Nokia Corporation

Nokia Mobile Phones Limited

Nokia Siemens Networks Oy

Intellectual Ventures I LLC

Hans-Otto Scheck

Julius Koskela

Jaroslaw Lachowski

Petteri Alinikula

Timo Ahonpää

Kari-Pekka Estola

Jouko Lokio

Pekka Kukkonen

Timo Poranen

Tapio Vuopala

Adrian Bohdanowicz

Jyrki Alminoja

A digital imbalance correction device and method are provided including an input unit to receive first input signals. A time-to-frequency-domain-transformer performs a transformation of the first input signals from time-domain into frequency-domain. A subtractor receives second input signals and outputs a gain difference as a function of frequency at its output. A cross-correlator receives third input signals based on the input signals, and outputs a cross-correlation of the third input signals. A gain corrector receives a fourth input signal based the associated first input signal. A gain of the fourth input signal is corrected based on the power difference spectrum. A phase corrector receives a fifth input signal based the associated first input signal. A phase of the fifth input signal is corrected based on the cross-correlation output, such that the phase of the fifth input signal is in quadrature relation to the other one of the first input signals.

Digital imbalance correction method and device in a receiver for multi-carrier applications

A direct conversion receiver includes a receiver for receiving a signal including multiple components at different receiving frequencies belonging to a frequency band. A mixer mixes the signal components into a base band signal comprising I- and Q branches. A converter converts the analog base band signal into a digital signal. The receiver includes a measuring unit for measuring power levels of the signal components in pairs, where one component in the pair belongs to an upper sideband of the frequency band and one component in the pair belongs to a lower sideband of the frequency band. An estimator estimates, when either the upper sideband component or the lower sideband component dominates in power over the component in the pair, a frequency-independent phase imbalance, a frequency-dependent phase imbalance and a gain imbalance, and a compensator compensates the estimated imbalances to at least one of the I- and Q-branch signals.

Direct conversion receiver and receiving method

A method for identifying a remote radio unit in a communication system comprises a plurality of remote radio units communicating with a central unit and pattern providing means for providing information about dedicated gain change patterns of the remote radio units. The method comprises receiving a signal from a station by a remote radio unit of the plurality of remote radio units. The method also includes changing the gain of at least one remote radio unit according to a dedicated gain change pattern of the at least one remote radio unit. The method also includes detecting a gain change pattern for the received signal and identifying the remote radio unit by comparing the detected gain change pattern with information about dedicated gain change patterns of the remote radio units provided by the pattern providing means. An example may be locating a station, such as a user equipment, in a distributed radio system.

Identifying remote radio units in a communication system

A radio transmitter, comprising: a feedback loop () which feedback loop comprises a variable attenuator and a signal analyser, means () for transmitting a signal on a predetermined radio channel, means () for changing attenuation level and for attenuating the feedback signal, means () for defining power levels on the radio channel and on the adjacent channels, means () for analysing the power levels to generate first and second results of analysis and for comparing the first and second results of analysis, means () for delaying a transmitted signal to derive a reference signal, means () for comparing the feedback signal and the reference signal to generate an error vector and means () for generating a test alarm.

Radio transmitter testing method, radio transmitter and base station

In a method for compensating D.C. offset in a direct conversion receiver by a signal (IF.sub.-- I, IF.sub.-- Q) received and demodulated in one of the channels of the reception frequency band of a radio communication system, a correction signal (Q.sub.control) is produced from the signals in the channels of the reception frequency band. The correction signal (Q.sub.control) is combined with the demodulated signal. The apparatus for implementing the method comprises means (12, 17, 18, 19) for producing the correction signal, and means (15, 16) for combining the correction signal with the received and demodulated signal.

Elimination of D.C. offset and spurious AM suppression in a direct

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Espoo, Finland

Hans-Otto Scheck