huawei wcdma load control

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Huawei WCDMA Load Control

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  • 1www.huawei.com

    Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    WCDMA Load Control

    The WCDMA system is a self interference system. As the load of the WCDMA system increases, the interference rises. A relatively high interference may affect the coverage and Quality of Service (QoS) of established services. Therefore, capacity, coverage and QoS of the WCDMA system are mutually affected. The purpose of load control is to maximize the system capacity while ensuring coverage and QoS.

  • 2Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Objectives Upon completion of this course, you will be able to:

    Know the load control principles

    Know the load control realization methods in WCDMA system

    Know The load control parameters in WCDMA system

  • 3Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Contents1. Load Control Overview

    2. Basic Load Control Algorithms

  • 4Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Contents1. Load Control Overview

    2. Basic Load Control Algorithms

  • 5Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Load Definition Load: the occupancy of capacity

    Two kinds of capacity in CDMA system

    Hard capacity

    Code channels

    Hard ware resource: Transport resource, NodeB processing capability (CE)

    Soft capacity Interference (UL) Power (DL)

  • 6Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Uplink Load Definition Cell Load Factor:

    risenoiseUL11=

    NPRTWP

    risenoise =

    PN: Background noiseIn the uplink, the RTWP value can be measured easily. Therefore, the UL cell load factor (based on RTWP) can be used to describe UL load.

  • 7Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Downlink Load Definition

    R99 load controlTransmitted carrier power of all codes not used for HS-PDSCH or HS-SCCH transmission

    DL Load R99 and HSDPA load control

    Total Carrier Power (TCP)

    HSDPA load controlHS-DSCH Required Power

    HSDPA load controlHS-DSCH Provided Bit Rate

    R99 load controlCell Load Factor (based on RTWP) RTWP (Received Total Wideband Power)

    UL Load

    ScenarioCommon Measurement in Node B

    The definition of DL load is very different from the definition of UL load, the adjacent cell interference factor and the non-orthogonality factor in the downlink are very difficult to measure and calculate, therefore, the DL cell load factor can not be used to describe the DL cell load. Then, the transmission power is used to describe DL load.

  • 8Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    The Objectives of Load Control Keeping system stable

    Maximizing system capacity while ensuring the coverage and QoS

    PUC: Potential User ControlCAC: Call Admission Control IAC: Intelligent Admission ControlLDR: Load Reshuffling OLC: Overload Control

    3. After UE access2. During UE access1. Before UE access

    Time

    LDRCACPUC OLC

    IAC

    Load control algorithm can be classified into three parts according to the different working states of UE.Before UE accesses, the PUC algorithms will function. RNC will monitor the cell load periodically. If the current cell load exceeds a specific threshold, RNC will modify the cell selection and re-selection parameters, in order that UE can select the low-load cell easily when UE will initiate some services and work at CELL-DCH state. This algorithm aims at UE which working at IDLE mode, CELL-FACH state, CELL-PCH state or URA-PCH state in this cell. During UE accesses, the CAC and IAC algorithms will function. RNC will judge whether the new access is admissible. After UE accesses, LDR and OLC algorithms will function. There are some practical algorithms to decrease the cell load. When a cell is in basic congestion, the RNC shall select some UEs for inter-frequency handover. When a cell is in overload congestion, the RNC shall select some UEs to release if failing to release the cell from overload congestion by BE service TF control.

  • 9Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Load Control Algorithms

    No Load control

    PUC starts: to enable UEs in idle mode to camp on cells with light loadLDR starts: to check and release initial congestion in cells

    CAC or IAC: to prevent new calls into cells with heavy loadDRD starts: to enable rejected UEs to retry neighboring cells or GSM cells

    NodeB transmitpower (noise)

    Cell load

    OLC starts: to reduce the TFs of BE subscribers, and release some UEs forcibly

    Icons for different load levels

    In a cell, the higher the cell load, the higher the NodeB transmit power (noise). In this diagram, different icons indicates different load levels. And for different load levels, the different load control algorithm will function.

  • 10

    Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Load Measurement The objectives of LDM (LoaD Measurement)

    Measure the system load

    Filter the measured data according to the requirement of different load control algorithms

    Major Measurement Quantities Uplink Received Total Wideband Power (RTWP) Downlink Transmitted Carrier Power (TCP) TCP of all codes not used for HSDPA transmission Power Requirement for Guaranteed Bit Rate (GBR) on HS-DSCH Provided Bit Rate (PBR) on HS-DSCH

    For LDR and OLC algorithms, the LDM algorithm needs to decide whether the system works in basic congestion or overload congestion mode and to notify related algorithms for handling.Delay susceptibilities of PUC, CAC, LDR, and OLC to common measurement are different. When some or all the algorithms use the same common measurement, the LDM must apply different smoothed filter coefficients in order to get rippling and timely common measurement as required.

  • 11

    Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    LDM procedure

    Smooth Window Filtering on the RNC Side N : the size of the smooth window

    : the reported measurement value

    1

    0( )

    N

    n ii

    PP n

    N

    =

    =

    nP

  • 12

    Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Parameters for LDM (1) CHOICERPRTUNITFORULBASICMEAS

    /CHOICERPRTUNITFORDLBASICMEAS (Time unit for UL/DL basic meas rprt cycle) Value Range: TEN_MSEC, MIN

    Recommended value: TEN_MSEC, means the time unit is 10ms

    Set the following parameters through SET LDM, query it through LST LDM.

  • 13

    Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Parameters for LDM (2) TENMSECFORULBASICMEAS/TENMSECFORDLBASICMEA

    S (UL/DL basic meas rprt cycle, Unit:10ms) Value Range: 1~6000

    Recommended value: 20, namely 200ms

    MINFORULBASICMEAS/MINFORDLBASICMEAS (UL/DL basic meas rprt cycle, Unit: min) Value Range: 1~60

    Recommended value: none

    Notes:1. [LDR period timer length] and [OLC period timer length] which are configured in the command SET LDCPERIOD must be twice greater than the UL basic common measurement report cycle.2. [Intra-frequency LDB period timer length], [PUC period timer length], [LDR period timer length] and [OLC period timer length] which are configured in the command SET LDCPERIOD must be twice greater than the DL basic common measurement report cycle.

  • 14

    Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Parameters for LDM (3) ULBASICCOMMMEASFILTERCOEFF /

    DLBASICCOMMMEASFILTERCOEFF (UL/DL basic common measure filter coeff) Value Range: D0, D1, D2, D3, D4, D5, D6, D7, D8, D9, D11, D13,

    D15, D17, D19

    Recommended value: D6

    ULBASICCOMMMEASFILTERCOEFF / DLBASICCOMMMEASFILTERCOEFF (UL/DL basic common measure filter coeff)This parameter specifies the L3 filtering coefficient of the measurement value on the NodeB side. The greater this parameter is, the greater the smoothing effect and the higher the anti slow fading capability, but the lower the signal change tracing capability. The change of this parameter has an effect on PUC, CAC, LDR algorithms.

  • 15

    Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Parameters for LDM (4) The parameters for smoothing filter window

    25132DlOLCAvgFilterLenDL OLC moving average filter length25132UlOLCAvgFilterLenUL OLC moving average filter length3132DlCACAvgFilterLenDL CAC moving average filter length3132UlCACAvgFilterLenUL CAC moving average filter length

    25132DlLdrAvgFilterLenDL LDR moving average filter length25132UlLdrAvgFilterLenUL LDR moving average filter length32132PucAvgFilterLenPUC moving average filter length

    Recommend ValueValue RangeParameter IDParameter Name

    These parameters specify the length of smoothing filter window of the report measurement value on the RNC side. The greater these parameters are, the greater the smoothing effect, but the lower the signal change tracing capability.

  • 16

    Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Parameters for HSDPA LDM (1) CHOICERPRTUNITFORHSDPAPWRMEAS (Time unit of

    HSDPA need pwr meas cycle) Value Range: TEN_MSEC, MIN

    Recommended value: TEN_MSEC, means the time unit is 10ms

    CHOICERPRTUNITFORHSDPARATEMEAS (Time unit of HSDPA bit rate meas cycle) Value Range: TEN_MSEC, MIN

    Recommended value: TEN_MSEC, means the time unit is 10ms

  • 17

    Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

    Parameters for HSDPA LDM (2) TENMSECFORHSDPAPWRMEAS (HSDPA need pwr meas

    cycle,Unit:10ms)