Abstract: It is provided a method for determining when a portable key device is located on a front side or on a back side in relation to a barrier secured by an electronic lock. The method is performed in a location determiner and comprises the steps of: obtaining a channel impulse response, CIR, based on an impulse signal transmitted from the portable key device, the CIR being based on a plurality of samples of the impulse signal as received by an antenna being fixedly mounted in relation to the electronic lock; and determining, based on the CIR, whether the portable key device is located on the front side or on the back side.

Abstract: It is provided a method for determining whether a portable key device is located inside or outside a metal door. The method is performed by a credential communication device and comprises the steps of: obtaining a first time-of-flight, ToF, measurement between a first antenna and the portable key device, wherein the first antenna is located on the outside of the metal door; obtaining a second ToF measurement between a second antenna and the portable key device, wherein the second antenna is located on the inside of the metal door; and determining the portable key device to be located on the outside of the metal door when the first ToF measurement is less than the second ToF measurement by an amount which is greater than a threshold value.

Abstract: It is provided a method for determining whether a portable key device is located inside or outside a metal door. The method is performed by a credential communication device and comprises the steps of: obtaining a first time-of-flight, ToF, measurement between a first antenna and the portable key device, wherein the first antenna is located on the outside of the metal door; obtaining a second ToF measurement between a second antenna and the portable key device, wherein the second antenna is located on the inside of the metal door; and determining the portable key device to be located on the outside of the metal door when the first ToF measurement is less than the second ToF measurement by an amount which is greater than a threshold value.

Abstract: It is provided a method for determining when a portable key device is located on a front side or on a back side in relation to a barrier secured by an electronic lock. The method is performed in a location determiner and comprises the steps of: obtaining a channel impulse response, CIR, based on an impulse signal transmitted from the portable key device, the CIR being based on a plurality of samples of the impulse signal as received by an antenna being fixedly mounted in relation to the electronic lock; and determining, based on the CIR, whether the portable key device is located on the front side or on the back side.

Abstract: It is provided a location determiner comprising: a first antenna; a radio signal modification device, wherein the radio signal modification device is configured to improve an ability to determine whether the portable key device is located on a back side or on a front side of the location determiner, based on obtaining a channel impulse response, CIR, of an impulse signal transmitted from the portable key device, wherein the location determiner is installable such that the back side is in a space being restricted by selectively unlockable a physical barrier and the front side is opposite the back side.