Changes

CDMA is being accepted as a third generation (3G) system and a specific feature of 3G system systems is that it offers they offer a radio interface adapted for all kinds of services and combination of services(such as data,voice,image video etc). The big issue challenge is of multiplexing of these services which have do not have the same demands in terms of quality of service(QoS) which can be represented as BER(bit error rate),processing delay,frame error rate etc. Different QoS will require different channel encoding and interleaving strategies. The demand of BER can be satisfied when the coding bits have atleast at least a code dependent ratio Eb/I(ratio of bit energy to interference). There are several influences that might change system performance(BER) and hence Eb/I ratio, of which the most effective is variation of Bit Rate by a step of '''Rate Matching'''. <br><br> 

The patent '''EP 1385290 [[Media:EP1385290.pdf EP1385290]] titled "Method for balancing Eb/I ratio in a service multiplexing CDMA system and a telecommunication system using this method"''' targets at this concept of Rate matching and introduces an algorithm of calculating effective data output bits by a process of repetition or puncturing of the input bits governed by a '''rate matching ratio''' and '''puncturing ratio''' received from the sending entity(can be BS or MS). The following framework highlights the various steps involved in providing variable QoS. The received data from the transport block is classified into different processes based on their QoS. Data is split onto various transport channels to which a CRC code is attached for error correction. Further all these transport channels are multiplexed on one line by concatenation, interleaved, segmented and then rate matched. The rate matching step is performed using the rate matching ratio and puncturing ratio which is received from the sending entity.(an exchange of handshaking signals is occuring).[[Media:Patent.pdf]]