Telecommunications, 5G and Shannon Limit

Telecommunication – the transmission of signals over a distance for the purpose of communication. The engineering aspect of telecommunications focuses on the transmission of signals or messages between a sender and a receiver, irrespective of the semantic meaning of the message. The Open Systems Interconnection model (OSI model) is a conceptual model that characterises and standardises the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology.

Such an abstraction allows the functionality provided by layer-N to be defined in terms of Layer-(N-1). Communication protocols enable an entity in one host to interact with a corresponding entity at the same layer in another host. A communication protocol is a system of rules that allow two or more entities of a communications system to transmit information

Information theory and Fundamental Limits: A revolution in wireless communication began in the first decade of the 20th century with the pioneering developments in radio communications by Guglielmo Marconi, including Charles Wheatstone and Samuel Morse (inventors of the telegraph), Alexander Graham Bell (inventor of the telephone), Edwin Armstrong and Lee de Forest (inventors of radio) and many others. Among these inventor stands out Claude Shannon who defined “information”, introduced a simple abstraction of human communication (channel) and showed that “Data” can only be transmitted so within constraints of time and quantity. (the constraints are a dependent on the medium (copper wire, fibre optics, electromagnetic, etc..) ). He came up with a mathematical basis of communication that gave the first systematic framework in which to optimally design telephone systems. The main questions motivating this were how to design telephone systems to carry the maximum amount of information and how to correct for distortions on the lines.

He used Boolean algebra–in which problems are solved by manipulating two symbols, 1 and 0–to establish the theoretical underpinnings of digital circuits that evolved into modern switching theory. All communication lines today are measured in bits per second, which is also used in computer storage needed for pictures, voice streams and other data. He came to be known as the “Father of Information theory”

5G: The 5 generations of wireless technology are as below. 5G makes a big statement with peak theoretical data rates of 20 Gbps for downlink and 10 Gbps for uplink.

  • 1G: Voice only, analog cellular phones Max speed: 2.4 Kbps
  • 2G: Digital phone calls, text messaging and basic data services Max speed: 1 Mbps
  • 3G: Integrated voice, messaging mobile internet, first broadband data for an improved internet experience and use of applications Max speed: 2 Mbps
  • 4G: Voice, messaging, high speed internet and high capacity mobile multimedia, faster mobile broadband Max speed: 1 Gbps
  • 5G: A revolution in user experience, speeds, technology, connecting trillions of devices in the IoT, supporting smart homes, smart buildings and smart cities Max speed: 10 Gbps

However these are numbers as defined in the specifications. The perceived reality w.r.t speeds are lower and a more useful metric defined by the International Telecommunications Union (ITU) for the IMT-2020 standard (basically the 5G standard) is user experience data rate, which is the data rate experienced by users in at least 95% of the locations where the network is deployed for at least 95% of the time.

As cellular communication has progressed in the last two decades, we’ve rapidly approached the theoretical limits for wireless data transmission set by Shannon’s Law. The equation explores the relationship between the total data throughput capacity of a system, in terms of spectrum (radio frequencies), number of antennas and signal to noise ratio on the communication channel.

I have described a few components of 5G in this article. The physical properties of higher frequencies (millimeter Waves: 30 – 300 GHz) conjures up more Space, allowing more data to move across at a given instant. It opens up another decade or 2 of constantly pushing the limits of Shannon’s law and taking us into a new era of technology and experiences. I will try and explore this equation in the context of #5G in my subsequent posts.

5G shots

5G will be the most transformative tech of our lifetime. I will try and explain a few terms to demystify the landscape.

Millimeter Wave: An entirely new section of spectrum never used for mobile services. Millimeter waves are broadcast at frequencies between 30 and 300 gigahertz, compared to the bands below 6 GHz . They are called millimeter waves because they vary in length from 1 to 10 mm, compared to the radio waves that serve today’s smartphones, which measure tens of centimeters in length

Carrier Aggregation: Uses multiple frequency bands together and leverages them together. This means a user can simultaneously be connected (via device) with both 700 Mhz and 1900 MHz frequency of the spectrum and hence can better use all the network resources. Enables increased data speeds (more data to download or upload at a given instant) because there is more space (on the spectrum) for traffic to move around.

256 QAM and 4×4 MIMO: Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. With this approach the carrier is able to pack a lot of more information in the same space without loosing on quality. This leads to speed and efficiency. Combine this with the 4×4 MIMO (multiple inputs multiple outputs) – which provides the ability layer the network (stacking up in another dimension) and also doubles the smart phone antennas – the amount of data that can be carried over at any instant along with the speed multiples many fold.

Full Duplex: With full duplex, a transceiver (within a cellphone) will be able to transmit and receive data at the same time while on the same frequency, doubling the capacity of wireless networks at their most fundamental physical layer

Small Cells: Portable miniature base stations that use very little power to operate and can be placed every 250 meters or so throughout cities. To prevent signals from being dropped, carriers may blanket a city with thousands of small cell stations to form a dense network that acts like a relay team, handing off signals like a baton and routing data to users at any location.

The features and benefits of 5G will evolve over time, with transformative changes coming over the next several years as standards for eMBB, Critical IoT, and Massive IoT use cases are developed by 3GPP. Use cases for 5G fall into three broad categories: enhanced mobile broadband, massive IoT, and critical IoT.

  • Enhanced broadband will provide higher capacity and faster speeds for many of today’s common use cases. This includes fixed wireless access, video surveillance, enhanced experiences in brick-and-mortar retail locations, mobile phones and others.
  • Massive IoT will support the scaling of machine-type communications. This solution will support health monitoring, wearable communication, fleet/asset management, inventory optimization, smart home, health monitoring, wearable communications and more.
  • Critical IoT will enable new use cases that require ultra-reliable, low-latency communications. It is a geographically-targeted solution for smart factories, smart grids, telemedicine, traffic management, remote and autonomous drones and robotics, mobile bio-connectivity, interconnected transport, autonomous vehicles and more.