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Lately there has been a lot of buzz around 5G. Last week Prime Minister Narendra Modi inaugurated the country’s first indigenous test bed to help support the ecosystem around 5G. Earlier this year, the Government reiterated its plans to conduct auctions for 5G spectrum in June and expected services to be rolled out by the third quarter of the year.
Service providers have been conducting 5G trials and 5G ready phones have been flooding the market. But what exactly is 5G? What lies behind the promise of faster downloads and better call quality?
Radio electronics refers to a broad range of technologies that can transmit, receive and process wireless signals. While these technologies can utilise electromagnetic spectrum that goes all the way up to 300GHz, the lower frequencies of this spectrum are particularly attractive. Lower frequency signals can travel longer distances and penetrate obstacles with lesser attenuation. Electronic components (amplifiers, transmitters, receivers) operating at lower frequencies are also easier to design and manufacture. Consequently, much of the bandwidth in the lower frequencies of this spectrum has already been allocated for several applications (mobile communications currently use the spectrum from 800MHz to 2.5 GHz).
New spectrum at 3GHz and beyond
With the increasing demand for mobile services, the currently allocated spectrum is proving inadequate. At the simplest level, 5G represents the allocation of new spectrum to increase capacity. Since most of the spectrum at lower frequencies is already being utilised — much of this new spectrum is being allocated at higher frequencies. The first deployments in India will be around 3GHz, but will expand to 25 GHz and beyond.
As 5G services evolve to occupy higher frequencies, it will significantly increase the bandwidth available for mobile services. However, at these frequencies the design of the transmitting and receiving equipment becomes more complex. Signal attenuation also increases. So, the coverage area of each cell tower will decrease which will require the towers to be more closely spaced.
An interesting fact related to the physics of signal transmission is that at higher frequencies it becomes easier to direct a signal in specific direction. So, signals transmitted from a cell tower can be more precisely directed at a specific user (rather than spreading out in various directions which is just a waste of energy).
Intuitively, this enhanced directivity results in less interference between signals meant for different users which directly translates to increased capacity. Thus, while operating at higher frequencies has some fundamental challenges, it offers some unique opportunities as well.
Evolving communication needs
Since much of the 5G infrastructure is being built from ground up, there is a chance to redesign the technology to make it more suitable for the evolving communication needs of the future. 5G places special emphasis on low latency, energy efficiency and standardisation.
Existing wireless communication infrastructure is primarily designed around the needs of mobile phones. However, several emerging applications in factory automation, gaming and remote healthcare have more stringent latency requirements. Self-driving cars is an illustrative example. Low delays between transmission and reception of messages are extremely critical when these cars have to co-operate with each other to avoid accidents.
As 5G rolls out, over the next several years the volume of data is expected to exponentially increase. To ensure that there isn’t a corresponding increase in the energy usage, 5G places a lot of importance on energy efficiency. This will mean lower energy bills for service providers and longer battery life for mobile devices.
Greater attention to standardisation is another important aspect of 5G. Today most of the components that make up wireless telecom interact with each other using proprietary protocols that are vendor specific. To enable the rapid deployment of 5G infrastructure there is an industry-wide effort to standardise interaction between components. Greater standardisation would enable service providers to build their infrastructure, ‘mixing and matching’ components from multiple vendors. Switching vendors would also be easier which would foster competition and lower costs.
Advanced R&D
There is a lot of research in both industry and academia centred around 5G. An interesting topic is the convergence of positioning, sensing and communication. Traditionally, positioning, sensing and communication have been seen as separate technologies (for e.g., GPS is used for positioning, and radar for sensing). However, all three technologies involve transmission and reception of radio signals — hence it is possible for positioning and sensing to piggy back on 5G infrastructure that is primarily meant for communication. While this is not a new concept, 5G is expected to significantly improve the state of art. It turns out that some of the key features of 5G (such as increased bandwidth availability and antenna directionality) are also useful for improved accuracy of positioning and sensing.
There is also a lot of research around cost and energy efficient electronic devices that can transmit and receive high frequency signals. This involves delving into the fundamental physics of semiconductor technologies and is expected to lay the foundation for the growth of wireless technology into higher frequency bands.
In fact, engineers are already busy prototyping a 6G system which would utilise the large amounts of available spectrum at frequencies above 100 GHz. As one of my colleagues who works in this domain pointed out — engineers are perhaps having more fun developing these technologies than consumers are using them!
Sandeep Rao is with Texas Instruments
