Hardware realization of UMTS femtocell modem with uplink interference cancellation

In this paper, the hardware realization of UMTS femtocell modem with multiuser interference cancellation technology is presented for the first time. The design and implementation are compliant with the 3GPP/UMTS standard for Wideband Code-Division Multiple Access (WCDMA) baseband air-interface and exceeds 3GPP minimum requirements by 2dB in Additive White Gaussian Noise (AWGN) environment. The modem is designed with conventional and advanced interference cancellation to support up to eight users simultaneously with a mix of voice and data services. The conventional modem can achieve maximum data rate of 2Mbps in the downlink and 384kbps in the uplink. The implementation fully realizes the physical layer transport channel encoder, spreading, and modulation in the downlink, and random access, synchronization and acquisition, channel estimation, despreading, demodulation, and transport channel decoding in the uplink. The design is completely scalable such that the interference cancellation technology is realized on top of the conventional design of the modem to improve the reception sensitivity.

I. Introduction

Femtocells are wireless access points (or micro base stations) specifically designed to achieve connectivity to cellular devices from standards like 3GPP. The advantages of femto-cells include better coverage, higher capacity, lowering costs to wireless operators and minimizing the churn of residential users. Femtocells are enabled by broadband connectivity via xDSL or cable that is becoming pervasive [1], [2].