6.5.6 WLAN-based Positioning
37.3553GPPLTE Positioning Protocol (LPP)Release 17TS
This clause defines support for positioning using measurements related to WLAN access points.
6.5.6.1 WLAN Location Information
– WLAN-ProvideLocationInformation
The IE WLAN-ProvideLocationInformation is used by the target device to provide measurements for one or more WLANs to the location server. It may also be used to provide WLAN positioning specific error reason.
— ASN1START
WLAN-ProvideLocationInformation-r13 ::= SEQUENCE {
wlan-MeasurementInformation-r13 WLAN-MeasurementInformation-r13 OPTIONAL,
wlan-Error-r13 WLAN-Error-r13 OPTIONAL,
…
}
— ASN1STOP
6.5.6.2 WLAN Location Information Elements
– WLAN-MeasurementInformation
— ASN1START
WLAN-MeasurementInformation-r13 ::= SEQUENCE {
measurementReferenceTime-r13 UTCTime OPTIONAL,
wlan-MeasurementList-r13 WLAN-MeasurementList-r13 OPTIONAL,
…
}
WLAN-MeasurementList-r13 ::= SEQUENCE (SIZE(1..maxWLAN-AP-r13)) OF WLAN-MeasurementElement-r13
WLAN-MeasurementElement-r13 ::= SEQUENCE {
wlan-AP-Identifier-r13 WLAN-AP-Identifier-r13,
rssi-r13 INTEGER (-127..128) OPTIONAL,
rtt-r13 WLAN-RTT-r13 OPTIONAL,
apChannelFrequency-r13 INTEGER (0..256) OPTIONAL,
servingFlag-r13 BOOLEAN OPTIONAL,
…
}
WLAN-AP-Identifier-r13 ::= SEQUENCE {
bssid-r13 OCTET STRING (SIZE (6)),
ssid-r13 OCTET STRING (SIZE (1..32)) OPTIONAL,
…
}
WLAN-RTT-r13 ::= SEQUENCE {
rttValue-r13 INTEGER (0..16777215),
rttUnits-r13 ENUMERATED { microseconds,
hundredsofnanoseconds,
tensofnanoseconds,
nanoseconds,
tenthsofnanoseconds,
… },
rttAccuracy-r13 INTEGER (0..255) OPTIONAL,
…
}
— ASN1STOP
WLAN-MeasurementInformation field descriptions |
---|
measurementReferenceTime This field provides the UTC time when the WLAN measurements are performed and should take the form of YYMMDDhhmmssZ. |
wlan-MeasurementList This field provides the WLAN measurements for up to 64 WLAN APs. |
wlan-AP-Identifier This field provides the BSSID and optionally the SSID of the wireless network served by the WLAN AP [26]. |
rssi This field provides the AP signal strength (RSSI) of a beacon frame, probe response frame or measurement pilot frame measured at the target in dBm as defined in Table 6-7 of [26]. |
rtt This field provides the measured round trip time between the target device and WLAN AP and optionally the accuracy expressed as the standard deviation of the delay. Units for each of these are 1000ns, 100ns, 10ns, 1ns, and 0.1ns. |
apChannelFrequency This field provides the AP channel number identification of the reported WLAN AP. |
servingFlag This parameter indicates whether a set of WLAN AP measurements were obtained for a serving WLAN AP (TRUE) or a non-serving WLAN AP (FALSE). A target device with multiple radio support may indicate more than one type of serving access for the same time instant. |
rttValue This field specifies the Round Trip Time (RTT) measurement between the target device and WLAN AP in units given by the field rttUnits. |
rttUnits This field specifies the Units for the fields rttValue and rttAccuracy. The available Units are 1000ns, 100ns, 10ns, 1ns, and 0.1ns. |
rttAccuracy This field provides the estimated accuracy of the provided rttValue expressed as the standard deviation in units given by the field rttUnits. |
6.5.6.3 WLAN Location Information Request
– WLAN-RequestLocationInformation
The IE WLAN-RequestLocationInformation is used by the location server to request WLAN measurements from a target device.
— ASN1START
WLAN-RequestLocationInformation-r13 ::= SEQUENCE {
requestedMeasurements-r13 BIT STRING {
rssi (0),
rtt (1)} (SIZE(1..8)),
…,
[[ assistanceAvailability-r14 BOOLEAN OPTIONAL — Need ON
]]
}
— ASN1STOP
WLAN-RequestLocationInformation field descriptions |
---|
requestedMeasurements This field specifies the WLAN measurements requested. This is represented by a bit string, with a one‑value at the bit position means the particular measurement is requested; a zero‑value means not requested. The following measurement requests can be included. rssi: AP signal strength at the target rtt: Round Trip Time between target and AP |
assistanceAvailability This field indicates whether the target device may request additional WLAN assistance data from the server. TRUE means allowed and FALSE means not allowed. |
6.5.6.4 WLAN Capability Information
– WLAN-ProvideCapabilities
The IE WLAN-ProvideCapabilites is used by the target device to provide its capabilities for WLAN positioning to the location server.
— ASN1START
WLAN-ProvideCapabilities-r13 ::= SEQUENCE {
wlan-Modes-r13 BIT STRING { standalone (0),
ue-assisted (1),
ue-based (2)} (SIZE (1..8)),
wlan-MeasSupported-r13 BIT STRING {
rssi-r13 (0),
rtt-r13 (1)} (SIZE(1..8)),
… ,
[[ wlan-AP-AD-Supported-r14
BIT STRING { ap-identifier (0),
ap-location (1)} (SIZE (1..8))
OPTIONAL,
periodicalReportingSupported-r14 PositioningModes OPTIONAL,
idleStateForMeasurements-r14
ENUMERATED { required } OPTIONAL
]],
[[ scheduledLocationRequestSupported-r17 ScheduledLocationTimeSupportPerMode-r17 OPTIONAL
]]
}
— ASN1STOP
WLAN-ProvideCapabilities field descriptions |
---|
wlan-Modes This field specifies the WLAN mode(s) supported by the target device. This is represented by a bit string, with a one value at the bit position means the WLAN mode is supported; a zero value means not supported. |
wlan-MeasSupported This field specifies the measurements supported by the target device when accessing a WLAN. This is represented by a bit string, with a one‑value at the bit position means the particular measurement is supported; a zero‑value means not supported. A zero-value in all bit positions in the bit string means only the basic WLAN positioning method is supported by the target device which is reporting of the WLAN identity. The following bits are assigned for the indicated measurements. rssi: AP signal strength at the target rtt: Round Trip Time between target and AP |
wlan-AP-AD-Supported ap-identifier: WLAN AP identity information ap-location: WLAN AP location information |
periodicalReportingSupported This field, if present, specifies the positioning modes for which the target device supports periodicalReporting. This is represented by a bit string, with a one value at the bit position means periodicalReporting for the positioning mode is supported; a zero value means not supported. If this field is absent, the location server may assume that the target device does not support periodicalReporting in CommonIEsRequestLocationInformation. |
idleStateForMeasurements This field, if present, indicates that the target device requires idle state to perform WLAN measurements. |
scheduledLocationRequestSupported This field, if present, specifies the positioning modes for which the target device supports scheduled location requests – i.e., supports the IE ScheduledLocationTime in IE CommonIEsRequestLocationInformation – and the time base(s) supported for the scheduled location time for each positioning mode. If this field is absent, the target device does not support scheduled location requests. |
6.5.6.5 WLAN Capability Information Request
– WLAN-RequestCapabilities
The IE WLAN-RequestCapabilities is used by the location server to request WLAN positioning capabilities information from a target device.
— ASN1START
WLAN-RequestCapabilities-r13 ::= SEQUENCE {
…
}
— ASN1STOP
6.5.6.6 WLAN Error Elements
– WLAN-Error
The IE WLAN-Error is used by the location server or target device to provide error reasons for WLAN positioning to the target device or location server, respectively.
— ASN1START
WLAN-Error-r13 ::= CHOICE {
locationServerErrorCauses-r13 WLAN-LocationServerErrorCauses-r13,
targetDeviceErrorCauses-r13 WLAN-TargetDeviceErrorCauses-r13,
…
}
— ASN1STOP
– WLAN-LocationServerErrorCauses
The IE WLAN-LocationServerErrorCauses is used by the location server to provide error reasons for WLAN positioning to the target device.
— ASN1START
WLAN-LocationServerErrorCauses-r13 ::= SEQUENCE {
cause-r13 ENUMERATED {undefined,
…,
requestedADNotAvailable-v1420,
notAllrequestedADAvailable-v1420
},
…,
[[ apLocationDataUnavailable-r14 NULL OPTIONAL — Need ON
]]
}
— ASN1STOP
WLAN-LocationServerErrorCauses field descriptions |
---|
cause This field provides a WLAN AP specific error cause for the server applicable to provision of assistance data. If the cause value is ‘requestedADNotAvailable‘, none of the requested assistance data could be provided and no further information needs to be included. If the cause value is ‘notAllRequestedADAvailable‘, the server was able to provide some but not all requested WLAN AP assistance data. In this case, the server should include any of the specific error indications as applicable. Note that inclusion of these fields is applicable when some of the associated information can be provided for some WLAN APs but not for all WLAN APs. |
– WLAN-TargetDeviceErrorCauses
The IE WLAN-TargetDeviceErrorCauses is used by the target device to provide error reasons for WLAN positioning to the location server.
— ASN1START
WLAN-TargetDeviceErrorCauses-r13 ::= SEQUENCE {
cause-r13 ENUMERATED {undefined,
requestedMeasurementsNotAvailable,
notAllrequestedMeasurementsPossible,
…
},
wlan-AP-RSSI-MeasurementNotPossible-r13 NULL OPTIONAL,
wlan-AP-RTT-MeasurementNotPossible-r13 NULL OPTIONAL,
…
}
— ASN1STOP
WLAN-TargetDeviceErrorCauses field descriptions |
---|
cause This field provides a WLAN specific error cause. If the cause value is ‘notAllRequestedMeasurementsPossible’, the target device was not able to provide all requested WLAN measurements (but may be able to provide some measurements). In this case, the target device should include any of the wlan‑AP‑RSSI‑MeasurementNotPossible, or wlan‑AP‑RTT‑MeasurementNotPossible fields, as applicable. |
6.5.6.7 WLAN Assistance Data
– WLAN-ProvideAssistanceData
The IE WLAN-ProvideAssistanceData is used by the location server to provide assistance data to enable UE‑based and UE-assisted WLAN positioning. It may also be used to provide WLAN positioning specific error reason.
— ASN1START
WLAN-ProvideAssistanceData-r14 ::= SEQUENCE {
wlan-DataSet-r14 SEQUENCE (SIZE (1..maxWLAN-DataSets-r14)) OF WLAN-DataSet-r14
OPTIONAL, — Need ON
wlan-Error-r14 WLAN-Error-r13 OPTIONAL, — Need ON
…
}
— ASN1STOP
WLAN-ProvideAssistanceData field descriptions |
---|
wlan-DataSet |
wlan-Error |
6.5.6.8 WLAN Assistance Data Elements
– WLAN-DataSet
The IE WLAN-DataSet is used by the location server to provide WLAN AP information for one set of WLAN APs.
— ASN1START
WLAN-DataSet-r14 ::= SEQUENCE {
wlan-AP-List-r14 SEQUENCE (SIZE (1..maxWLAN-AP-r14)) OF WLAN-AP-Data-r14,
supportedChannels-11a-r14 SupportedChannels-11a-r14 OPTIONAL, — Need ON
supportedChannels-11bg-r14 SupportedChannels-11bg-r14 OPTIONAL, — Need ON
…
}
SupportedChannels-11a-r14 ::= SEQUENCE {
ch34-r14 BOOLEAN,
ch36-r14 BOOLEAN,
ch38-r14 BOOLEAN,
ch40-r14 BOOLEAN,
ch42-r14 BOOLEAN,
ch44-r14 BOOLEAN,
ch46-r14 BOOLEAN,
ch48-r14 BOOLEAN,
ch52-r14 BOOLEAN,
ch56-r14 BOOLEAN,
ch60-r14 BOOLEAN,
ch64-r14 BOOLEAN,
ch149-r14 BOOLEAN,
ch153-r14 BOOLEAN,
ch157-r14 BOOLEAN,
ch161-r14 BOOLEAN
}
SupportedChannels-11bg-r14 ::= SEQUENCE {
ch1-r14 BOOLEAN,
ch2-r14 BOOLEAN,
ch3-r14 BOOLEAN,
ch4-r14 BOOLEAN,
ch5-r14 BOOLEAN,
ch6-r14 BOOLEAN,
ch7-r14 BOOLEAN,
ch8-r14 BOOLEAN,
ch9-r14 BOOLEAN,
ch10-r14 BOOLEAN,
ch11-r14 BOOLEAN,
ch12-r14 BOOLEAN,
ch13-r14 BOOLEAN,
ch14-r14 BOOLEAN
}
— ASN1STOP
WLAN-DataSet field descriptions |
---|
wlan-AP-List |
supportedChannels-11a |
supportedChannels-11bg |
– WLAN-AP-Data
The IE WLAN-AP-Data is used by the location server to provide information for one WLAN AP as part of WLAN AP assistance data.
— ASN1START
WLAN-AP-Data-r14 ::= SEQUENCE {
wlan-AP-Identifier-r14 WLAN-AP-Identifier-r13,
wlan-AP-Location-r14 WLAN-AP-Location-r14 OPTIONAL, — Need ON
…
}
WLAN-AP-Location-r14 ::= SEQUENCE {
locationDataLCI-r14 LocationDataLCI-r14,
…
}
LocationDataLCI-r14 ::= SEQUENCE {
latitudeUncertainty-r14 BIT STRING (SIZE (6)),
latitude-r14 BIT STRING (SIZE (34)),
longitudeUncertainty-r14 BIT STRING (SIZE (6)),
longitude-r14 BIT STRING (SIZE (34)),
altitudeUncertainty-r14 BIT STRING (SIZE (6)) OPTIONAL, — Need ON
altitude-r14 BIT STRING (SIZE (30)) OPTIONAL, — Need ON
datum-r14 BIT STRING (SIZE (8)),
…
}
— ASN1STOP
WLAN-AP-Data field descriptions |
---|
wlan-AP-Location – locationDataLCI This field provides the location of the WLAN AP in the form of Location Configuration Information (LCI) defined in [27] and includes the following subfields: latitudeUncertainty: 6-bits quantifying the amount of uncertainty in latitude. A value of 0 is reserved to indicate that the uncertainty is unknown; values greater than 34 are reserved. Its relation with the corresponding value in degrees is expressed with the following formula: latitude: A 34-bits fixed point value consisting of 9-bits of integer and 25-bits of fraction indicating the Latitude (+/- 90 degrees) of the AP. longitudeUncertainty: 6-bits quantifying the amount of uncertainty in longitude. A value of 0 is reserved to indicate that the uncertainty is unknown; values greater than 34 are reserved. Its relation with the corresponding value in degrees is expressed with the following formula: longitude: A 34-bits fixed point value consisting of 9-bits of integer and 25-bits of fraction indicating the Longitude (+/- 180 degrees) of the AP. altitudeUncertainty: 6-bits value quantifying the amount of uncertainty in the altitude value. A value of 0 is reserved to indicate that the uncertainty is unknown; values greater than 30 are reserved. Its relation with the corresponding value in metres is expressed with the following formula: altitude: A 30-bit fixed point value consisting of 22-bits of integer and 8-bits of fraction indicating the altitude of the AP in metres. datum: 8-bits indicating the map datum used for the coordinates. Defined codes are: |
6.5.6.9 WLAN Assistance Data Request
– WLAN-RequestAssistanceData
The IE WLAN-RequestAssistanceData is used by the target device to request WLAN assistance data from a location server.
— ASN1START
WLAN-RequestAssistanceData-r14 ::= SEQUENCE {
requestedAD-r14 BIT STRING { ap-identifier (0),
ap-location (1)} (SIZE (1..8)),
visibleAPs-r14 SEQUENCE (SIZE (1..maxVisibleAPs-r14)) OF WLAN-AP-Identifier-r13 OPTIONAL,
wlan-AP-StoredData-r14 SEQUENCE (SIZE (1..maxKnownAPs-r14)) OF WLAN-AP-Identifier-r13 OPTIONAL,
…
}
— ASN1STOP
WLAN-RequestAssistanceData field descriptions |
---|
requestedAD ap-identifier: WLAN AP identity information |
visibleAPs |
wlan-AP-StoredData |