..::difficulty in CDMA::..

Yah first word after a lot of problem in our network..major issued in [W]CDMA network is: limited capacity by power, Walsh code, Traffic Channel Element, Overshooting sector that will make quality decreasing and etc
may be i will break down case by case and give a recommend what we can do to solve [in my experiences]

• Capacity limited by Power

In [W]CDMA system power is main issued of capacity, a lot of user access the network will make Ec/Io increasing, like show in a picture

too many user access the sources will make power closed to threshold. what we can make to increase capacity that caused by power limited. first of all we can increase transmit power [carrier power/cell power] that will make another space to user for access the traffic channel, increasing transmit power must balanced with limited the coverage too, cause it higher transmit power will make another neighbor cell will polluted, or we can decrease DGU [Data Gain Unit] or usually we said pilot, sync and paging, to make more spare for user. usually this case happen in urban city, cause a lot of user access Data and Voices in one time. another case is capacity limited by TCHe and Walsh Code, below is my recommend for increasing capacity will put in another point

• Capacity Limited by Walsh Code

below is a simple picture of Walsh Code Tree
in [W]CDMA system Walsh code tree 0 [W0] is used by Pilot to send user a parameter that used in [W]CDMA system like NL [Neigbor List], and etc, Walsh Code tree 1 [W1] is used for paging slot, LAC, P_REV, MIN_P_REV, T_ADD, T_DROP, T_COMP, T_TDROP is send from this slot, and Walsh Code 31 [W31] is used for sync slot.
Walsh code tree in CDMA usually use Walsh Code 64 [Vendor and Customer Agreement and specification] increase Walshcode tree will increasing Traffic Channel Element [TCHe] too, cause there are will increase and make spare for user used the sources of CDMA network.

so now we have increase more transmit power [carrier/cell power] and if still have a problem with limited capacity, we check a walsh code occupancy, if walsh code limited too, so we increase the length of walsh code. if still have a problem with a capacity again, please check how much percentage of Soft Handoff [SHO] in that site, if SHA larger than 40%, we must decrease SHO, how to decrease SHO in our network? i will write again tomorrow in another topic.

Is there a static handoff at CDMA network

once again i get a statement there is in (w)cdma network have a static handoff like i quote from my email below
Decrease T_ADD and T_Drop can adjustable if Our System Right Now Using Static Handoff (you can see parameter below)...
and
That Parameter above is Dynamic Handoff, so what ever we adjustable T_Add and T_drop for minimize SHO rate, this is no impact because system will automatically measurement EcIo from MS Side, it means the never consider value set for T_Add and T_drop
my first question is, is there static handoff in (W)CDMA network??can i get the literature?and after get that email i use www.google.com to find is there static handoff in (w)cdma network? and i cannot get the theory or any literature? or "he" can give a clearly explanation for his statement??
i think a dynamic hand off is a methode for mobile sense for handoff, in a dynamic hand off there are have a threshold function, there are different definition for dynamic handoff threshold

• in UMTS, quality function is defined as the best pilot strength
• in CDMA 2000, quality function is defined as agregate pilot strength
  

quality function is controled by t_add, t_drop, and t_comp function to measure the mobile sense for network quality, so t_add, t_drop and t_comp is used for quality control for dynamic (w)cdma handoff.

CDMA Drive Test Analysis

on monday, july 16, 2007, i go to semarang at 06.00 in the morning, we arrive in semarang at 07.00 in Ahmad Yani airport, me and mas oka handiman usually we said oka, will do ULO with dirjen Postel in solo and jogja, before we go to jogja and solo we stay 1 night in semarang, go to office and take a result of drive test for solo and jogja, this is the analyze...

a lot of HO [handover] failure

hand over fail in actual condition, cause failed when 4 handHandoff to softerr HO [3 hand], this failed cause the equipment cannot handled the MS [mobile station] to handoff 3 hand or usually we said softer hand over, to optimize this error we must invited the expert in telecommunication equipment to solve this problem , the other reason when HO failed cause lack of coverage in the area, that make MS cannot move to other PN cause there are no dominant PN or donor. to optimize this problem that we must put additional site to cover the area

feeder swap
feeder swap is installation fail, cause to achieve the OnAir target or etc, usually feeder swap in sector 1 to sector 2 or sector 0 to sector 3, as plan sector must 1 handled the call but in actual sector 2 handled the MS. this is feeder swap factor. solution foer feeder swap is we must swap back again the feeder to the normal position, do not need expert engineer, just need field engineer to swap the feeder.

cannot call
there are a lot of reason for this fail, lack of FER [Frame Erasure Rate], Ec/Io to high, or a lot of pilot polution, this three reason is main reason if MS cannot do a call, HO failure from 4 hand to 3 hand or softer HO cannot make drop call or call pre release. cause the MS still handled by another hand to do a call..

Site overshooting
Site oversoot is cause 1 sector shoot to another sector in high power, this overshoot make there are no dominant PN in MS, cause there are a lot of PN with high power in MS.
the solution for this oovershoot sector is tilting the sector, reduce power in the sector is the ast solution, for this failed.