Block Spread IFDMA: An Improved Uplink Transmission Scheme

In this paper, a block-spread interleaved frequency division multiple access (BS-IFDMA) scheme is proposed. It is capable of allocating users in block-level code-spreading process for multiple access on top of the IFDMA multiple access scheme for better user allocation. Orthogonality among users in block spreading is achieved when the block spreading, carried out in the time domain, is over a few IFDMA block symbols with negligible channel variation (i.e. transmission over quasi time-invariant channel). Given the same number of supported users and same system bandwidth, by allocating more users in the block level code spreading domain, more frequency diversity can be achieved for the proposed scheme since more subcarriers can be allocated to individual user in the frequency domain compared to the conventional IFDMA scheme.