Measured GPS performance under LTE-M in-device interference

Abstract

In this paper we present the measurement results for time-to-fix, position accuracy, and carrier-to-noise ratio of commercial Global Positioning System (GPS) receivers under the in-device interference from an LTE-M transmitter. The laboratory measurement set-up is built using software-defined radio (SDR) platforms to conductively feed emulated GPS L1 signals and LTE-M interference signals to the antenna input of the GPS receivers. The LTE-M interference from second harmonics is accurately modelled taking into account the transmitter activity patterns in different coverage enhancement modes. According to measurements, there are large variations in interference tolerance between different GPS receivers. REC01 was able to tolerate high level of interference during tracking and also in acquisition as long as the interference pulse duration is not too long (tens of milliseconds). REC02 performed clearly worse and tolerated only low levels of LTE-M interference during both acquisition and tracking. The same measurement set-up can be used with any GPS receiver for designing proper isolation and filtering levels for co-existing LTE-M transmitters.

Study and Analysis of Interference Signals of the LTE System of the GNSS Receiver

“…The research described in [ 34 , 35 ] indicate that a transmitter transmitting an interfering signal with a power of 244 mW, in a bandwidth of 2 MHz, is sufficient to prevent the reception of GPS signals within a radius of more than 6 km when the receiver is tuned to signals from satellites and within a radius of more than 8 km when the receiver is not yet synchronized with them.…”

“…The research described in [ 34 , 35 ] has also shown that strong interference outside the GNSS systems band may also have a negative impact on the quality of reception of navigation signals. The algorithms that are used to calculate the ratio of the carrier wave power to the spectral power density of the noise make it possible to make a measurable assessment of the quality of the received signals.…”

“…The analysis of the available literature shows that currently conducted studies of this type are generally carried out under fairly favorable and established conditions, which are often manifested by the unlimited visibility of the celestial sphere. The main analysis parameter is the BER (Bit Error Rate) parameter evaluating the ratio of the correct signal to the interference signal [ 34 , 35 ].…”

Acquisition performance of B1I abounding with 5G signals

“…The long term evaluation (LTE) signal proposed by Light Square was rejected by the Federal Communications Commission (FCC) due to the severe performance degradation of various GPS receivers in real tests [2]. The influence of the third harmonics of DVB-T signals on GPS L1/Galileo E1 was also tested with the carrier to noise ratio (CNR) as an evaluation indicator [3]. The impact of LTE-machine to machine (LTE-M) second harmonics on GPS receivers was also evaluated in terms of its positioning error and CNR reduction.…”