Shu Wang, Jungwon Min, Li-Hsiang Sun, LGE

Transcription

1 TITLE: Extended AccessParameters Message for Enhanced LBS Support SOURCE: Shu Wang, Jungwon Min, Li-Hsiang Sun, LGE ABSTRACT: This contribution proposes extended access channel parameters on HRPD for enhanced LBS support RECOMMENDATION: Review and adopt 2008 LG Electronics, Inc. LG Electronics, Inc. grants a free, irrevocable license to 3GPP2 and its Organizational Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner's name any Organizational Partner's standards publication even though it may include all or portions of this contribution; and at the Organizational Partner's sole discretion to permit others to reproduce in whole or in part such contribution or the resulting Organizational Partner's standards publication. LG Electronics, Inc. is also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner s standard which incorporates this contribution. This document has been prepared by LG Electronics, Inc. to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on LG Electronics, Inc.. LG Electronics, Inc. specifically reserves the right to amend or modify the material contained herein and nothing herein shall be construed as conferring or offering licenses or rights with respect to any intellectual property of LG Electronics Inc other than provided in the copyright statement above.

2 Outline cdma2000 positioning technologies Tradeoffs between forward link and reverse link positioning methods Reverse link position approaches: TOA and TDOA EV-DO access probe and AccessParameters message Extended EV-DO AccessParameters message

3 cdma2000 Positioning Technologies Enhanced Forward Link Trilateration (EFLT) EFLT uses existing pilot signal measurement message (PSMM) from mobile to BS. The PSMM is relayed through MSC to PDE. EFLT is typically used as a backup for non-aflt or non-agps phones. Advanced Forward Link Trilateration (AFLT) AFLT is a forward link TDOA-based technique. AT measures the difference of time arrival of pilots from multiple base station. AT uses IS-801 message to send the measurements through AN to PDE. AFLT has about 1/8 chip reporting resolution. AFLT is commonly used as a hybrid with A-GPS. Assisted GPS GPS positioning is assisted by network. Assisted data can be transmitted using IS-801 message.

4 Forward Link or Reverse Link Both EFLT and AFLT were designed primarily for cdma2000 1X. They are AT-assisted approaches, where AT needs to measure the forward link pilots from multiple ANs and send them to PDE. There are certain tradeoffs between forward and reverse link approaches. Most forward link approaches require ATs to be explicitly involved into positioning procedures. The power of FL pilot channels is strong. AT has limited resources. No support for EV-DO. Reverse link approaches impose less burden on the AT side. AN usually has enough resources for positioning. Low latency with no feedback channel necessary. Flexible and standards-independent. Additional support for reverse link positioning is important for evolving cdma2000. Different LBS has different positioning quality and cost requirements.

5 Reverse Link Time (Difference) of Arrival The time (difference) of arrival (TOA/TDOA) of access bursts in the access channel from an AT is tracked by the multiple BTS s or LMUs (location measurement units). The location estimation schemes are similar to cdma2000 AFLT. In TOA approach, one TOA measurement by one BTS or LMU determines a circle. In TDOA approach, the difference in TOA measurements by two different BTS or LMUs determines a hyperbola. AT can be requested to send out random access bursts for positioning. New access probe and access parameter message are proposed for facilitating RL-based positioning procedure.

6 Proposed Access Probe Enhancements for LBS Preamble only access probe Preamble: 4 slots, 1~15 frames Payload: 0 Extended access probe with payload Preamble: 4 slots, 1~15 frames Payload: 1~CapsuleLengthMax frames Extended access probe offset. It will be sent with extended access probe offsets. The possible access probe offset values include 16 slots, 32 slots, 48 slots, 64 slots, 80 slots, 96 slots, 112 slots, 128 slots.

7 EV-DO Access Channel and Access Probe Access channel is usually used by the AT to initiate communication with the AN or to respond to an AT directed message. Access channel consists of pilot channel and data channel. The default data rate of the access channel is 9.6 kbps Access probe consists of preamble and one or more access channel physical layer packet. Only pilot channel during the preamble transmission Pilot and data channel during the physical layer packet transmission On the access channel, AT sends a series of access probes until it receives a response from AN or the timer expires.

8 AccessParameters and Extension

9 Access Probe Configuration EnhancedAccessP arameterincluded ExtendedAccessP arameterincluded PreambleO nlyenabled Comments Default N/A N/A N/A Preamble: PreambleLength frames Payload: 1~CapsuleLengthMax frames Enhanced 1 N/A N/A Preamble: 4 or 16 slots Payload: 1~CapsuleLengthMax frames Extended Preamble: 4 slots if PreambleLengthEx==0. PreambleLengthEx frames, otherwise Payload: 1~CapsuleLengthMax frames Preamble- Only Preamble: 4 slots if PreambleLengthEx == 0 Payload: Null Preamble- Only Preamble: PreambleLengthEx > 0 frames Payload: Null

10 Preamble Only Access Probe Transmit Power P t 0 P0 Enhanced Preamble/Pilot Channel (I Phase or Q Phase) Configurable or Fixed Time t In a new access probe, no data will be carried. The pilot channel is transmitted either on the I phase or Q phase. The length of preamble is defined by an extended AccessParameters message. 4 slots, if PreambleLengthEx == 0 PreambleLengthEx frames, if PreambleLengthEx > 0 The output power of the preamble is configurable and the default value is set equal to the sum of data and pilot transmitted at 9.6 kbps as the current EV-DO standard states.

11 Extended Access Probe The first PreambleLengthEx frame of pilot (I-channel or Q-channel) functions as a preamble. After PreambleLengthEx frames, the probe data is enabled for up to CapsuleLengthMax.

12 AccessOffsetEx Encoding Existing AccessOffset is a 2-bit field. The AN shall set this field to indicate the slot relative to the start of the AccessCycleDuration when the AT may start an access probe according to the AccessOffset encoding table. The possible access probe offset values include 0 slot, 4 slots, 8 slots or 12 slots. The extended access probe offset is indicated by the 3-bit AccessOffsetEx field. The possible access probe offset values include 16 slots, 32 slots, 48 slots, 64 slots, 80 slots, 96 slots, 112 slots, 128 slots.

13 ProbeTimeOutAdjustEx Encoding 000' 001' 010' 011' 100' 101' 110' 111' 0 slot 16 slots 32 slots 48 slots 64 slots 80 slots 96 slots 112 slots ProbeTimeOutAdjustEx If ExtendedAccessParametersIncluded field is not included in this message, or if ExtendedAccessParametersIncluded is included and is equal to 0, then the access network shall omit this field. Otherwise, the access network shall set this field in slots according to the table.

14 PilotStrengthNominal Encoding If the ExtendedAccessParametersIncluded field is not included in this message, or If ExtendedAccessParametersIncluded is included and is equal to 0, then the access network shall omit this field. Otherwise, the access network shall set this field according to the table.

15 PilotStrengthCorrectionMin Encoding 000' 001' 010' 011' 100' 101' 110' 111' 0 db -1 db -2 db -3 db -4 db -5 db Reserved Reserved If the EextendedAccessParametersIncluded field is not included in this message, or If ExtendedAccessParametersIncluded is included and is equal to 0, then the access network shall omit this field. Otherwise, the access network shall set this field according to the table.

16 PilotStrengthCorrectionMax Encoding 000' 001' 010' 011' 100' 101' 110' 111' 0 db 1 db 2 db 3 db 4 db 5 db Reserved Reserved If the EextendedAccessParametersIncluded field is not included in this message, or if ExtendedAccessParametersIncluded is included and is equal to 0, then the access network shall omit this field. Otherwise, the access network shall set this field according to the table.

17 Conclusion Currently, mobile assisted positioning technologies on forward link have been implemented for cdma2000. EFLT, AFLT: 1X only A-GPS Reverse link LCS approach provides less mobile complexity EV-DO compatibility higher signal processing capability provided by the network almost no impact on air interface. Several enhancements to the EV-DO reverse link access probe are proposed for enhanced support of LBS in cdma2000 network. Preamble only access probe Extended access probe with data payload Extended access probe offset

18 References Shu Wang, Jungwon Min, et. al., Location Based Services for Mobiles: Technologies and Standards, Tutorial# 25, IEEE International Conference on Communication (ICC), May 2008, Beijing, China. Shu Wang, Jungwon Min, Enhanced Location Based Support in cdma2000, 3GPP2 TSG-C NTAH, Osaka, Japan, May Jialin Zou, David Rossetti and Subramanian Vasudevan, HRPD Enhancements for Improved Support of Location Based Services, 3GPP2 TSG-C WG2, Montréal, Canada, April, GPP2 X.S v2.0 (TIA-881-1): MAP Location Services Enhancements 3GPP2 X.S0024: IP Based Location Services