LOS training dataset imbalance detection
There is provided a method for a UE of a wireless communication system, the method comprising: detecting an imbalance in a line-of-sight, LOS, training dataset for training a LOS detector; determining a minority class of the LOS training dataset associated with the detected imbalance; transmitting, to a network element of the wireless communication system, a request message indicating the determined minority class and requesting measurement activation to perform one or more measurements, by the UE, to obtain one or more additional signal samples for the minority class; and receiving, from the network element, an activation message causing the UE to perform the one or more measurements during a configured observation window.
1 . An apparatus comprising:
at least one processor; and
at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:
detect an imbalance in a line-of-sight, LOS, training dataset for training a LOS detector;
determine a minority class of the LOS training dataset associated with the detected imbalance;
transmit, to a network element of a wireless communication system, a request message indicating the determined minority class and requesting measurement activation to perform one or more measurements to obtain one or more additional signal samples for the minority class; and
receive, from the network element, an activation message causing the apparatus to perform the one or more measurements during a configured observation window,
wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to:
obtain the one or more additional signal samples for the minority class; and after obtaining the one or more additional signal samples, retraining the LOS detector with the LOS training set,
wherein the activation message comprises observation window configuration information,
wherein the observation window configuration information indicates a duration of the observation window and a start time of the observation window relative to an index of a subframe carrying a predetermined message or relative to a system frame number,
wherein the predetermined message is the request message and the subframe is an uplink subframe, or the predetermined message is the activation message and the subframe is a downlink subframe.
2 . The apparatus of claim 1 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to:
detect class imbalance if the following conditions are fulfilled:
the size of any class in the training dataset is less than a percentage of the size of a majority class,
the size of any class is less than a percentage of the size of the majority class, after untrustworthy signal samples have been discarded or removed,
untrustworthy measurements comprise signal samples having SNR exceeding a threshold, signal samples having RL exceeding a RL threshold, and signal samples having Doppler shift exceeding a threshold, and
the size of any class is less than a given percentage of the size of the majority class and Δt has passed since the latest signal sample has been collected.
3 . The apparatus of claim 1 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to:
after a class imbalance is detected, send to the network a reconfiguration request for obtaining new channel signal samples belonging to the minority class;
report, to the network element, the severity of the class imbalance comprising an imbalance ratio, an indicator of the imbalance and of the relative sizes of the different class signal samples;
determine the severity of the imbalance by determining how many additional signal samples for the minority class is required to at least reduce the imbalance to an acceptable level, the acceptable level being network configured or preconfigured, or determined by the LOS detector).
4 . The apparatus of claim 1 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to:
receiving, from the network element, a configuration message comprising observation window configuration information.
5 . The apparatus of claim 4 , wherein the signal samples may directly indicate and comprise parameters and indicators that include at least signal power, received signal strength indicator (RSSI), signal-to-noise-plus-interference-ratio (SINR), signal-to-noise-ratio (SNR), Doppler shift, channel impulse response and power delay power.
6 . The apparatus of claim 5 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor cause the apparatus to:
collect the signal samples by performing measurements in the configured observation window;
tag the signal samples with a corresponding class label;
timestamps the signal samples; and
buffer the signal samples internally.
7 . The apparatus of claim 1 , wherein the request message further comprises a severity indicator being indicative of a severity of the imbalance.
8 . The apparatus of claim 1 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to:
receive, from the network element, an imbalance threshold value; determine whether the imbalance satisfies the imbalance threshold value; and
based on determining that the imbalance satisfies the imbalance threshold, transmit the request message to the network element, otherwise prevent transmitting the request message.
9 . The apparatus of claim 1 , wherein the activation message indicates acknowledgement, ACK, or non-acknowledgement, NACK, wherein an indication of ACK causes the apparatus to perform the one or more measurements during the configured observation window, and wherein an indication of NACK causes the apparatus to prevent performing the one or more measurements.
10 . The apparatus of claim 1 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to:
receive, from the network element, a reference symbol configuration to be used for retraining the LOS detector; and
utilize the reference symbol configuration in retraining the LOS detector by initiating reception of training signals according to the reference symbol configuration.
11 . An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:
receive a request message from a user equipment, UE, of a wireless communication system, the request message indicating a minority class associated with an imbalance in a line-of-sight, LOS, training dataset for training a LOS detector and requesting measurement activation to perform one or more measurements, by the UE, to obtain one or more additional signal samples for the minority class; and
transmit, to the UE, an activation message causing the UE to perform the one or more measurements during a configured observation window,
wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to:
obtain a location estimation about at least one future location of the UE;
estimate radio condition at said at least one future location; determine, based on the estimated radio condition at said at least one future location, a time for transmitting the activation message;
and transmit the activation message at said time.
12 . A method for a user equipment, UE, of a wireless communication system, the method comprising:
detecting an imbalance in a line-of-sight, LOS, training dataset for training a LOS detector;
determining a minority class of the LOS training dataset associated with the detected imbalance; transmitting, to a network element of the wireless communication system, a request message indicating the determined minority class and requesting measurement activation to perform one or more measurements, by the UE, to obtain one or more additional signal samples for the minority class; and
receiving, from the network element, an activation message causing the UE to perform the one or more measurements during a configured observation window,
wherein the method further comprises:
obtaining the one or more additional signal samples for the minority class; and after obtaining the one or more additional signal samples, retraining the LOS detector with the LOS training set,
wherein the activation message comprises observation window configuration information,
wherein the observation window configuration information indicates a duration of the observation window and a start time of the observation window relative to an index of a subframe carrying a predetermined message or relative to a system frame number,
wherein the predetermined message is the request message and the subframe is an uplink subframe, or the predetermined message is the activation message and the subframe is a downlink subframe.