Spatial coupled LDPC (SC-LDPC) code provides an entirely new way of approaching capacity for communication systems

however

a rate loss caused by additional check nodes during the coupling process. In order to eliminate rate loss

a coupling method was proposed. The edges expansion of the variable node in the first position were unchanged

and the edges of the middle position were connected backwards from the previous position check node

then the edges of the last position were symmetrically distributed with the edges in the first position. Therefore

a rate-loss-free SC-LDPC code was designed without added addition check nodes. Extrinsic information transfer (EXIT) theoretical analysis and bit error rate performance simulation were adopted in the AWGN channel. It is showed the SC-LDPC variant structure is superior to the traditional structure with a shorter coupling chain length

not only can the rate loss be avoided

but also better threshold and decoding performance

it has more advantages in future communication systems.