How to overcome high latency in the 5G era?

May 11, 2020 //By Robert Barnes
latency
From video conferencing to multiplayer online gaming, all of us will have experienced latency issues at some point. But this isn’t a new phenomenon that’s tied to the unique circumstances in which many find themselves today. It is a challenge that goes to the heart of how communications technologies work.

Low latency is a challenge to be overcome in the 5G era

Higher latency or “ping time” means that in Fortnite you’ll find yourself “killed” before you’ve ever seen your opponent; in a game of FIFA, you’ve conceded a goal before you’ve seen the ball kicked. High latency renders games unplayable, causes people to talk over each other in video conferences, and risks killing the market for consumer applications such as Virtual and Augmented reality (VR and AR) that many hope will be major 5G revenue opportunities but are highly latency sensitive.

In the standards for 5G many innovations have been included with the target of reducing latency by 10 or 20 times compared to 4G. The degree to which these are delivered on will in a large part come down to whether we, as an industry, let latency get in the way of a supercharged future.

 

Channel coding as a latency challenge

As mobile devices of all shapes, sizes and form factors communicate with fixed infrastructure, wireless communications are susceptible to noise and interference. If uncorrected this will lead to the received message differing to the transmitted message and therefore requesting a retransmit.

To address this, before sending a message, transmitters use a channel encoder to protect the communication from these transmission errors by adding additional bits, which enable the receiver decoding the transmitted signal to recompile the message correctly, a process sometimes called forward error correction.

Different types of channel codes exist, each coming with its own benefits and challenges. For 5G, Low Density Parity Check (LDPC) coding has been chosen for the data channel, where the user’s information is transmitted, and Polar Coding has been chosen for the control channel, where the mobile and the base station exchange control information.


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