1. 3GPP2 C22-20120112-004r0 TSG-C SWG2.2 Title: Congestion Study of HRPD/eHRPD Networks Source: Alcatel-Lucent – Mike Dolan Abstract: This contribution provides a study of congestion in HRPD-based networks. (This version is preliminary and concentrates only on the radio interface aspects.) Recommendation: For discussion. © 2012 Alcatel-Lucent Alcatel-Lucent 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. Alcatel-Lucent 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 Alcatel-Lucent 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 Alcatel- Lucent. Alcatel-Lucent specifically reserves the right to amend or modify the material contained herein and to any intellectual property of Alcatel-Lucent other than provided in the copyright statement above.

2. 2 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. 1.Congestion Points in HRPD/eHRPD 2.(1) Congestion on the radio interface 3.(2) (3) Congestion in the AN/eAN and PCF/ePCF 4.(4) Congestion in the PDSN/HSGW 5.(5A) Congestion in the PGW 6.(5B) Congestion in the HA/LMA 7.(6) Congestion in the HSS/AAA Outline

3. ATANPCF PDSN/ HSGW HA/ LMA PGW HSS/ AAA 1 2 3 4 5A 6 5B Congestion Points in an HRPD/eHRPD network.

4. 4 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Congestion at the radio interface occurs when there are demands for greater capacity than is available. Signaling and bearer congestion are studied separately. Signaling Congestion occurs when: ­The amount of uplink signaling demand is greater than capacity. ­The amount of downlink signaling demand is greater than capacity. ­Processing capacity in the AN is exceeded, regardless of airlink capacity. Bearer Congestion occurs when: ­The amount of uplink bearer demand is greater than capacity. ­The amount of downlink bearer demand is greater than capacity. ­Processing capacity in the AN is exceeded, regardless of airlink capacity. (1) Congestion on the radio interface

5. 5 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. The amount of uplink signaling demand is greater than capacity. ­Caused by: ­Many devices attempting access at the same time. ­Insufficient configured access channel capacity. ­Bad radio conditions, causing excessive retries. ­Cell edge devices transmitting at lower rates. ­Strategies: ­Throttle the signaling from the ATs to avoid some access attempts. ­Delay some access attempts from ATs. ­Respond to some access attempts that arrive at the AN with a back-off timer. Typically these would be lower priority, higher delay tolerance, etc. ­Queue some access attempts at the AN. Typically these would be higher priority, lower delay tolerance. (1) Signaling Congestion on the radio interface Uplink Signaling

6. 6 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. The amount of uplink signaling demand is greater than capacity. ­Possible solutions: ­Use of A-Persistence, access terminal classes. ­Configuring more access channel capacity. ­Back-off retry schemes; Access queuing; Back-off timers; … ­Modifying RF attributes, when possible, to reduce retries. ­Broadcasting parameters that allow devices to decide to delay signaling: ­Priority thresholds, access class permissions, … (1) Signaling Congestion on the radio interface Uplink Signaling

7. 7 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. The amount of downlink signaling demand is greater than capacity. ­Caused by: ­Attempts to handle many devices at the same time. ­Insufficient configured control channel capacity. ­Large amounts of Data-over-Signaling (DoS). ­Cell edge devices receiving at lower rates. ­Strategies: ­Limit the access of ATs through the uplink. ­Simplify and reduce the downlink signaling. ­Configure more control channel capacity. ­Convert DoS to traffic channel messaging. (1) Signaling Congestion on the radio interface Downlink Signaling

8. 8 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. The amount of downlink signaling demand is greater than capacity. ­Possible solutions: ­See the earlier slide on solutions for uplink congestion. ­Find ways to minimize/combine downlink signaling. Much work already exists in this area. ­Configuring more control channel capacity is an operator tradeoff issue. ­Convert DoS to traffic channel messaging. This is activity that would occur in the AN, and is implementation dependent. DoS has its uses, with tradeoffs. (1) Signaling Congestion on the radio interface Downlink Signaling

9. 9 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Capacity in the AN is exceeded, regardless of airlink capacity. ­Caused by: ­Excessive uplink signaling. ­Excessive downlink signaling. ­Excessive communications to PDSNs/HSGWs. ­Insufficient processing capacity for the offered load. ­Possible solutions: ­Use uplink signaling mitigation solutions to reduce uplink processing loads. ­Discard downlink DoS traffic. ­For problems communicating with PDSNs/HSGWs: ­Offline review of A11/A10 transport capacities. ­Offline review of A11/A10 error rates. ­Increase processing/memory capacity in the AN. (2) (3) Congestion in the AN/eAN and PCF/ePCF

10. 10 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. (4) Congestion in the PDSN/HSGW

11. 11 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. (5A) Congestion in the PGW

12. 12 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. (5B) Congestion in the HA/LMA

13. 13 COPYRIGHT © 2012 ALCATEL-LUCENT. ALL RIGHTS RESERVED. (6) Congestion in the HSS/AAA