TSG-C Title: CSNA-Lite L2 Ack issue ____________________________________________________________________________________________________________________ Source: Rajeev Ranjan _____________________________________________________________________________________________________________________ Abstract: This contribution Discuss CSNA-Lite L2 Ack issue ____________________________________________________________________________________________________________________ Recommendation: Discuss and The source companies of this contribution grant 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. The source companies of this contribution 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 the source companies of this contribution 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 the source companies of this contribution. The source companies of this contribution specifically reserves the right to amend or modify the material contained herein and to any intellectual property of the source companies of this contribution other than provided in the copyright statement above.
2 Background CSNA-Lite protocol architecture “C R1 Updated Tunneling Protocol for 1x CSFB for approval.pdf” was approved in concept during Jun-09 New-Port Beach meeting –CSNA-Lite tunneling protocol (between UE and IWS) supports: Message header (Header version, Optional L2 acknowledgement, 1x Protocol Revision, and Logical Channel Indication) –1XLAC Protocol (between UE and IWS) also supports: Optional L2 acknowledgement 1xLAC PDU CSNA-Lite Lower Layer S102-A21 Lower Layer S102-A21 Lower Layer (Other Access Technology) 1xLAC PDU CSNA-Lite Lower Layer (Other Access Technology) UE MME IWS
3 Issues There is no need to use LAC L2 Ack and CSNA-Lite L2 Ack simultaneously. Optionality of L2-Ack in both protocols necessitates that one of them should be turned off. This requires additional configuration between UE and IWS and leads to complex negotiations. LAC L2-Ack is already in use for most 1X networks, turning it off over CSNA-Lite and turning it on again over 1x Network during CSFB will lead to extra complexity. If few Networks choose LAC L2 Ack and other networks choose CSNA-Lite L2-Ack then this would cause interoperability issues during roaming or will lead to additional complex negotiations. Few companies feel that 400ms timeout for LAC L2 Ack may not be sufficient and there may be a need of CSNA-Lite L2 Ack, but this assumption may not be true because LTE air–interface is much faster than 1X air interface and Motorola experience has shown that 400ms time out will still hold good over CSNA-Lite tunnel. –Motorola’s estimate of LTE Service Request (an analogous LTE procedure) indicates this procedure will complete well under 400 ms so Motorola believes LAC L2 Ack timer value is more than adequate
4 Recommendations –To avoid unnecessary complexity CSNA-Lite L2 Acknowledgement should permanently be turned off for 1XCSFB solution.