US 8,477,592 B2 · Interference and noise estimation in an OFDM system

Abstract

Noise and interference can be independently measured in a multiple user Orthogonal Frequency Division Multiplexing (OFDM) system. Co-channel interference is measured in a frequency hopping, multiple user, OFDM system by tracking the sub-carriers assigned to all users in a particular service area or cell. The composite noise plus interference can be determined by measuring the amount of received power in a sub-carrier whenever it is not assigned to any user in the cell. A value is stored for each sub-carrier in the system and the value of noise plus interference can be a weighted average of the present value with previously stored values. The noise component can be independently determined in a synchronous system. In the synchronous system, all users in a system may periodically be prohibited from broadcasting over a sub-carrier and the received power in the sub-carrier measured during the period having no broadcasts.

Claims26

Dependent claims

A method of estimating noise in an Orthogonal Frequency Division Multiplexing (OFDM) system, the method comprising:

receiving OFDM symbols in a wireless cellular communication system, the OFDM symbols corresponding to a symbol period;
determining an idle sub-carrier frequency band during the symbol period, wherein the idle sub-carrier frequency band includes only noise and interference;
determining a power, during the symbol period, in a frequency band corresponding to the idle sub-carrier frequency band;
storing a value of the power of the idle sub-carrier frequency band in a memory;
and
computing a weighted average of the power of the idle sub-carrier frequency band with previously stored values to generate a noise estimate, wherein weights for the weighted average are based on ages of the previously stored values.

3 more elements

Dependencies are inferred from the claim text.

Interference and noise estimation in an OFDM system

Life of this patent

Interference and noise estimation in an OFDM system

Life of this patent

Abstract

Claims26