Security Level: Lampsite RTWP issue handling process www.huawei.com HUAWEI TECHNOLOGIES CO., LTD. RTWP Issue Clarification HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 2 Questions How does RTWP affect uplink performance? Why is Lampsite RTWP higher than RRU+DAS? Why is uplink performance of Lampsite better than RRU+DAS? Cell RTWP of J-building HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 3 How does RTWP affect uplink performance? RTWP is one of the factors affecting the uplink performance. When other characteristics settings are the same, HSUPA depends on the uplink scheduling, which is based on the user’s signal-to-noise ratio. Therefore, Ec / No determines HSUPA. In order to simplify the calculation, considering single user, Ec/No is : RTWP is a measured value in traffic, BGN is the background noise (non-load RTWP), ROT is raise over thermal noise The formula describes that when other conditions are the same in 2 different system, HSUPA will be the same as long as the UE transmit power achieved ROT requirement (in the power control range) . ROT shows the uplink load status directly. It reflects that how RTWP affects uplink performance. HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 4 Why is Lampsite RTWP higher than RRU+DAS(1) Higher Noise figure and RF combining Noise figure of pRRU is higher than RRU. Background noise(non-load RTWP) of pRRU is about -102dBm，while RRU is about -106dBm. Multiple RUs using uplink RF Combining will result background noise raising: Cell RTWP equals to the SectorEquipment Group RTWP which have the most pRRUs . Each cell supports a maximum 6 distributed RRU groups, groups are independent demodulation in uplink, that doesn’t add background noise. Multiple pRRUs in the same SectorEquipment Group use uplink RF Combiner, that brings background noise raising as a formula 10 * lg(pRRU number)dB. A cell can contain a maximum of 96 pRRUs. In case of 96 pRRUs in one cell, background noise will raise 10*lg(16)=12dB. Number of pRRU 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Cell background noise raising 0 3 5 6 7 8 8 9 10 10 10 11 11 11 12 12 RTWP of Lampsite with 16 pRRUs RF combined is 12dB higher than RRU+DAS system. HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 5 Why is Lampsite RTWP higher than RRU+DAS(2) Different Measurement Position of Lampsite and RRU+DAS Due to the networking structural difference between Lampsite system and RRU+DAS system, background noise (RTWP) measurement positions are different. RTWP cannot be directly used to compare the performance impact for uplink. RTWP measurement position of RRU+DAS: The RTWP measurement position of RRU+DAS system is in RRU receiver, as point 1; RTWP measurement position of Lampsite: The RTWP measurement position of Lampsite system is in pRRU receiver, same with the antenna, as point 2. Loss_DL_DAS=Loss_UL Antenna coverage radius Point 1 d(m) -85dBm P_DL_RRU=33dBm P_ANT RRU+DAS UE BBU RRU Noise Figure :NFRRU=1.6dB RRU Point 2 RRU background noise:(-106 ) dBm Equivalent background noise of antenna -85dBm P_DL_pRRU Lampsite BBU RHub pRRU Noise Figure:NFpRRU=12dB UE RHub pRRU No equivalent RRU original background noise Background noise of single pRRU:(-102) dBm HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 6 Why is uplink performance of Lampsite better than RRU+DAS? To obtain the same ROT, lower UE transmit power is needed Analyze the difference of uplink performance in Lampsite(single pRRU) and single RRU+DAS: RTWP contains 2 parts: useful signal and noise, that is RTWP = PN (dBm) + ROT (dB) = PN (dBm) + Ec (dBm) = 10*lg(10^(PN/10) +10^(Ec/10)), so Ec= PN + 10*lg (10^(ROT/10)-1). PN is the background noise, Ec is useful signal. Ec = UE transmit power – path loss Considering UE receives same RSCP( such as -85 dBm ) both in Lampsite and RRU+DAS. Therefore, UE transmit power = Ec + path loss= PN + 10*lg(10^(ROT/10)-1) + path loss RRU+DAS: UE transmit power = PN + 10*lg(10^(ROT/10)-1) + [ 33 - ( -85 ) ] = 12 + 10*lg(10^(ROT/10)-1) Lampsite: UE transmit power = PN + 10*lg(10^(ROT/10)-1) + [ 10 – ( -85 ) ] = -7 + 10*lg(N) + 10*lg(10^(ROT/10)-1) If there is only 1 pRRU, UE transmit power in Lampsite is 19dB lower than RRU+DAS; If there are 16 pRRUs RF combing, UE transmit power in Lampsite is 7dB lower than RRU+DAS. Even pRRUs are RF combined, uplink performance of Lampsite is better than RRU+DAS. HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 7 Conclusion : 1.Due to the networking structural difference between Lampsite and RRU+DAS system, background noise (RTWP) measurement positions are different. 2. Reported RTWP values of Lampsite is higher than RRU+DAS. 1. The more pRRU in one SectorEquipment Group, the less advantage for Lampsite to RRU+DAS in uplink performance. 2.Even in case of 16 pRRUs in one sector equipment group, uplink performance of Lampsite is better than that of RRU+DAS. HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 8 Cell RTWP of J-building The monitored RTWP in J-building is as the follow figure: That basically matches the counter --------RTWP= -102 + 10 * lg(pRRU number) : Cell ID 1 2 3 4 5 6 Maximum number pRRU of 7 3 2 6 6 3 sectorequipment Group Cell background noise raising 8 5 3 8 8 5 Calculated value -94dB -97dB -99dB -94dB -94dB -97dB Monitored value -93dB -97dB -99dB -94dB -94dB -97dB RPWT of cells in J-building is normal. HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 9 TX Power of J-building (from benchmark test) The TX Power of J-building is as the follow figure: The DBS+DAS average TX Power is -34.7dBm, and Lampsite is -42.3dBm. Although Lampsite RSCP is 12dBm lower than DBS+DAS, TX Power in Lampsite is still lower than DBS+DAS. TX Power in Lampsite is lower than legacy. HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 10 Desensitization Clarification HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 11 Power mismatch causes Lampsite RTWP raise Macro Downlink Lampsite Lampsite Macro balance point RTWP coverage issue issue Uplink balance 1A event 1D event point UE moves forward to the Lampsite HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 12 Desensitization kills the power mismatch Lampsite Macro RWP issue coverage issue Macro Uplink Downlink Lampsite balance point balance point After desensitization Macro Lampiste Uplink & Downlink point HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 13 P_PCPICH_ LampSite -TL_Lampsite_Downlink = P_PCPICH_macro - TL_Macro_Downlink P_UE - TL_Lampsite_Uplink - NF_Lampsite - G_ULDiv_ LampSite = P_UE - TL_Macro_Uplink - NF_Macro - G_ULDiv_Macro + Des_Lampsite Des_Lampsite =(P_PCPICH__macro-P_PCPICH_ LampSite)+ (NF_Macro- NF_LampSite)-(G_ULDiv_Macro-G_ULDiv_ LampSite) P_PCPICH_ Macro=33dBm G_ULDiv_Macro=G_ULDiv_ LampSite=3dB Deslampsite=(33-P_PCPICH_ LampSite)+ [(-106)-(RTWP_LampSite_NoLoad)] HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 14 RTWP Issue Handling Process HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 15 1, Query the 0% Load cell RTWP 2, Calculate the desensitization intensity based on the formular of Intensity_DESENS=(33-P_PCPICH_ LampSite)+ [(-106)-(RTWP_LampSite_NoLoad)] 3, Run MML to set the desensitization SET ULOCELLDESENS: ULOCELLID=1111, DI=X; 4, Query the 0% Load cell RTWP again to check whether the Desensitization take effect 5, Based on the newly updated RTWP, calculate the value of the real background noise parameter Background Noise = 1121+RTWP_LampSite_NoLoad *10 6, Deactivate the cell on RNC DEA UCELL: CellID=XXXX 7. Run MML to modify the Background noise on RNC MOD UCELLCAC：CELLID=XXXX， BackgroundNoise=XX； 8. Activate the cell again ACT UCELL: CELLID=XXXX HUAWEI TECHNOLOGIES HISILICON CO., LTD. SEMICONDUCTOR Page 16