On the use of notch filters and ordered co-channel TDMA slots strategies to the TDMA and CDMA overlaid systems

CDMA and TDMA overlay has been investigated as a way to take advantage of the bandwidth available in narrowband systems. It has been demonstrated that without notch filters and ordered co-channel TDMA slots strategies, CDMA and TDMA coexistence cannot be achieved in practical situations. The use of notch filtering rejects only part of the intracell interference generated from the TDMA system but the ordered co-channel TDMA slots strategies decrease the intercell interference which could not be rejected by the filters. We have considered that the two systems share the same frequency bandwidth and power control on both layers. The performance of the overlaid system has been analyzed in the CDMA and TDMA layers in terms of blocking probability and outage probability.