1. Hauwei hcs in dual band netwrok
xNetmanager Overview
Hauwei hcs in dual band netwrok
Alex yang
november 2013
Ericsson AB 2011

2. index INTRODUCTION For HCS HCS Related parameter and algorithm.
Huawei HCS strategy.
Advantage of HCS.
Possible scenario for HCS change/optimization.
HCS Related parameter and algorithm.
Active mode control.
Related parameters.

3. Huawei HCS strategy Priority: Micro>GSM 1800>GSM 900>Umbrella
Upper Layers are used for coverage. Under Layers are used for capacity.

4. Advantage of HCS
The under layers (L1 and L2) which are mainly on 1800 band have narrow propagation model and longer spectrum which can provide better voice quality and better capacity.
The upper layers (L3 and L4) which are mainly on 900 band have wide propagation model and good diffraction capability which can provide better signal strength and coverage.
In most common cases, only L2 and L3 are specified to simplify the network structure.

5. Possible scenario for HCS opt.
Traffic distribution optimization.
Blocking: Balance traffic between co-located sectors (900 and 1800) can solve the problems like blocking/congestion.
RxQual: As what mentioned before Band has less interference but worst signal strength while 900 Band has better coverage but more interference. So appropriate traffic distribution between 900 and 1800 band can improve the interference/SS related KPIs like drops, RxQual, etc.
Traffic balance before spectrum refarming.
Before caving the spectrum in one band, it is better to push the traffic to the other band to decrease the interference on the band which you want to carve.

6. Active mode control
When the measured signal strength is higher than threshold A. Layer HO is triggered from 900 band to 1800 band.
When the current signal strength is lower than threshold B. EDGE HO is triggered from 1800 band to 900/1800 band.

7. Active mode control
1800 Band Incoming HO threshold(THR A) = 1800 Cells Layer HO threshold to 1800 HO hysteresis – 64.
The layer HO threshold is the main factor for 1800 band to absorb traffic. If 1800 Band is expected to absorb more traffic, the value should be lower. 900 to 1800 HO hysteresis is adjacency parameter to control cell to cell traffic trend.
1800 Band outgoing HO threshold(THR B) = 1800 Band cells EDGE HO threshold.
The HO from 1800 band to 900 band is mainly trigger by EDGE HO. If more traffic is expected to stay on 1800 Band. The value should be lower.

8. Active mode control
<Note: It is not recommended to make the EDGE HO too low (less than 20 (-90 dBm)), since it will lead to poor coverage due to no HO.>
Principles:
Margin between THR A and THR B is necessary to avoid ping-pong HO between 900 and 1800 Bnad
The EDGE HO from 1800 to 900 can be triggered by both DL or UL. Due to UL SS is always lower than DL SS. UL EDGE HO threshold should be dB lower than DL EDGE HO threshold.
It is recommended to adjust the IDLE mode parameter (CRO etc.) to the traffic distribution needed. I.e. to give higher priority to 1800 in cell selection.

9. Active mode control Example: Right Settings
THR A
THR B (DL)
The DL SS when UL SS< UL EDGE HO threshold
Wrong settings lead to less traffic on 1800 than expected
THR A
The DL SS when UL SS< UL EDGE HO threshold
THR B (DL)
Mistake lead to Ping-Pong HO between 1800 and 900 Band
The DL SS when UL SS< UL EDGE HO threshold
THR A
THR B (DL)

10. parameters Parameter name Meaning Value range Recommended value
Edge HO UL
RX_LEV Thresh.
During the statistics time, if the time in which the uplink receiving level is lower than the value is longer than certain time called continuous time, edge handover will be performed. If PBGT handover is enabled, Corresponding edge handover threshold will be set Lower
0 ~ 63
25 (without PBGT handover, downtown), 15 (single station on outskirts), 15 (with PBGT handover, downtown)
Edge HO DL
Downlink consideration for edge HO
30 (without PBGT handover, downtown), 20 (single station on outskirts), 20 (with PBGT handover, downtown)

11. parameters Parameter name Meaning Value range Recommended value
Layer HO
Thresh.
It affects the value of the 14th bit in the 16bit ranking , and it is also the level requirement on the target cell for interference handover and load handover. Then such level should be higher than layer handover threshold + layerhandover hysteresis. The layer handover threshold should be set >= Edge handover threshold + Inter cell handover hysteresis.
0 ~ 63
(-110~-47dBm) 25
Inter cell HO
hysteresis
Handover hysteresis between an adjacent cell and the serving cell. It is set to reduce “Ping pang” HO. The hysteresis value also needs to be adjusted according to the handover performance statistics result and live network. Flexible configuration of the value can effectively lead handover and
traffic between two adjacent cells.
0 ~ 63 dB
It is around 4 in the densely populated downtown, and
around 8 on the
outskirts.