effects of co-channel interference and pilot pollution in high rise buildings complicate the situation further. Subscribers in high rise building are faced with this unique problem that they are able to receive weak signals from multiple cell towers. This leads to constant or frequent handover (ping pong hand off) between the cell towers and a very bad user experience by the customer.

The world is poised for a data tsunami and with the advent of 4G and beyond technologies, customers are pampered with a multitude of devices catering to online gaming, connected homes, telemedicine, IoT, IoE, etc., Most of this data is driven from indoors and telecom operators are faced with ever increasing pressure to ensure a seamless cellular signal indoors.

Multiple technological advancements like distributed antenna system, small cells and cellular signal repeaters are used to address the coverage issues both indoors as well as outdoors. Advanced echo cancellation algorithms are used to reduce the multi-path fading effects. RAKE receivers are also used to handle multipath signals. 4G technologies like LTE use inter cell interference co-ordination (ICIC) techniques to restrict the channel interference issues.

Repeaters and small cell devices hold the key in resolving the indoor signal issues. Repeaters are available in multiple form factors like single box solution, multiple box solutions and distributed antenna repeater system (DAS) with varying cost options.

Customer delight and user experience is the key to success for any telecom operator business. With the ever decreasing ARPU, it is imperative to the telecom operators to provide the best service to customers and reduce the churn. Advanced cellular access technologies like 4G LTE and beyond holds good promise towards achieving this. Along with an effective RF planning during deployment, telecom operators are increasingly looking at adopting innovative tools & technologies to balance the network load, eliminate black spots and monitor the real time network characteristics. With the plethora of connected devices and applications available with the customers, it is mandatory for the telecom operators to provide reliable connectivity and coverage options indoors, where most of the traffic is generated. Technological advancements in complimentary areas like cellular repeaters, small cells and DAS along with software tools like SON and SDR will be go a long way in resolving the current issues being faced by the telecom operators.

(The author Deepak J R P is Director, Engineering & Technology at 5BARz India, a start-up headquartered out of San Diego in the US and out of Bengaluru in India. 5BARz has patented technology that goes into its single piece , plug and play network extenders which strengthen weak cellular signals)