Providing estimated accuracy of mobile station synchronization and mobile station transmission offset to the network
10609674 · 2020-03-31
Assignee
Inventors
- Stefan Eriksson Löwenmark (Färentuna, SE)
- Nicklas Johansson (Brokind, SE)
- John Walter Diachina (Garner, NC)
Cpc classification
H04W72/21
ELECTRICITY
G01S5/06
PHYSICS
H04W64/00
ELECTRICITY
H04L5/0053
ELECTRICITY
G01S5/0036
PHYSICS
G01S5/10
PHYSICS
H04W64/006
ELECTRICITY
H04W56/0045
ELECTRICITY
International classification
H04W64/00
ELECTRICITY
G01S5/00
PHYSICS
G01S5/06
PHYSICS
G01S5/10
PHYSICS
Abstract
A mobile station (MS), a base station subsystem (BSS), and various methods are described herein that enable a positioning node (e.g., Serving Mobile Location Center (SMLC)) to improve the accuracy of estimating a position of the mobile station.
Claims
1. A base station subsystem (BSS) configured to interact with a mobile station and a Serving Mobile Location Center (SMLC), wherein the BSS includes a base transceiver station (BTS), the BSS comprising: a processor; and, a memory that stores processor-executable instructions, wherein the processor interfaces with the memory to execute the processor-executable instructions, whereby the BSS is operable to: transmit, to the mobile station, a multilateration request; and, receive, from the mobile station, a Radio Link Control (RLC) data block that includes at least (i) a Temporary Logical Link Identifier (TLLI) of the mobile station, (ii) an estimated mobile station synchronization accuracy, and (iii) a mobile station transmission offset.
2. The BSS of claim 1, wherein the BSS is further operable to: obtain a timing advance (TA) estimation for the mobile station calculated by the BTS based on the received RLC data block; adjust the TA estimation according to the mobile station transmission offset; and transmit, to the SMLC, the adjusted TA estimation, the estimated mobile station synchronization accuracy, and a BTS TA accuracy.
3. The BSS of claim 2, wherein the BSS performs the adjust operation per the following: the adjusted TA estimation (TA.sub.adjusted)=the TA estimation (TA.sub.estimated) minus the mobile station transmission offset.
4. The BSS of claim 1, wherein the RLC data block further includes a Source Identity of the BSS.
5. The BSS of claim 1, wherein the RLC data block further includes a length indicator to indicate a presence of the estimated mobile station synchronization accuracy and the mobile station transmission offset.
6. A method in a base station subsystem (BSS) configured to interact with a mobile station and a Serving Mobile Location Center (SMLC), wherein the BSS includes a base transceiver station (BTS), the method comprising: transmitting, to the mobile station, a multilateration request; and, receiving, from the mobile station, a Radio Link Control (RLC) data block that includes at least (i) a Temporary Logical Link Identifier (TLLI) of the mobile station, (ii) an estimated mobile station synchronization accuracy, and (iii) a mobile station transmission offset.
7. The method of claim 6, further comprising: obtaining a timing advance (TA) estimation for the mobile station calculated by the BTS based on the received RLC data block; adjusting the TA estimation according to the mobile station transmission offset; and transmitting, to the SMLC node, the adjusted TA estimation, the estimated mobile station synchronization accuracy, and a BTS TA accuracy.
8. The method of claim 7, wherein the adjusting step is performed as follows: the adjusted TA estimation (TA.sub.adjusted)=the TA estimation (TA.sub.estimated) minus the mobile station transmission offset.
9. The method of claim 6, wherein the RLC data block further includes a Source Identity of the BSS.
10. The method of claim 6, wherein the RLC data block further includes a length indicator to indicate a presence of the estimated mobile station synchronization accuracy and the mobile station transmission offset.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) A more complete understanding of the present disclosure may be obtained by reference to the following detailed description when taken in conjunction with the accompanying drawings:
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DETAILED DESCRIPTION
(15) A discussion is provided herein first to describe an exemplary wireless communication network 200 that includes multiple BSSs 202.sub.1, 202.sub.2, 202.sub.3, a mobile station 204, and multiple SMLCs 206.sub.1 and 206.sub.2 configured to improve the accuracy in estimating a position of the mobile station 204 in accordance with an embodiment of the present disclosure (see
(16) Exemplary Wireless Communication Network 200
(17) Referring to
(18) The wireless communication network 200 includes the BSSs 202.sub.1, 202.sub.2, 202.sub.3 (which are basically wireless access nodes 202.sub.1, 202.sub.2, 202.sub.3, RAN nodes 202.sub.1, 202.sub.2, 202.sub.3, wireless access points 202.sub.1, 202.sub.2, 202.sub.3) which can provide network access to the mobile station 204. Each BSS 202.sub.1, 202.sub.2, 202.sub.3 includes one or more BTSs 210.sub.1, 210.sub.2, 210.sub.3 and a BSC 212.sub.1, 212.sub.2, 212.sub.3. The BSSs 202.sub.1, 202.sub.2, 202.sub.3 are connected to the core network 208 and, in particular, to the CN node 207 (e.g., SGSN 207). The core network 208 is connected to an external packet data network (PDN) 219, such as the Internet, and a server 213 (only one shown). The mobile station 204 may communicate with one or more servers 213 (only one shown) connected to the core network 208 and/or the PDN 219.
(19) The mobile station 204 may be referred to generally as an end terminal (user) that attaches to the wireless communication network 200, and may refer to either a Machine Type Communications (MTC) device (e.g., a smart meter) or a non-MTC device. Further, the term mobile station is generally intended to be synonymous with the term mobile device, wireless device, User Equipment, or UE, as that term is used by 3GPP, and includes standalone mobile stations, such as terminals, cell phones, smart phones, tablets, Internet of Things (IoT) devices, cellular IoT devices, and wireless-equipped personal digital assistants, as well as wireless cards or modules that are designed for attachment to or insertion into another electronic device, such as a personal computer, electrical meter, etc. . . . .
(20) The mobile station 204 may include a transceiver circuit 214 for communicating with the BSSs 202.sub.1, 202.sub.2, 202.sub.3 (RAN nodes 202.sub.1, 202.sub.2, 202.sub.3), and a processing circuit 216 for processing signals transmitted from and received by the transceiver circuit 214 and for controlling the operation of the mobile station 204. The transceiver circuit 214 may include a transmitter 218 and a receiver 220, which may operate according to any standard, e.g., the GSM/EDGE standard, and the EC-GSM standard. The processing circuit 216 may include a processor 222 and a memory 224 for storing program code for controlling the operation of the mobile station 204. The program code may include code for performing the procedures as described hereinafter.
(21) Each BTS 210.sub.1, 210.sub.2, 210.sub.3 may include a transceiver circuit 226.sub.1, 226.sub.2, 226.sub.3 for communicating with the mobile station 204 (typically multiple mobile stations 204only one shown for clarity) and their respective BSC 212.sub.1, 212.sub.2, 212.sub.3, a processing circuit 228.sub.1, 228.sub.2, 228.sub.3 for processing signals transmitted from and received by the transceiver circuit 226.sub.1, 226.sub.2, 226.sub.3 and for controlling the operation of the corresponding BTS 210.sub.1, 210.sub.2, 210.sub.3. The transceiver circuit 226.sub.1, 226.sub.2, 226.sub.3 may include a transmitter 230.sub.1, 230.sub.2, 230.sub.3 and a receiver 232.sub.1, 232.sub.2, 232.sub.3, which may operate according to any standard, e.g., the GSM/EDGE standard, and the EC-GSM standard. The processing circuit 228.sub.1, 228.sub.2, 228.sub.3 may include a processor 234.sub.1, 234.sub.2, 234.sub.3, and a memory 236.sub.1, 236.sub.2, 236.sub.3 for storing program code for controlling the operation of the corresponding BTS 210.sub.1, 210.sub.2, 210.sub.3. The program code may include code for performing the procedures as described hereinafter.
(22) Each BSC 212.sub.1, 212.sub.2, 212.sub.3 may include a transceiver circuit 238.sub.1, 238.sub.2, 238.sub.3 for communicating with their respective BTS 210.sub.1, 210.sub.2, 210.sub.3 and SMLC 206.sub.1, 206.sub.2, a processing circuit 240.sub.1, 240.sub.2, 240.sub.3 for processing signals transmitted from and received by the transceiver circuit 238.sub.1, 238.sub.2, 238.sub.3 and for controlling the operation of the corresponding BSC 212.sub.1, 212.sub.2, 212.sub.3, and a network interface 242.sub.1, 242.sub.2, 242.sub.3 for communicating with the SGSN 207 part of the core network 208. The transceiver circuit 238.sub.1, 238.sub.2, 238.sub.3 may include a transmitter 244.sub.1, 244.sub.2, 244.sub.3 and a receiver 246.sub.1, 246.sub.2, 246.sub.3, which may operate according to any standard, e.g., the GSM/EDGE standard (in this example), and the EC-GSM standard. The processing circuit 240.sub.1, 240.sub.2, 240.sub.3 may include a processor 248.sub.1, 248.sub.2, 248.sub.3, and a memory 250.sub.1, 250.sub.2, 250.sub.3 for storing program code for controlling the operation of the corresponding BSC 212.sub.1, 212.sub.2, 212.sub.3. The program code may include code for performing the procedures as described hereinafter. Note: for purposes of the discussion herein, it should be appreciated that the BSS 202.sub.1, 202.sub.2, 202.sub.3 circuitry can be considered to be the same circuitry as BSC 212.sub.1, 212.sub.2, 212.sub.3 (it should be appreciated that a BSS comprises a BSC and a BTS according to well-known prior art, so when there is a discussion herein about a BSS performing certain functions, it typically means the BSC performing those functions unless it is specifically mentioned that the BTS is performing a function).
(23) The CN node 207 (e.g., SGSN 207, Mobility Management Entity (MME) 207) may include a transceiver circuit 252 for communicating with the BSSs 202.sub.1, 202.sub.2, 202.sub.3, a processing circuit 254 for processing signals transmitted from and received by the transceiver circuit 252 and for controlling the operation of the CN node 207, and a network interface 257 for communicating with the PDN 219 or the server 213. The transceiver circuit 252 may include a transmitter 256 and a receiver 258, which may operate according to any standard, e.g., the GSM/EDGE standard (in this example), and the EC-GSM standard. The processing circuit 254 may include a processor 260 and a memory 262 for storing program code for controlling the operation of the CN node 207. The program code may include code for performing the procedures as described hereinafter.
(24) Techniques for Improving Accuracy of Mobile Station's Estimated Position
(25) Brief Description
(26) In accordance with an embodiment of the present disclosure, the MS 204 when synchronizing to a BTS 210.sub.1, 210.sub.2, 210.sub.3 (three shown) also estimates the accuracy 264.sub.1, 264.sub.2, 264.sub.3 by which it has synchronized to the BTS 210.sub.1, 210.sub.2, 210.sub.3. Further, the MS 204 also estimates a MS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3 with which it is able to time its uplink transmissions to the BTS 210.sub.1, 210.sub.2, 210.sub.3. The MS 204 reports (e.g., in an uplink Radio Link Control (RLC) data block 270.sub.1, 270.sub.2, 270.sub.3) the estimated synchronization accuracy 264.sub.1, 264.sub.2, 264.sub.3 and the MS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3 associated with the respective BTS 210.sub.1, 210.sub.2, 210.sub.3 to the network (e.g., BSS 202.sub.1, 202.sub.2, 202.sub.3). The BSS 202.sub.1, 202.sub.2, 202.sub.3 (BTS 210.sub.1, 210.sub.2, 210.sub.3) adjusts its estimated TA 271.sub.1, 271.sub.2, 272.sub.3 for the MS 204 according to the indicated MS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3 and then forwards in a BSSMAP-LE CONNECTION ORIENTED INFORMATION message 275.sub.1, 275.sub.2, 275.sub.3 (for example) the Adjusted Estimated Timing Advance 285.sub.1, 285.sub.2, 285.sub.3 and the estimated MS synchronization accuracy 264.sub.1, 264.sub.2, 264.sub.3 to the serving SMLC 206.sub.1 along with a corresponding BTS Timing Advance Accuracy 273.sub.1, 273.sub.2, 273.sub.3. All three of these values 264.sub.1, 264.sub.2, 264.sub.3, 273.sub.1, 273.sub.2, 273.sub.3, 285.sub.1, 285.sub.2, 285.sub.3 are taken into account by the serving SMLC 206.sub.1 when estimating the accuracy of the estimated position of the MS 204. Alternatively, in another embodiment of the present disclosure in order to address scenarios where the MS 204 is not able to provide an estimate of the MS synchronization accuracy 264.sub.1 and the MS Transmission Offset 265.sub.1 to the serving SMLC 206.sub.1, instead there is provided to the serving SMLC 206.sub.1 an a priori understanding of the MS Transmission Timing Accuracy capability, by having the serving BSS 202.sub.1 use a field 266 (MS Transmission Timing Accuracy field 266) which can be added to a MS Radio Access Capability Information Element (IE) 267 and sent to the serving SMLC 206.sub.1 (see 3GPP TS 24.008 v14.1.0 which discloses the traditional MS Radio Access Capability IE without the new MS Transmission Timing Accuracy field 266the contents of which are incorporated herein by reference). The MS Transmission Timing Accuracy field 266 indicates (a) the worst case accuracy (guaranteed minimum accuracy) with which the MS 204 is able to estimate the timing of the BTS 210.sub.1 according to signals received from the BTS 210.sub.1 and (b) the worst case MS Transmission Offset 265.sub.1. It is further proposed in yet another embodiment of the present disclosure that the serving BSS 202.sub.1 passes either the complete MS Radio Access Capability IE 267 or the MS Transmission Timing Accuracy field 266 in a BSSMAP-LE PERFORM-LOCATION-REQUEST Protocol Data Unit (PDU) 269 to the serving SMLC 206.sub.1 prior to the serving SMLC 206.sub.1 triggering multilateration for the MS 204 (e.g., sending the MS 204 a multilateration request 272).
(27) Moreover, in order for the serving SMLC 206.sub.1 to be able to accurately assess the overall MS positioning accuracy, it could also utilize a BTS TA accuracy 271.sub.1, 271.sub.2, 271.sub.3. To this end, it is therefore proposed in another embodiment of the present disclosure to add a means for the BSS 202.sub.1, 202.sub.2, 202.sub.3 to indicate its BTS's TA estimation capability 273.sub.1, 273.sub.2, 273.sub.3 to the serving SMLC 206.sub.1 in a BSSMAP-LE CONNECTION ORIENTED INFORMATION message 275.sub.1, 275.sub.2, 275.sub.3 either as a new IE or as part of the BSSLAP APDU (note 1: BSS 202.sub.1 transmits its BTS TA estimation capability directly to the serving SMLC 206.sub.1 within a BSSMAP-LE CONNECTION ORIENTED INFORMATION message 275.sub.1; the BSS 202.sub.2 first transmits its BTS TA estimation capability to the BSS 202.sub.1 using inter-BSS communication, then the BSS 202.sub.1 transmits the BSSMAP-LE CONNECTION ORIENTED INFORMATION message 275.sub.2 to the serving SMLC 206.sub.1 (this signaling is not shown in
(28) Detailed Description
(29) As part of its procedure to time the uplink transmission to the BTS 210.sub.1, 210.sub.2, 210.sub.3 according to signals received from the BTS 210.sub.1, 210.sub.2, 210.sub.3, the MS 204 first synchronizes to the network 200 (BTS 210.sub.1, 210.sub.2, 210.sub.3). In the synchronization process, the MS 204 estimates the synchronization accuracy 264.sub.1, 264.sub.2, 264.sub.3 by which it has synchronized to the BTS 210.sub.1, 210.sub.2, 210.sub.3 (note: the MS 204 will estimate a separate synchronization accuracy 264.sub.1, 264.sub.2, 264.sub.3 for each BTS 210.sub.1, 210.sub.2, 210.sub.3). For example, the MS 204 can estimate the synchronization accuracy 264.sub.1, 264.sub.2, 264.sub.3 by performing multiple synchronizations and measurements of the timing of the BTS 210.sub.1, 210.sub.2, 210.sub.3 and estimating the variance between these measurements. For instance, if N measurements of the timing are denoted t.sub.i, i=1, . . . , N, the variance of the individual measurement can be estimated using the well-known formula for unbiased sample variance:
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(31) where
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(33) Further, if the MS 204 finally estimates the timing of the BTS 210.sub.1, 210.sub.2, 210.sub.3 as the mean of the individual measurements (i.e., by
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(35) When synchronization is completed, the MS 204 will access the cell. However, the uplink transmission of the MS 204 when accessing the cell may not be perfectly time aligned with the timing of the signals from the BTS 210.sub.1, 210.sub.2, 210.sub.3 as estimated during synchronization due to limitations in the design of the MS 204. For example, this limitation in the design of the MS 204 may be due to the internal time base of the MS 204 (to which transmissions must be time aligned) which may not be perfectly aligned with the estimated timing of the BTS transmissions. The internal time base used for uplink transmissions may be somewhat arbitrary as to when its corresponding uplink transmission opportunities (see upward pointing dashed arrows in
(36) In other words, by e.g., the BSS 202.sub.1, 202.sub.2, 202.sub.3 (BTS 210.sub.1, 210.sub.2, 210.sub.3) not having access to MS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3 applicable when the MS 204 performed the MTA procedure in a given cell, there will be a forced misalignment of uplink transmissions that the BSS 202.sub.1, 202.sub.2, 202.sub.3 (BTS 210.sub.1, 210.sub.2, 210.sub.3) will not be able to take into account. This will then contribute to the total TA estimation error (i.e., the BSS 202.sub.1, 202.sub.2, 202.sub.3 (BTS 210.sub.1, 210.sub.2, 210.sub.3) will determine a value for the Estimated Timing Advance 271.sub.1, 271.sub.2, 271.sub.3 but will not be able to determine a value for the Adjusted Estimated Timing Advance 285.sub.1, 285.sub.2, 285.sub.3). See FIG. 3 where this problem is illustrated with the assumption that the uplink transmission opportunities associated with the used internal time base are spaced symbol apart. Based on signals from the BTS 210.sub.1, 210.sub.2, 210.sub.3 (i.e., BTS true timing), the MS 204 estimates the downlink (DL) timing denoted as MS estimated DL timing. Now, due to limitations in the MS 204 (i.e., the internal time base imposed on all uplink transmissions) there is a difference between the MS Nominal UL Transmission opportunity (e.g., determined according to the MS estimated DL timing+3 time slot offset for the uplink) and the MS Selected Transmission opportunity (i.e., the closest internal time base uplink transmission opportunity which may occur either before or after the MS Nominal Transmission opportunity), denoted MS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3. The present disclosure addresses this problem by having the MS 204 estimate and transmit the MS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3 to each BTS 210.sub.1, 210.sub.2, 210.sub.3 as information included in the respective RLC data block 270.sub.1, 270.sub.2, 270.sub.3.
(37) Each BTS 210.sub.1, 210.sub.2, 210.sub.3 will perform a TA estimation 271.sub.1, 271.sub.2, 271.sub.3 based on the signal sent by the MS 204 (e.g., an access request received on the EC-RACH or an uplink RLC data block received on an EC-PDTCH). In this process, the BTS 210.sub.1, 210.sub.2, 210.sub.3 will estimate the accuracy by which it is able to measure the timing of signals received from the MS 204. From the accuracy (BTS timing advance accuracy 271.sub.1, 271.sub.2, 271.sub.3) estimated by the BTS 210.sub.1, 210.sub.2, 210.sub.3 and the information (MS synchronization accuracy 264.sub.1, 264.sub.2, 264.sub.3 and MS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3) provided by the MS 204, a total accuracy of the TA estimation is derived. The BSS 202.sub.1, 202.sub.2, 202.sub.3 (BTS 210.sub.1, 210.sub.2, 210.sub.3) can further use the MS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3 to directly compensate the Estimated Timing Advance (TA.sub.estimated) value 271.sub.1, 271.sub.2, 271.sub.3 as this is a known error in the MS 204, i.e., Adjusted Estimated Timing Advance (TA.sub.adjusted)=TA.sub.estimatedMS Transmission Offset. Either of these separate accuracies or the total accuracy (i.e., the BTS processes the values of the BTS Timing Advance Accuracy 271.sub.1, 271.sub.2, 271.sub.3 and the MS Sync Accuracy 264.sub.1, 264.sub.2, 264.sub.3 to arrive at a value for the overall Timing Advance Accuracy for the corresponding cell) is delivered by the serving BSS 202.sub.1 to the serving SMLC node 206.sub.1. The serving SMLC node 206.sub.1 combines accuracy estimates of TA estimates from multiple BTSs 210.sub.1, 210.sub.2, 210.sub.3 to derive an estimate of the accuracy of the positioning of the MS 204.
(38) It shall be noted to anyone skilled in the art that the principles described in the embodiments below also are applicable to other Radio Access technologies such as Long Term Evolution (LTE), Universal Mobile Telephony System (UMTS), Narrow Band Internet of Things (NB-IoT) and Enhanced Machine Type Communications (eMTC) where a communication device (a) estimates and adjusts (synchronizes) to the downlink timing of the network and (b) the uplink transmission of the communication device when accessing the network may not be perfectly time aligned with the timing of the signals from the network as estimated during synchronization.
(39) In a first embodiment of the present disclosure, it is proposed, in addition to the Temporary Logical Link Identifier (TLLI) 274 (or other MS identity) of the MS 204, to also include the estimated MS synchronization accuracy 264.sub.1 as well as the MS Transmission Offset 265.sub.1 respectively in two new fields called MS Sync Accuracy field 278 and the MS Transmission Offset field 290 in the Radio Link Control (RLC) data block 270.sub.1 transmitted by the MS 204 on an uplink Temporary Block Flow (TBF) established in response to an access request 272 indicating Multilateration. In order for the BSS 202.sub.1 (BTS 210.sub.1) to extract the estimated MS synchronization accuracy 264.sub.1 and the MS Transmission Offset 265.sub.1 from the uplink RLC data block 270.sub.1, it is proposed that the MS 204 use a reserved length indicator 276, e.g., a length indicator 276 of value 122 in the RLC data block 270.sub.1 (note that any of the unused length indicators may be used). Length indicators are used to delimit upper layer PDU but may also be used to indicate the presence of additional information within the RLC data block. One example is the length indicator with a value 125, which indicates the presence of dynamic timeslot reduction control information which shall be included after the last Upper Layer PDU (see 3GPP TS 44.060 V13.3.0 (2016 September)the contents of which are incorporated by reference herein). In the case of Multilateration, it is proposed that a Length Indicator 276 of value 122 be used in the RLC data block 270.sub.1 by the MS 204 to indicate the presence of the MS synchronization accuracy field 278 (which includes the estimated MS synchronization accuracy 264.sub.1) and the MS Transmission Offset field 290 (which includes the MS Transmission Offset 265.sub.1) in the first octet immediately following the Length Indicator 276.
(40) In a second embodiment, it is proposed, in addition to the TLLI 274 (or other MS identity) of the MS 204 and the Source Identity 280 of the Serving BSS 202.sub.1, to also include the estimated MS synchronization accuracy 264.sub.2, 264.sub.3 and the estimated uplink MS Transmission Offset 265.sub.2, 265.sub.3 in the RLC data blocks 270.sub.2, 270.sub.3 transmitted by the MS 204 on an uplink TBF established in response to an access request 272 indicating Multilateration. In order for the BSSs 202.sub.2, 202.sub.3 (BTSs 210.sub.2, 210.sub.3) to extract the estimated MS synchronization accuracy 264.sub.2, 264.sub.3 and the MS Transmission Offset 265.sub.2, 265.sub.3 from the uplink RLC data blocks 270.sub.2, 270.sub.3, it is proposed that the MS 204 uses a reserved length indicator 276, e.g., a length indicator 276 of value 122 within the RLC data blocks 270.sub.2, 270.sub.3. In the case of Multilateration, it is proposed that a Length Indicator 276 of value 122 is used in the RLC data blocks 270.sub.2, 270.sub.3 by the MS 204 to indicate the presence of the Source Identity field 281, MS synchronization accuracy field 278, and the MS Transmission Offset field 290 in the five octets immediately following the Length Indicator 276 (four octets for the Source Identity field 281, octet for the MS synchronization accuracy field 278, and a octet for the MS Transmission Offset field 290). The assumption of using four octets for the Source Identity field 281 can be seen as valid if it is always sufficient to provide two octets of Location Area Code (LAC) and two octets of Cell ID information for the source identity (i.e., if it can be assumed that only cells belonging to the same Public Land Mobile Network (PLMN) are used for positioning). However, the Source Identity field 281 could alternatively comprise Mobile Country Code (MCC)+Mobile Network Code (MNC)+LAC+Cell ID (i.e., a total of 7 octets) in order to address the case where knowledge of PLMN ID (MCC+MNC) is needed to forward the derived TA information 264.sub.2, 264.sub.3 and associated Cell ID information 280 from a non-serving BSS 202.sub.2 and 202.sub.3 to the serving BSS 202.sub.1. For possible codings of the MS synchronization accuracy field 278 and the MS Transmission Offset field 290, see
(41) In either the first embodiment or the second embodiment, it is proposed that the BSS 202.sub.1, 202.sub.2, 202.sub.3 (BTS 210.sub.1, 210.sub.2, 210.sub.3) or the SMLC 206.sub.1 uses the reported MS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3 to compensate the Estimated Timing Advance (TA.sub.estimated) value 271.sub.1, 271.sub.2, 271.sub.3 to arrive at an Adjusted Estimated Timing Advance (TA.sub.adjusted) value 285.sub.1, 285.sub.2, 285.sub.3 according to TA.sub.adjusted=TA.sub.estimatedMS Transmission Offset 265.sub.1, 265.sub.2, 265.sub.3.
(42) In a third embodiment, in order to address a scenario when there is no assessment of the MS synchronization accuracy 264.sub.1 and the MS Transmission Offset 265.sub.1 from the MS 204 as the MTA procedure is performed in each cell, it is proposed to add means for the serving BSS 202.sub.1 to pass a new field called the MS Transmission Timing Accuracy Capability IE 266 (which includes a total MS transmission accuracy derived from a worst case MS synchronization accuracy and a worst case MS Transmission Offset) to the serving SMLC 206.sub.1 in the BSSMAP-LE PERFORM LOCATION REQUEST message 269 sent from the serving BSS 202.sub.1 to the serving SMLC 206.sub.1. In this case, the serving BSS 202.sub.1 obtains the information carried in MS Transmission Timing Accuracy Capability IE 266 from the MS Radio Access Capability Information Element (IE) 267 received from the SGSN 207 when the SGSN 207 commands the BSS 202.sub.1 to perform the positioning procedure.
(43) In a fourth embodiment, in order for the serving SMLC 206.sub.1 to know the overall accuracy of the estimation of the TA 271.sub.1, 271.sub.2, 271.sub.3, it is proposed to add means for the BSS 202.sub.1, 202.sub.2, 202.sub.3 (BTS 210.sub.1, 210.sub.2, 210.sub.3) to indicate an overall TA estimation accuracy to the serving SMLC 206.sub.1 in the BSSMAP-LE CONNECTION ORIENTED INFORMATION message 275.sub.1, 275.sub.2, 275.sub.3, either as a new IE or as part of the BSSLAP APDU.
(44) Basic Functionalities-Configurations of the MS 204 and the BSS 202.sub.1, 202.sub.2, 202.sub.3
(45) Referring to
(46) Referring to
(47) As those skilled in the art will appreciate, the above-described modules 1102, 1104, and 1106 of the mobile station 204 may be implemented separately as suitable dedicated circuits. Further, the modules 1102, 1104, and 1106 can also be implemented using any number of dedicated circuits through functional combination or separation. In some embodiments, the modules 1102, 1104, and 1106 may be even combined in a single application specific integrated circuit (ASIC). As an alternative software-based implementation, the mobile station 204 may comprise a memory 224, a processor 222 (including but not limited to a microprocessor, a microcontroller or a Digital Signal Processor (DSP), etc.) and a transceiver 214. The memory 224 stores machine-readable program code executable by the processor 222 to cause the mobile station 204 to perform the steps of the above-described method 1000.
(48) Referring to
(49) Referring to
(50) As those skilled in the art will appreciate, the above-described modules 1302, 1304, 1306, 1308, and 1310 of the BSS 202.sub.1 may be implemented separately as suitable dedicated circuits. Further, the modules 1302, 1304, 1306, 1308, and 1310 can also be implemented using any number of dedicated circuits through functional combination or separation. In some embodiments, the modules 1302, 1304, 1306, 1308, and 1310 may be even combined in a single application specific integrated circuit (ASIC). As an alternative software-based implementation, the BSS 202.sub.1 may comprise a memory 250.sub.1, a processor 248.sub.1 (including but not limited to a microprocessor, a microcontroller or a Digital Signal Processor (DSP), etc.) and a transceiver 238.sub.1. The memory 250.sub.1 stores machine-readable program code executable by the processor 248.sub.1 to cause the BSS 202.sub.1 to perform the steps of the above-described method 1200. Note: the other BSSs 202.sub.2 and 202.sub.3 may be configured the same as BSS 202.sub.1.
(51) In view of the foregoing disclosure, it will be readily appreciated that it is beneficial for the serving SMLC 206.sub.1 to receive cell specific timing advance information that is supplemented with MS Synchronization Accuracy information 264.sub.1, 264.sub.2, 264.sub.3 that indicates the guaranteed minimum accuracy with which the MS 204 is able to synchronize to signals received from the BTS 210.sub.1, 210.sub.2, 210.sub.3 and time its uplink transmissions accordingly. It should also be appreciated that another problem addressed herein by the disclosed techniques is that the possible timing of MS 204 uplink transmissions may be restricted by the MS implementation, e.g., by an internal time base to which uplink transmissions made by the MS 204 must be aligned, and whose phase cannot be adjusted. This means that MS 204 implementations that force uplink transmissions to align with such an internal time base will commonly result is an offset in the timing of the MS transmissions, relative to (case a) the estimated timing of the signals received from the BTS 210.sub.1, 210.sub.2, 210.sub.3 for the case of e.g., an access attempt sent on the Random Access Channel (RACH)/Extended Coverage-Random Access Channel (EC-RACH) or (case b) the timing advance information sent from a BSS 202.sub.1, 202.sub.2, 202.sub.3 to an MS 204 in response to e.g., an access request sent by the MS 204 on the RACH/EC-AGCH. In other words, MS uplink transmissions will not be made according to the MS Synchronization Accuracy 264.sub.1, 264.sub.2, 264.sub.3 alone per (case a) according to the MS Synchronization Accuracy 264.sub.1, 264.sub.2, 264.sub.3 plus an indicated timing advance as per (case b), but may also be subject to an offset, herein called the MS Transmission Offset 265.sub.1,265.sub.2, 265.sub.3, that the MS 204 is aware of but unable to correct. Further, the BTS 210.sub.1, 210.sub.2, 210.sub.3 (or the SMLC 206.sub.1) can use the MS Transmission Offset 265.sub.1, 265.sub.2, 265 to directly compensate the Estimated BTS Timing Advance value 271.sub.1, 271.sub.2, 271.sub.3 in order to derive a more accurate value referred to herein as an Adjusted BTS Estimated Timing Advance value 285.sub.1, 285.sub.2, 285.sub.3. As such it will be beneficial for the BTS 210.sub.1, 210.sub.2, 210.sub.3 to receive MS Transmission Offset information 265.sub.1, 265.sub.2, 265.sub.3 from the MS 204 whenever it performs the positioning procedure in a given cell, thereby allowing e.g., the BTS 210.sub.1, 210.sub.2, 210.sub.3 to adjust its Estimated Timing Advance 271.sub.1, 271.sub.2, 271.sub.3 for that MS 204 so that an Adjusted Estimated Timing Advance 285.sub.1, 285.sub.2, 285.sub.3 can be determined and relayed to the serving SMLC 206.sub.1.
(52) Those skilled in the art will appreciate that the use of the term exemplary is used herein to mean illustrative, or serving as an example, and is not intended to imply that a particular embodiment is preferred over another or that a particular feature is essential. Likewise, the terms first and second, and similar terms, are used simply to distinguish one particular instance of an item or feature from another, and do not indicate a particular order or arrangement, unless the context clearly indicates otherwise. Further, the term step, as used herein, is meant to be synonymous with operation or action. Any description herein of a sequence of steps does not imply that these operations must be carried out in a particular order, or even that these operations are carried out in any order at all, unless the context or the details of the described operation clearly indicates otherwise.
(53) Of course, the present disclosure may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. One or more of the specific processes discussed above may be carried out in a cellular phone or other communications transceiver comprising one or more appropriately configured processing circuits, which may in some embodiments be embodied in one or more application-specific integrated circuits (ASICs). In some embodiments, these processing circuits may comprise one or more microprocessors, microcontrollers, and/or digital signal processors programmed with appropriate software and/or firmware to carry out one or more of the operations described above, or variants thereof. In some embodiments, these processing circuits may comprise customized hardware to carry out one or more of the functions described above. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.
(54) Although multiple embodiments of the present disclosure have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it should be understood that the invention is not limited to the disclosed embodiments, but instead is also capable of numerous rearrangements, modifications and substitutions without departing from the present disclosure that as has been set forth and defined within the following claims.