2D PARITY CHECK PROGRAM C SERIAL

When the reciever get the data, it calculate the checksum value from the received data and compares the calculated value with the received checksum value.ĭefinately it looks more complicated than Parity Algorithm, but it is more robust in finding errors. In Checksum algorithm, we calculate a special number called 'checksum' value from the original data and add the checksum data to the transmitted data. The only difference is that in this algorithm we convert the data into a 2 dimensional array and apply parity bits horizontal and vertical direction as illustrated below. The concept and method of Two Dimensional Parity check is almost the same as the simple parity check explained above. (Try think of those cases where this algorithm fails) Even for detection, there are many cases where this algorithm fail to detect errors. But this is detection only algorithm and it cannot correct error.

2D PARITY CHECK PROGRAM C SERIAL

This is very simple and still being used in some simple data communication like RS 232 Serial communication. Following is the example process for 'Even Parity' algorithm. In Parity Check method, transmitter reorganize the original data so that the total number of '1' is only Even (Even Parity) or only Odd (Odd Parity). If you convert data into binary stream and count the number of '1' in the data, it would be only one of two cases. In this section, I will briefly explain about several most common methods for step i) and iv), v) that are used for data communication. When we talk about Error Detection or Correction (step v), we normally explain about step i) as well because the error detection/correction methods varies depending on step i). V) If errors are found in step iv), ask for retransmission (ARQ case) or try to recover(fix) the error (FEC or HARQ case). This is called Error Detection and happens in the reciever side. Iv) Check if there is any error in the received data. I) Convert (organize) the original data into a special structure in such a way that the reciever can easily detect the error. For this detection/correction, method we need to go through roughly following procedures. The only thing you can do for those errors is to come out with the various methods of detecting and fixing those errors. Whatever you do, there is no way to prevent any error. Definition of Error Correction is to fixing the error bit (data) to normal bit (data). What is Error Correction ? The definition is simple. This is why the first type of mechanism is still being used in many applications. But in most cases, this second type tend to be more complicated to be implemented or requires more overhead for data transfer.

Of course, the second type is better in most case since it will give a chance for error recovery.

A mechanism that tells on both the existence of error and the location of errors.

A mechanism that tells on the existence of error, but does not tells on the location of errors.

There are roughly two types of Error Detection as follows. This is why Error detection is not so simple. So we have to figure out the location of errors only from the received data. However in realty, we don't know what is the transmitted data (original data). Just simply by comparing the transmitted dataĪnd received data, we can easily find the location of errors. If we know the exact contents of transmitted data, it would be very simple to find out the location of errors.

This mechanism of finding the existence of error is called 'Error Detection'. Once Error happened, we need to have some mechanism to figure out 'whether there exists any error' or 'exactly where is the error occured'. In case of data storage, you can define Error as 'any difference between the data being sent for writing and the data really written on a media (e.g, Hard Disk, Memory This may sound specific only to communication. Error can be defined as 'any difference between the transmitted data and received data'. What is done if the reciever find the error ?įirst let's think of the definition of 'Error'.You would realize that most of digital data processing or communication would have not be realized if there is no mechism for error handling (error detection and correction)įollowings are the topics that will be dealt in this page. Most of Wireless Communication (e.g, Mobile Communication like WCDMA, LTE etc).Data Storage and read on Memory, Harddisk, CD etc.Several common examples of the case where some form of error handling is used are as follows : Actually in almost every data processing and communications error handling is one of the most critical part of the process. There are many cases where we have to seriously consider 'Error'.

2d parity check program c