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Selasa, 07 Juni 2011

Apa Saja Tentang Radio 3G

Tambahan lagi iseng" untuk update belajar 3G Radio nih dari forum telekomunikasi Telecomfunda ,keren juga forum itu untuk menambah wawasan engineer :)

What is Pilot Pollution?
= Simply speaking, when the number of strong cells exceeds the active set size, there is “pilot pollution” in the area. Typically the active set size is 3, so if there are more than 3 strong cells then there is pilot pollution.
Definition of “strong cell”: pilots within the handover window size from the strongest cell. Typical handover window size is between 4 to 6dB. For example, if there are more than 2 cells (besides the strongest cell) within 4dB of the strongest cell then there is pilot pollution.
= For every new user added to the service, additional noise is added to the network. That is, each new user causes a “noise rise”. In theory, the “noise rise” is defined as the ratio of total received wideband power to the noise power. Higher “noise rise” value implies more users are allowed on the network, and each user has to transmit higher power to overcome the higher noise level. This means smaller path loss can be tolerated and the cell radius is reduced. To summarize, a higher noise rise means higher capacity and smaller footprint, a lower noise rise means smaller capacity and bigger footprint.
= Active Set consists of group of cells that takes part in soft/softer handover & measure by UE.
Typical size of Active set is 3 or 4 & generally a standard practice in all WCDMA networks.
A small active set size may provide more resources available due to less soft/softer handover but at the expense of handover gain thereby reducing the capacity & link redundancy
= During Power Control, Transmit Power control(TPC) commands are used to power up or power down based on SIR target in the step of 0.5 dB ( 1 dB if the connection is made over Iur).
= Periodic LA and RA updating is used to notify the network of the UEs availability, and to avoid unnecessary paging attempts for a UE that has lost coverage and is not able to inform the CN that it is inactive. The periodic LA update procedure is controlled by a timer, called t3212, which gives the time interval between two consecutive periodic location updates. The value is sent by the WCDMA RAN to UEs on the BCCH.
=
Pilot channel power is always less than the total cell power, the ratio of the Pilot power (Ec) to the total cell power (Io) is always less than one. Thus, when measured in decibels,the value of Ec/Io is always negative.
Here is the calculation.

Ec = Effect energy
Io = Total energy and noise.
Ec/Io = 10.log[Effect energy / (total energy+noise)] < 10.log(1) = 0
Ec/Io always negative
 
What is a CE (Channel Element) in WCDMA?
 "A band Channel Element is the resource base required in the Node-B to Provide for one voice channel capacity, including the control plane to Provide for one voice channel capacity, including the control plane signaling, compressed mode, the transmit diversity and softer handover. "signaling, compressed mode, the transmit diversity and softer handover."

Factors affecting capacity in WCDMA UL and DL, sorted by descending level of importance as follows: Factors affecting Capacity in WCDMA UL and DL, sorted by descending level of Importance as Follows:
- UL: No. CE support on each Node B, interference, Node B sensivity, .. - UL: No. CE support on the each Node B, interference, Node B sensivity, ..
- DL: No. CE support on each Node B Iub interface capacity, power DL, OVSF, ... - DL: No. CE support on the each Node B Iub interface capacity, power DL, OVSF, ...

Thus, CE can be viewed as a license for each NodeB capacity (not more). Thus, CE can be viewed as a license for each vertex NodeB capacity (not more).
Each service will need some different CE UL and DL, such as: the each service will need some Different CE UL and DL, such as:
AMR 12.2 k: Uplink 1; downlink AMR 12.2 k 1: Uplink 1; downlink 1
CS / PS 64 K: 3 Uplink, downlink 2 CS / PS 64 K: 3 Uplink, downlink 2
PS 128/144k: Uplink 5; downlink 128/144k PS 4: Uplink 5; DL 4
384 k PS: Uplink 10, downlink 8384 k PS: Uplink 10; downlink 8

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