A.2 Measure Position Request

3GPP44.031Location Services (LCS)Mobile Station (MS) - Serving Mobile Location Centre (SMLC) Radio Resource LCS Protocol (RRLP)Release 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

A.2.1 General

The Measure Position Request is a RRLP component from the SMLC to the MS. This component is common to E-OTD,GPS and GANSS (Galileo and Additional Navigation Satellite Systems) location methods. As a response to this component, the MS performs E-OTD,GPS or GANSS measurements and possibly calculates its own position, if the MS and/or the network support these options. It contains the following elements.

Table A.1: Measure Position Request component content

Element	Type/Reference	Presence
Positioning Instructions	Positioning Instructions 2.2.1	M
E-OTD Reference BTS for Assistance Data	E-OTD Reference BTS for Assistance Data 2.2.2	O
E-OTD Measurement Assistance Data	E-OTD Measurement Assistance Data 2.2.3	O
E-OTD Measurement Assistance Data for System Information List	E-OTD Measurement Assistance Data for System Information List 2.2.4	O
GPS Assistance Data	GPS Assistance Data 4.2.4	O
Additional GPS Assistance Data	Additional GPS Assistance Data 4.2.4c	O
GPS Time Assistance Measurement Request	GPS Time Assistance Measurement Request 2.2.4a	O
GPS Reference Time Uncertainty	GPS Reference Time Uncertainty 2.2.4b	O
Velocity Request	Velocity Request 2.2.4c	O
Extended Reference	Extended Reference 2.2.5	O
GANSS Positioning Method Element	GANSS Positioning Method Element 2.2.1a	O
GANSS Carrier-Phase Measurement Request	GANSS Carrier-Phase Measurement Request 2.2.4d	O
GANSS TOD – GSM Time Association Request	GANSS TOD – GSM Time Association Request 2.2.4e	O
GANSS Multi-frequency Measurement Request	GANSS Multi-frequency Measurement Request 2.2.4g	O
GANSS Assistance Data	GANSS Assistance Data 4.2.6	O
Required Response Time	Required Response Time 2.2.4f	O

A.2.2 Elements

A.2.2.1 Positioning Instructions Element

The purpose of Positioning Instructions element is to express the allowed/required location method(s), and to provide information required QoS. This element is mandatory in the Measure Position Request message, and contains the following fields:

Method Type

This field indicates whether MS based or assisted version is allowed/requested. If the Positioning Methods field includes more than one method, the Method Type applies to all of them. This field is mandatory, and has the following values:

‘0’: MS assisted;

‘1’: MS based;

‘2’: MS based is preferred, but MS assisted is allowed;

‘3’: MS assisted is preferred, but MS based is allowed.

In GPS positioning methods, ‘MS based’ may indicate either MS Based Assisted GPS method or Conventional GPS method. If ‘MS based is indicated with no GPS assistance data then the MS may interpret this as either Conventional GPS or MS based A-GPS without assistance data. The same interpretation applies also to the GANSS positioning method.

Positioning Methods

This field indicates which location method or methods should be used. This field is mandatory.

‘0’: E-OTD;

‘1’: GPS;

‘2’: E-OTD or GPS (i.e. both can be reported).

NOTE: If the selected positioning method is ‘GPS’ or ‘E-OTD or GPS’, the field GANSS Positioning Method, if present in a Measure Position Request component, indicates request of GANSS method and indicates the allowed satellite systems.

Response Time

This field indicates the desired response time. However, when performing measurements, the desired response time may be exceeded. This field is mandatory.

The response time is 2^N seconds, where N is the value in this field. Thus the desired maximum response time can be 1, 2, 4, 8, 16, 32, 64, or 128 seconds.

Range: 0-7

Accuracy

This field indicates the required accuracy of the location estimate. This is field is mandatory when Method Type is ‘1’, ‘2’, or ‘3’ and optional when Method Type is ‘0’.

This field is 7 bit Uncertainty Code as defined in 3GPP TS 23.032.

Multiple Sets

This field indicates whether MS is requested to send multiple E-OTD/GPS/GANSS Measurement Information Sets. The maximum number of measurement sets is three. This is field is mandatory. MS is expected to include the current measurement set. Additionally MS may include historical measurement sets, or measure new additional sets if the response time allows that.

‘0’: multiple IEs can be send;

‘1’: sending of multiple sets is not allowed.

Environment Characterization

Environment Characterization field provides the MS with information about expected multipath and NLOS in the current area. This field is optional.

‘0’: possibly heavy multipath and NLOS conditions (e.g. bad urban or urban).

‘1’: no or light multipath and usually LOS conditions (e.g. suburban or rural).

‘2’: not defined or mixed environment.

‘3’: reserved for future use.

A.2.2.1a GANSS Positioning Method Element

This bit map indicates the satellite systems allowed by the SMLC corresponding to allowance of ‘GPS’ in the Positioning Methods field. Each bit is of type Boolean, where TRUE (‘1’) means the particular satellite system is allowed. For example EOTD + Galileo method can be indicated by setting ‘E-OTD or GPS’ in Positioning Methods and setting only the ‘bit 1’ to TRUE value in the GANSS Positioning Method element. The MS shall not request assistance data or report measurements for the systems that are not indicated in the bit map.

NOTE: Bit 0 of this bit map shall not be the only one set to TRUE (‘1’).

‘bit 0’: GPS;

‘bit 1’: Galileo;

‘bit 2’: SBAS (WAAS, EGNOS, MSAS, GAGAN);

‘bit 3’: Modernized GPS (L1C, L2C, L5);

‘bit 4’: QZSS;

‘bit 5’: GLONASS;

‘bit 6’: BDS;

‘bit 7-15’: Reserved for future GNSSes.

A.2.2.2 E-OTD Reference BTS for Assistance Data Element

The RTD and 51 multiframe offset values in the E-OTD Measurement Assistance Data element and the E-OTD Measurement Assistance Data for System Information List element are calculated relative to the BTS indicated in this element. Also the E-OTD Measurement Assistance data for System Information List element, if present, refers to the System Information Neighbor List of this reference BTS.

Inclusion of this parameter is mandatory for E-OTD since it is not possible to reliably default to the current serving BTS for the target MS, as there is a small chance that the SMLC does not know this. If the E-OTD Measurement Assistance data for System Information List element is present, the current serving cell must be the same as reference BTS identified in this element.

BCCH Carrier

This field indicates the absolute RF channel number of BCCH of the reference BTS. This field is mandatory.

Range: 0 – 1023

BSIC

This field indicates the BSIC (Base Station Identity Code) of the reference BTS. This field is mandatory.

Range: 0 – 63

Time Slot Scheme

The Time Slot Scheme field indicates the type of transmission scheme the reference BTS is using. If the MS measures BTSs signals from time slots other than 0 or 4, and it is informed about the burst length schemes used by BTSs, then it can compensate for the possible error. (This is necessary if the MS averages bursts from different time slots, and the BTS uses varying lengths of bursts.) This field is mandatory.

‘0’ = all time slots are 156,25 bits long.

‘1’ = time slots 0 and 4 are 157 bits long and other time slots are 156 bits long.

BTS Position

This field contains the BTS position in the format defined in 3GPP TS 23.032. This field is optional, but should be present for MS based E-OTD positioning. The allowed shapes are:

– ellipsoid point;

– ellipsoid point with altitude and uncertainty ellipsoid.

A.2.2.3 E-OTD Measurement Assistance Data Element

This element identifies BTSs that are used for E-OTD measurements. This element helps the MS to make measurements from neighbor BTS (even below decoding level). This element is optional in the Measure Position Request component. The presence of this element means that the MS should try to measure the E-OTD values between the reference BTS and the BTSs identified in this element.

This element is used to deliver E-OTD measurement assistance data for those BTSs, that are not included in the System Information Neighbor List of the reference BTS, if necessary.

The RTD and 51 multiframe offset values are calculated relative to the BTS indicated in the E-OTD Reference BTS for Assistance Data element. This element contains the following fields.

Number of BTSs

This field indicates how many BTSs are included in this IE. This field is mandatory. The maximum number of BTSs in this message for whom the assistance data can be given is 16 (reference BTS and 15 neigbour BTSs). Thus the sum of Number of BTSs field in this IE and total amount of E-OTD Neighbor present bits with value ‘1’ in E-OTD Measurement Assistance Data for System Information List IE can be at a maximum 15.

Range: 1 to 15.

The following fields are repeated for the number of BTSs included in the Number of BTSs field.

BCCH Carrier

This field indicates the absolute RF channel number of BCCH of the particular BTS. This field is mandatory.

Range: 0 – 1023

BSIC

This field indicates the BSIC (Base Station Identity Code) of the particular BTS. This field is mandatory.

Range: 0 – 63

Multiframe Offset

This field indicates the frame difference between the start of the 51 multiframes frames being transmitted from this BTS and the reference BTS. The multiframe offset is defined as T_BTS– T_Ref, where T_BTS is the time of the start of the 51 multiframe in the BTS in question, and T_Ref is the time of the start of the 51 multiframe in the reference BTS. This field is mandatory. Multiframe Offset may be used to calculate the Expected Multiframe Offset (the Multiframe Offset value that MS is expected to measure between this BTS and reference BTS in its current estimated location).

Expected Multiframe Offset = (Multiframe Offset + Adjustment) modulo 51

Adjustment = 1 if Rough RTD – Expected OTD >= 850

Adjustment = -1 if Rough RTD – Expected OTD =< -850

Adjustment = 0 if -400 =< Rough RTD – Expected OTD =< 400

If the Rough RTD – Expected OTD is not within any of the ranges above, an error has occurred and the Expected OTD should be ignored and no Expected Multiframe Offset can be calculated.

Range: 0 – 51

Usable range of Multiframe Offset value is 0 – 50. The Multiframe Offset value 51 shall not be encoded by the transmitting entity and shall be treated by the receiving entity as 0.

Time Slot Scheme

The Time Slot Scheme field indicates the type of transmission scheme the particular BTS is using. If the MS measures BTSs signals from time slots other than 0 or 4, and it is informed about the burst length schemes used by BTSs, then it can compensate for the possible error. (This is necessary if the MS averages bursts from different time slots, and the BTS uses varying lengths of bursts.) This field is mandatory.

‘0’ = all time slots are 156,25 bits long.

‘1’ = time slots 0 and 4 are 157 bits long and other time slots are 156 bits long.

Rough RTD

This field indicates the rough RTD value between this BTS and reference BTS. The used resolution is 1 bits. This RTD value is the RTD value of TS0s (i.e. the difference in starting of TS0), not only the RTD between starts of bursts. The RTD is defined as T_BTS– T_Ref, where T_BTS is the time of the start of TS0 in the BTS in question, and T_Ref is the time of the start of the TS0 in the reference BTS. This field is mandatory.

Range: 0 – 1250

Usable range of Rough RTD value is 0 – 1249. The Rough RTD value 1250 shall not be encoded by the transmitting entity and shall be treated by the receiving entity as 0.

Accurate RTD values are needed for MS based E-OTD, i.e. when the MS calculates its own position.

Expected OTD

This field indicates the OTD value that MS is expected to measure between this BTS and reference BTS in its current estimated location. SMLC can estimate MS’s location roughly e.g. based on serving BTS coordinates, TA, and possibly some other information. The used resolution is 1 bits. This OTD value is the OTD value of TS0s (i.e. the difference in starting of TS0), not only the OTD between starts of bursts. The OTD is defined as T_BTS– T_Ref, where T_BTS is the time of the start of TS0 in the BTS in question, and T_Ref is the time of the start of the TS0 in the reference BTS. This is element is Release 98 extension and it is an optional element included in Release98-Ext IE. SMLC shall send this element to MS supporting MS Assisted or MS Based E-OTD.

Range: 0 – 1250

Usable range of Expected OTD value is 0 – 1249. The Expected OTD value 1250 shall not be encoded by the transmitting entity and shall be treated by the receiving entity as 0.

Uncertainty Of Expected OTD

This field indicates the uncertainty in Expected OTD value. The uncertainty is related to SMLC’s estimation of MS’s location. The uncertainty defines following search window for MS, that it can use to speed up the OTD measurements:

Expected OTD – Uncertainty < measured OTD < Expected OTD + Uncertainty.

This is element is Release 98 extension and it is an optional element included in Release98-Ext IE. SMLC shall send this element to MS supporting MS Assisted or MS Based E-OTD.

Range is 0 – 7 with following encoding:

‘0’ 0 < uncertainty <= 2 bit;

‘1’ 2 < uncertainty <= 4 bit;

‘2’ 4 < uncertainty <= 8 bit;

‘3’ 8 < uncertainty <= 12 bit;

‘4’ 12 < uncertainty <= 16 bit;

‘5’ 16 < uncertainty <= 22 bit;

‘6’ 22 < uncertainty <= 30 bit;

‘7’ uncertainty > 30 bit.

NOTE: If uncertainty in MS’s location is x bits, uncertainty in Expected OTD is 2*x (in the worst case). When the uncertainty is given with value ‘7’ no upper bound exist for the uncertainty.

The following fields tell the coordinates of neighbor BTSs that are used for E-OTD measurements, and also fine RTD values. This information allows the MS to calculate its own location. These fields (Fine RTD, Relative north, Relative east and Relative altitude) are optional. All of Fine RTD, Relative north, and Relative east fields must be present, if some of them is included.

Fine RTD

This field indicates the fine RTD value between this BTS and reference BTS. It provides the 1/256 bit duration resolution to the value expressed in the corresponding Rough RTD field. This RTD value is the RTD value of TS0s (i.e. the difference in starting of TS0), not only the RTD between starts of bursts. The RTD is defined as T_BTS– T_Ref, where T_BTS is the time of the start of TS0 in the BTS in question, and T_Ref is the time of the start of the TS0 in the reference BTS. This field is optional.

Range: 0 – 255

Relative North

This field indicates the distance of the neighbor BTS from the reference BTS in north- (negative values mean south) direction. This field is optional. The units are 0,03 seconds. The used reference ellipsoid is WGS 84 ellipsoid.

Range: -200000…200000

Relative East

This field indicates the distance of the neighbor BTS from the reference BTS in east (negative values mean west) direction. This field is optional. The units are 0,03 seconds. The used reference ellipsoid is WGS 84 ellipsoid.

Range: -200000 … 200000

Relative Altitude

This field indicates the altitude of the neighbor BTS relative to the reference BTS in meters. This field is optional.

Range: -4000 .. 4000 meters

A.2.2.4 E-OTD Measurement Assistance Data for System Information List Element

This element identifies those BTSs in the System Information Neighbor List that are used for E-OTD measurements. The System Information Neighbor Lists, to which this assistance data is given, are System Information Neighbor Lists that are sent in the dedicated mode, packet idle mode, packet transfer mode, or dual transfer mode. This element helps the MS to make measurements from those neighbor BTS (even below decoding level). This element is optional in the Measure Position Request component. The presence of this element means that the MS should use the BTSs identified here to the E-OTD measurements.

The RTD and 51 multiframe offset values are calculated relative to the reference BTS. This element contains the following fields.

Number of Neighbors

This field indicates how many neighbors are included in this IE.

Range: 1-32

The following fields are repeated for the number indicated in the Number of Neighbors field.

E-OTD Neighbor present

This field indicates whether the information concerning a certain BTS in the Neighbor List is present. Altogether no more than 15 BTS can have the indication "Neighbor is included". The maximum number of BTSs in this message for whom the assistance data can be given is 16 (reference BTS and 15 neigbour BTSs). Thus the sum of total amount of E-OTD Neighbor present bits with value ‘1’ in this IE and Number of BTSs field in E-OTD Measurement Assistance Data IE can be at a maximum 15.

‘0’ Neighbor not included;

‘1’ Neighbor is included.

The following fields (BSIC, Multiframe Offset, Time Slot Sscheme and Rough RTD) are included if E-OTD neighbor present field is set to ‘1’.

BSIC

This field indicates the BSIC (Base Station Identity Code) of the particular BTS. This field is mandatory.

Range: 0 – 63

Multiframe Offset

Expected Multiframe Offset = (Multiframe Offset + Adjustment) modulo 51

Adjustment = 1 if Rough RTD – Expected OTD >= 850

Adjustment = -1 if Rough RTD – Expected OTD =< -850

Adjustment = 0 if -400 =< Rough RTD – Expected OTD =< 400

Range: 0 – 51

Usable range of Multiframe Offset value is 0 – 50. The Multiframe Offset value 51 shall not be encoded by the transmitting entity and shall be treated by the receiving entity as 0.

Time Slot Scheme

‘0’ = all time slots are 156,25 bits long;

‘1’ = time slots 0 and 4 are 157 bits long and other time slots are 156 bits long.

Rough RTD

This field indicates the RTD value between this BTS and the reference BTS. The used resolution is 1 bit. This RTD value is the RTD value of TS0s (i.e. the difference in starting of TS0), not only the RTD between starts of bursts. The RTD is defined as T_BTS– T_Ref, where T_BTS is the time of the start of TS0 in the BTS in question, and T_Ref is the time of the start of the TS0 in the reference BTS. This field is mandatory.

Range: 0 – 1250

Usable range of Rough RTD value is 0 – 1249. The RoughRTD value 1250 shall not be encoded by the transmitting entity and shall be treated by the receiving entity as 0.

Expected OTD

This field indicates the OTD value that MS is expected to measure between this BTS and reference BTS in its current estimated location. SMLC can estimate MS’s location roughly e.g. based on serving BTS coordinates, TA, and possibly some other information. The used resolution is 1 bits. This OTD value is the OTD value of TS0s (i.e. the difference in starting of TS0), not only the OTD between starts of bursts. The OTD is defined as T_BTS– T_Ref, where T_BTS is the time of the start of TS0 in the BTS in question, and T_Ref is the time of the start of the TS0 in the reference BTS. This element is Release 98 extension and it is an optional element included in Release98-Ext IE. SMLC shall send this element to MS supporting MS Assisted or MS Based E-OTD.

Range: 0 – 1250

Usable range of Expected OTD value is 0 – 1249. The Expected OTD value 1250 shall not be encoded by the transmitting entity and shall be treated by the receiving entity as 0.

Uncertainty Of Expected OTD

Expected OTD – Uncertainty < measured OTD < Expected OTD + Uncertainty.

This element is Release 98 extension and it is an optional element included in Release98-Ext IE. SMLC shall send this element to MS supporting MS Assisted or MS Based E-OTD.

Range is 0 – 7 with following encoding:

‘0’ 0 < uncertainty <= 2 bit;

‘1’ 2 < uncertainty <= 4 bit;

‘2’ 4 < uncertainty <= 8 bit;

‘3’ 8 < uncertainty <= 12 bit;

‘4’ 12 < uncertainty <= 16 bit;

‘5’ 16 < uncertainty <= 22 bit;

‘6’ 22 < uncertainty <= 30 bit;

‘7’ uncertainty > 30 bit.

NOTE: If uncertainty in MS’s location is x bits, uncertainty in Expected OTD is 2*x (in the worst case). When the uncertainty is given with value ‘7’ no upper bound exist for the uncertainty.

Fine RTD

Range: 0 – 255

Relative North

Range: -200000…200000

Relative East

Range: -200000 … 200000

Relative Altitude

This field indicates the altitude of the neighbor BTS relative to the reference BTS in meters. This field is optional.

Range: -4000 .. 4000 meters

A.2.2.4a GPS Time Assistance Measurement Request element

This component does not have any information contents. If this component is present, the MS is requested to return GPS time assistance measurements.

A.2.2.4b GPS Reference Time Uncertainty element

This element provides the accuracy of the relation GPS and GSM time in the Reference Time field in GPS Assistance Data IE. If GPS TOW is the given GPS time, then the true GPS time, corresponding to the provided GSM time as observed at the MS location, lies in the interval (GPS TOW – GPS Reference Time Uncertainty, GPS TOW + GPS Reference Time Uncertainty). An entity that supports this element shall always include it when appropriate. This means that when the element is expected but is not received, lack of support at the sender can be assumed and some implementation dependent default interpretation can then be applied.

The uncertainty r, expressed in microseconds, is mapped to a number K, with the following formula:

r = C*(((1+x)^K)-1)

with C = 0,0022 and x = 0,18. With 0 £ K £ 127, a suitably useful range between 0 and 3 second is achieved for the uncertainty, while still being able to code down to values as small as 0,3 nanoseconds. To encode any higher value of uncertainty than that corresponding in the above formula to K=127, the same value, K=127, shall also be used. The uncertainty is then coded on 7 bits, as the binary encoding of K.

Table A.1a: Example values for the GPS Reference Time Uncertainty Parameter Format

Value of K	Value of uncertainty
0	0 nanoseconds
1	0,396 nanoseconds
2	0,863 nanoseconds
–	–
50	8,64 microseconds
–	–
127	≥ 2,96 seconds

A.2.2.4c Velocity Request element

If this element is present, the MS is requested to return a velocity estimate along with the location estimate. Requesting velocity does not guarantee its delivery, if conditions support its availability and it is requested it will be provided.

A.2.2.4d GANSS Carrier-Phase Measurement Request Element

This component does not have any information contents. If this component is present, the MS is requested to return carrier phase measurements in the GANSS Measurement Information IE.

A.2.2.4e GANSS TOD – GSM Time Association Request Element

This component does not have any information contents. If this component is present, the MS is requested to return GANSS TOD – GSM time association measurements. Only either GPS Timing Assistance Measurement Request Element or GANSS TOD – GSM Time Association Measurement Request should be present in Measure Position Request.

A.2.2.4f Required Response Time

This element indicates the maximum response time that shall be allowed for the positioning request in the MS. When this element is received, the MS shall send an RRLP Measure Position Response before the required response time has elapsed.

When this element is received, the MS shall ignore the Response Time field in the Positioning Instructions element.

The Required Response Time has a value from 1 to 128 seconds.

A.2.2.4g GANSS Multi-frequency Measurement Request Element

This component does not have any information contents.

If this component is present, the MS is requested to return measurements performed on multiple GANSS signal types if the MS supports this capability. If this component is not present, the MS shall report only one signal type for each GANSS.

If SMLC has indicated supported signal types in Positioning Capability Request, the MS shall only report signals that are supported by SMLC.

A.2.2.5 Extended Reference IE

This element is mandatory in any RRLP Measure Position Request component, any RRLP Assistance Data component, any RRLP Positioning Capability Request component and any RRLP Positioning Capability response component.

NOTE: For reasons of backward compatibility, the IE is not defined for a Release 4 or earlier SMLC and would be ignored, when received, by a Release 4 or earlier MS. Additionally, other requirements associated with this IE would not be supported by a Release 4 or earlier MS or SMLC.

The Extended Reference IE contains the following elements:

SMLC code: an integer in the range 0-63 distinguishing any SMLC from other neighbour SMLCs in the same Routing Area. Each SMLC is assigned a specific SMLC ID value. The values assigned to neighbour SMLCs in the same Routing Area between which inter-NSE cell change is possible should be different.

Transaction ID: an integer in the range 0-262143 distinguishing different RRLP transactions in different MSs currently being served by the same SMLC. An SMLC shall assign a different transaction ID to each currently open RRLP transaction for positioning and assistance data delivery among all target MSs. When any RRLP transaction for any MS is completed in the SMLC (e.g. the MS has sent a correctly formatted RRLP Measure Position Response or Assistance Data Ack.) or if the transaction is aborted (e.g. SMLC timeout on an RRLP response), the associated transaction ID value shall become free and may be later assigned to a new RRLP transaction by the SMLC. When any transaction ID value becomes free, an SMLC should attempt to wait for at least 128 seconds (the maximum defined RRLP response time from an MS) before reassigning the same value.