An Emerging Concatenated Multitone Air Interface for High Speed Access and Home Wireless Networks

This paper presents further enhancements to a recently proposed air interface that concatenates an inner filtered multitone (FMT) modulator with transmission over multiple antennas, and an outer space-time cyclically prefixed discrete multitone (ST-CP- DMT) modulator with frequency domain data spreading. We focus on the uplink with asynchronous mobile devices. The contribution is threefold. Firstly, we show an efficient implementation of the transmitter. Secondly, we propose an efficient multiuser receiver architecture that requires a single polyphase filter bank and a concatenation of DFTs. Thirdly, we analyze time domain pre- equalization (TEQ) to shorten the equivalent channel impulse response between the FMT filter bank output and the ST-CP-DMT receiver. The proposed multiuser receiver outperforms the bank of synchronous single user receivers yet requiring less complexity. TEQ has the potentiality of improving performance in severely dispersive channels, and to increase transmission rate since the DMT stage can use shorter cyclic prefix (CP).