Data security has become a serious issue with the advancement in communication technology. Data Security is considered as the primary factor for every communication system. There are many ways available to provide security data that is being communicated. Here we discuss about various types of algorithms which provides effective security for data communication.


AES algorithm stands for Advanced Encryption Standard algorithm. This algorithm has low complexity and high security level so it has been used for many purposes. Encryption process converts data to a coded form called cipher text. Then decryption process converts it into original form called plain text. It converts plain text in blocks of 128 bits to cipher text which means coded message using keys of 128, 192 and 256 bits. AES design consists of three block ciphers like AES-128, AES-192 and AES-256. AES-128 uses 128 bit key length to encrypt and decrypt a block of messages likewise AES-192 uses 192 bit key length text and AES- 256 uses 256 bit key length message. Symmetric stands for secret key and cipher uses same key for encryption and decryption of text. Usually there are 10 rounds, 12 rounds, 14 rounds for 128-bit keys, 192-bit keys and for 256-bit keys respectively. It consists of several processing steps like substitution, transposition and mixing of the input plaintext to transform it into the final output of ciphertext.


TDMA algorithm means Time-division multiple access algorithm which is a channel access method for shared medium networks. Here same frequency channel is shared by several users by dividing the signal which increases data carrying capacity. There is implementation of RF communication in swarm robots by this algorithm. The term swarm stands for network of interconnected robots working together to achieve common goals. This require fast and reliable communication that uses high frequency radio communication. So that this algorithm is used in it.


Novel throughput maximization algorithm (TMA) is developed mainly for adaptive FSO-radio frequency communication system which is proposed to solve individual channel issues. This system is basically to overcome issues of weather conditions and adjust the current demand of new broadband channels. This algorithm for adaptive hybrid communication system is being analyzed by LDPC (low density parity check) code under various weather conditions. This algorithm (TMA) is developed for the hybrid FSO/RF communication system considering both regular and irregular structure of LDPC code. This idea is mainly to optimize the bit fraction and trying to exploit that channel, which have clear sky conditions. While performing this optimization, the proposed algorithm considers two cases:-partially optimized and fully optimized. The output shows that this algorithm gives a performance gain of 2.25 dB under various weather conditions.