What is channel coding?

Video 10 - Wireless comms & the need for error correction v2

 

Wireless communication systems depend on channel coding (sometimes called forward error correction) to ensure that the data received is the same as the data sent. Wireless links suffer from interference and fading which causes errors, so to overcome this the transmitter adds additional information before the data is sent. Then at the receiver end, complex codes requiring sophisticated algorithms decode this information and recover the original data.

Using more sophisticated channel codes is key to increasing the performance of wireless systems of the future and this page explains some of the high level benefits:

What challenges does channel coding address?

The primary purpose of channel coding is to increase efficiency, the better the system can correct the inevitable errors introduced by wireless transmission the more efficient it will be. Specific benefits include:

Reduced error rates and retransmission

The Block Error Rate or BLER measures errors that cannot be corrected, un-correctable errors require retransmissions, which introduce latency and lead to poor end user experience.

Increased capacity

As more data is sent across a link noise and interference increase. Better error correction enables the system to tolerate the increased errors created and therefore allows greater capacity – ultimately resulting in lower per user cost.

Increased throughput

Higher performance channel coders and decoders can sustain higher data rates leading to increased throughput.

Reduced power usage

Increasing the efficiency of the wireless link reduces the power requirements at both the base station and the user's device, which in turn leads to increased battery life.

What are the benefits of AccelerCommTM channel coding solutions?

AccelerCommTM channel coding solutions deliver market leading performance at maximum efficiency. We deliver a fully standards compliant solution for Turbo decoder, used in LTE systems, and also Low Density Parity Check (LDPC) and Polar complete chain solutions for 5G New Radio. Our solutions use patented techniques to optimize them to the wireless standard they are designed for, giving significant gains over generic solutions.

For example, as wireless interference conditions change the standard will dictate how the characteristics of the channel coding should be changed by adjusting what is known as the coding rate. The channel coding solution must efficiently meet the requirements across all possible coding rates. A generic decoder may well have to be significantly over specified at some coding rates, whereas the AccelerCommTM solutions are optimized to closely match the profile required by the standard in an efficient way. This efficiency specifically delivers:

  • High quality error correction performance and no error floors
  • Full compliance with all throughput and latency requirements of the standard
  • Reduced area for hardware solutions and processing resources for software solutions
  • Reduced power consumption, heat generation and cost
Turbo codes for LTE URLLC

What are the channel coding challenges for 5G?

3GPP 5G NR takes the requirements for channel coding to a new level. 5G is intended to serve an extremely wide range of use cases, with performance requirements typically at least 10X those delivered by LTE, with throughputs of up to 20Gbps and latencies below 1 millisecond. 5G has several configurations, known as numerologies, to support a very wide range of frequency bands.

5G introduces a variant of Low Density Parity Check or LDPC channel coding, not used in 3GPP standards in the past. Although LDPC has already been used in some WiFi standards, delivering the extreme performance requirements for 5G across the vast range of possible use cases is a whole new challenge.

AccelerComm’s LDPC solutions are designed and optimized for 5G from the outset and are able to deliver fully standards compliant performance with market leading efficiency, requiring less resources and less power than competitive solutions.

A particular focus for the 5G standards is reducing latency, the time between when a block of information is sent and when it is received by the user. Low latency will be key to several new  applications from mobile gaming to industrial automation. These low latency requirements place extreme timing constraints on the channel decoder in particular and AccelerComm’s solutions already meet the requirements for tomorrow’s applications today.

Video 11 - transition to 5g

How do you measure the performance of channel coding?

The performance of a radio link is measured by its signal to noise ratio or SNR. A channel coding solution is primarily measured by its ability to correct errors at a given SNR, but it is also important to understand the maximum possible throughput (the amount of data per second) and the latency (the delay introduced) as well as the resources and power consumed.

Video 11 - Characterising the performance of channel codes  v2

How do you select the right channel coding IP solution?

In some communications systems the channel coding may not be defined in a standard and there may be other factors to consider:

  • Flexibility – designing a wireless communications device is always a matter of optimizing the trade off between many factors to suit the intended use case. AccelerCommTM solutions can be configured so their performance and resource uses are optimized to match the rest of the design.
  • Multiple platforms – different use cases require different implementations. All of our IP is available for use in custom silicon (ASIC) programmable hardware (FPGA) or as software solutions.
  • Supporting features – as well as the core encoding and decoding functions AccelerCommTM IP includes extensive supporting functions to deliver full standards compliance.
  • Ease of integration – our IP can be integrated into your design easily as it uses standard interfaces and comes with a complete suite of test and reference implementations.
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