User equipment and method for radio link monitoring

摘要

Techniques are provided for a radio link quality monitoring method and apparatus wherein a given user equipment device receives a plurality of Orthogonal Frequency Division Multiplex symbols that comprise a plurality of resource elements distributed in time and frequency, and which include reference symbols. The objective of the radio link quality monitoring is to predict the user equipment detection probability of control messages transmitted by the base station. The radio link quality estimation process calculates two average signal to noise ratio values over the complete frequency bandwidth for two assumed control channel formats corresponding to in-sync and out-of-sync conditions. The results of the calculations are then used to deduce the average error probabilities that are compared with predefined thresholds to provide the in-sync/out-of-sync indications.

主权项

1. A user equipment, adapted to an Orthogonal Frequency Division Multiplex (OFDM) wireless communication system comprising a base station, the user equipment comprising:
a receiver that receives from at least one antenna a plurality of signals over a set of OFDM symbols transmitted by the base station through a propagation channel, the OFDM symbols comprising a plurality of resource elements distributed in time and frequency, the resource elements comprising a plurality of control messages; a channel estimation module that generates a channel power value and a channel noise power value from the resource elements that are distributed essentially across an entire frequency bandwidth; a demodulator retrieving at least one of the control messages; and a radio link monitoring module, comprising: a signal to noise ratio (SNR) calculation unit that calculates a SNR at the output of the demodulator according to the channel and noise power values, wherein the SNR allows assessing of the quality of the control message which is from the base station, wherein the radio link monitoring module further generates an unbiased channel power by removing a channel estimation error bias from the channel power, wherein an unbiased normalized channel power is obtained by scaling the unbiased channel power value by the noise power value, wherein the radio link monitoring module calculates the channel estimation error bias by scaling the channel noise power value with a factor dependent on a noise rejection in the channel estimation of the resource elements associated with the channel power value and channel noise power value, wherein the channel power and the channel noise power values are calculated separately for the antenna and the channel power and the channel noise power values are combined to generate a SNR value at the output of the demodulator, and wherein the unbiased normalized channel power is represented as:γ=(∑r=1Nrx⁢(Phrσv,r2-1Gc))+ where Phr represents the channel power value for each receiver antenna, σv,r2 represents the noise power value for each receiver antenna, Nrx is the number of receiver antennas, and Gc the noise rejection in the channel estimation of the resource elements associated with the channel power and channel noise power.