1/f Baseband Noise Suppression in OFDM Systems

The commonly used direct-conversion Radio Frequency (RF) chips exhibit an additive 1/f baseband noise around the DC. The 1/f noise level increases as the transistors inside the RF chip become ever smaller. This type of noise mainly affects the low frequencies and can be very significant for small frequency allocations around the DC in Orthogonal Frequency-Division Multiple Access (OFDMA) systems. In this article we present the effects of such 1/f baseband noise on small frequency allocations for a Long Term Evolution (LTE) User Equipment (UE). We proceed to estimate the 1/f baseband noise. Suppression of the 1/f baseband noise is achieved by subtracting the estimated 1/f baseband noise from the received signal. We show that considerable processing gain is achieved when the 1/f baseband noise suppression is applied.