Research Of Key Technologies On Multicarrier IDMA

Multi-carrier Interleave Division Multiple Access (IDMA) is a kind of Hybrid Multiple Access (HMA) technology, which combines multi-carrier technology with IDMA. Compared with other pure multiple access technology like Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Code Division Multiple Access (CDMA) and plain IDMA.By adopting the two-layer hierarchy, multi-carrier IDMA becomes a promising candidate multiple access scheme for 5G due to the inherent advantages of each layer.First of all, based on the conventional IDMA system, this thesis provides an idea of using ’full’ spreader to spread the bit sequence to enhance diversity collection. In addition, a new signal detection method based on continuous signal modeling is also employed. Simulations show that the proposed idea improves the performance of conventional IDMA.Then, HMA systems including OFDM-IDMA and FBMC-IDMA are investigated with the goal of achieving better bit error rate (BER) performance and making the most usage of the frequency spectrum.For OFDM-IDMA system, a revised subcarrier power allocation algorithm based on the traditional ’waterfilling’ algorithm is proposed. Using the revised method, the instantaneous transmitting power can be dynamically allocated for all subcarrier for each user and the BER performance is expected better than using the equal power allocation method. This is verified by simulations.For FBMC-IDMA system, at the receiver side, Analysis Filter Bank (AFB) and Feed Back (FB) modules are removed and direct yet modified IDMA iterative soft-cancellation module is proposed instead. From simulation results, we can see that, under the same conditions, the proposed FBMC-IDMA system can obtain better performance than OFDM-IDMA system. Morever, this thesis also provides a subcarrier allocation method. Using this method, all users can select several subcarriers for information transmission in a dynamic and parallel mode, which improves the system BER performance and spectrum efficiency.