RTWP and load analysis report 22-May-2013
Introduction The aim of this report is to show the status of RTWP and load in
MTN network and our recommendations to improve them.
Overview RTWP is the Uplink Received Total Wideband Power. The RTWP is indicated by the VS.MeanRTWP counter, if the value of
VS.MeanRTWP is greater than -100 dBm then the uplink load and the HSUPA uplink capacity are limited. The average HSUPA throughput is indicated by the VS.HSUPA.MeanChThroughput counter. If the average HSUPA throughput of an HSUPA user is smaller than 150 kbit/s, this user is processing low-speed data services. The following charts show the average VS.MeanRTWP and VS.HSUPA.MeanChThroughput over the period between 13 and 17May-2013.
RTWP & HSUPA.MeanChThroughput
Analysis From the chart of RTWP, we can see that the average RTWP value is
acceptable. However, the average HSUPA throughput is low.
Issues to be noted here in MTN parameters configuration are the
following: The UL Call Admission Control (CAC) function is configured with Power-based Admission Algorithm 2 which depends on the Equivalent Number of Users (ENU), and the “UL total equivalent user number” parameter is set to a high value (160) comparing to the default value (95). And the thresholds for admitting the UL users are all higher than the default value hence more UL users are being admitted by these configurations. Load Reshuffling (LDR) function’s thresholds also are configured with higher values than the default. During the connection, these configurations slow the triggering of load reshuffling actions such as Inter frequency HO, code reshuffling, and BE service rate reduction. •
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Analysis •
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IRAT HO is not configured as an option for load reshuffling except for 38 cells (HO to 2G network because of load is not allowed). Overload Control (OLC) function is not configured. The number of cells which handle more than 15 mean number of HSUPA users is about 70. The charts in the next slide show the UL power congestion appeared (due to high UL load) after changing the UL total equivalent user number to 95 (in the first chart), and after changing the UL Power-based Admission Algorithm 2 to 3 “which depends on power for admitting users not ENU” (in the second chart).
All of these issues indicate that the load in MTN 3G network is high.
Analysis
Actions & recommendations In order to reduce the RTWP mean value, increase the throughput, enhance the
user experience, and make sure the algorithms are working well, the following actions are done or recommended: Four CAC algorithm switches have been activated for 360 cells. Intra frequency LDB algorithm switch has been activated for 118 cells. PUC algorithm switch has been changed for 34 cells. Four LDR algorithm switches have been activated for 304 cells. 64QAM and DL L2ENHANCED function switches have been activated for 29 cells. DC-HSDPA function switch has been activated for 4 nodeBs. Parameters’ discrepancies have been sent to be checked. 2nd carrier is preferred to be activated for the cells with high RTWP or high load. Configuring IRAT HO is preferred to be an option for LDR especially for the 2G cells with low TCH utilization. Changing the IRAT parameter “Qoffset1sn” from 15 (which makes the probability of selecting inter-RAT neighboring cells smaller) to normal (0) is preferred. • • • • •
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Actions & recommendations •
The performance of the network will be checked after applying the previous actions. The following features could be checked also for specific cases (if any) for any further needed improvements: 1. HSUPA UL Interference Cancellation: this feature reduces uplink interference and improves uplink system capacity. It is used when the system needs to support a small number of HSUPA users that require high throughput and a large number of HSUPA users that require low throughput. 2. Dual-Threshold Scheduling with HSUPA Interference Cancellation: recommended for a cell where the following conditions are met: The feature HSUPA UL Interference Cancellation is activated. The operator wants to further increase the HSUPA capacity in the uplink. The cell's uplink load is heavy. For example, the load constantly exceeds the value for MaxTargetUlLoadFactor.
Actions & recommendations 3. HSUPA Anti-interference Scheduling: This feature is used to reduce the impact of strong interference on the network, maintaining a high HSUPA throughput and significantly improving user experience. This feature is not recommended in some scenarios and it should be studied well before applying. To apply the previous features, the prerequisites (including HW ones) should
be available.
Appendix In this study the below points were covered: The reporting period of load measurements functions , Load
Measurement Filtering, Auto-Adaptive Background Noise Update Algorithm parameters have been checked. PUC, CAC, LDB, LDR, OLC, and DCCC algorithms and parameters
have been checked both in UL and DL. PUC, LDB, LDR, and OLC timers have been checked.
Thank You
