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Hi all,
1–How does BTS/BSC comes to know about the speed of a MS.
2–How do we make it possible that fast moving MS essentially camps only on certain fixed cells in UL/OL types.
Regards
1. in dedicated mode,
in underlaid : the speed of MS can be computed by how long the MS receives the signal from a overlaid cell above a certain threshold. MS is detected as SLOW
in overlaid :the speed of MS is computed based on how long the MS stays in an overlaid cell between 2 handovers. If this duration is too short, it means the MS is going fast and will be sent to underlaid cell. MS is detected as FAST.in idle mode, there is no mechanism : type of the cell is not known by the MS
2. in idle mode (you said “to camp”, which refers to idle mode), you can use the cell reselect offset :
UL cell CRO = 0dB
OL cell CRO = 4 to 10dB
you can use temporary offset and penalty time to allow only slow moving MS to reselect un OL cell
(in OL cells only : temp offset = 40s, penalty time = 30dB)regards,
pixHi MKT,
1–In Ericsson we have two parameters for this purpose. THO and NHO. If the number of inter-cell handovers during the last THO seconds exceeds NHO in a cell, the mobile is considered to be “fast” in the cell.
2– In Ericsson HCS feature takes care of it if those certain cells are assigned to a higher(bigger) layer.
Dear MKT,
Speed based preference is allowed in most of the vendors,especially to cater for hierarchical networks. Micro, Mini and Macros.
The objective is to keep the Faster moving MS on Macros, Slower on Minis and Slowest / indefinite MS on Micros. There by balancing Traffic load and optimizing HO per Call, thereby reducing need for excess HOs and resulting in lower chances of Ho Failires and Call Drops.
HOs can be as follows.
Capturing HOs from Macro to Micros (Slow Moving MS)
Emergancy HOs from Micros to low traffic Macros (Fast Moving MS).For Alcatel: The calculations are based on Min_Dwel_Time and Min_Connect_Time to classify MS as slow / fast. then If Speed_discripancy is enabled the then HOs take place.
For the Idle mode the Penalty time and Temporary offset are used to allow only slow moving MS to camp on to a specific cell. The Penalty time should be optimized based on the traffic type of the cell. Lets say its on a traffic signal then the Penalty time should be greater than the Signal change time thereby the Moving MS in cars dont camp onto the micro.
Radio link management in hierarchical networks
Cell Layers and Dwell Time
Mobile speed is estimated from the variation of the field strength received by the mobile from the target cell. Considering the case of a network composed with three layers. The method of
estimation is based on the computation of two averages of the field strength received by the mobile from the target cell.– A “fast” mobile connected to a cell of the lowerlayer must
handover towards a cell of the middlelayer. Nevertheless the field strength received from the cell of the middlelayer must be high enough to trigger the handover.– A “slow” mobile connected to the lowerlayer must handover
towards a cell of the same layer.
In both cases the estimation of mobile speeds are based on the
field strength received from a cell of the lowerlayer.– A “fast” mobile connected to a cell of the upperlayer must
handover towards a cell of the same layer.– A “slow” mobile connected to a cell of the upperlayer must
handover to a cell of the middlelayer.
In both cases the estimation of mobile speeds are based on the
field strength received from a cell of the middlelayer.– A “fast” mobile connected to a cell of the middlelayer must
handover towards a cell of the upperlayer. Nevertheless the field
strength received from the cell of the upperlayer must be high
enough to trigger the handover.
The estimation of mobile speeds is based on the field strength
received from a cell of the middlelayer.– A “slow” mobile connected to a cell of the middlelayer must
handover towards a cell of the lowerlayer. The estimation of
mobile speeds are based on the field strength received from a cell of the lower layer.
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