How to Solve Interference Problem in GSM Network

How to Solve Interference Problem in GSM Network

The solution for interference problem depends on the followin followingf gfa actors1. Whether Whether interfere interfererr comes comes from internal internal or external source2. What is the cause of internal interference, whether it were caused by bad frequency planning, site location, cove co vera rage ge prob proble lem m or or imp imple leme ment ntat atio ion n pro probl blem em.. The The foll fo llow owin ing g flow fl ow char chartt shows how to overcome interference interference problem in the network

The potential interferer can be identified by displaying the cells using the same or adjacent frequency (frequencies)geographically

The other solution to reduce interference level in the network is activation radio network features. The following radio features are proposed to be activated to reduce interference level in the network1. !iscontinuous Transmission "!T#$2. %T& and '& (ower )ontrol*. +requency opping-. 'ultiband )ell can be an alternative for operator who has limited frequency bandwidth. t will reduce interference level by using common %)). /nother benefits to have multiband cell are trunking gain, simplify neighboring system and high configuration site How to Identify Interference in GSM Network ( 1)

One major challenge when optimizing GSM network is the detection of  cellssuering from interference as interference is limiting the capacity and harming the quality of the network. This prolem occurred due to limited andwidth and limitednumer of carrier frequency.There are two categories of interference source that are!" #nternal #nterference! $o"channel or %djacent channel interference causinginternal interference." &'ternal #nterference! &'ists when there is another transmitter or something elseacting as a transmitter outside the network such as T( transmission) *ailwayStation frequency) and microwa+e links.#nterference #denti,cation using *adio -etwork Statistic*adio network statistic *-S/ can e used to analyze if  speci,c cells suer frominterference and which frequency channels are in+ol+ed. % cell in GSM can suerfrom interference either in the uplink or downlink or in oth directions. %s theinterference is related to the frequency or a set of frequencies in case of frequencyhopping) it is interesting to see which T*0 suers from interference if interferencehappened in 1$$2 T*0 or 2opping T*0. The interesting parameter in this case isthe assigned frequency to the indi+idual T*0. %fter the distured cell and therelated frequencies are identi,ed) potential interferer cell can e identi,ed. 3or thispurpose a geographical analysis can e performed. 3requency retune ecomes thesolution if 1$$2 frequency suers from interference. #n case  T$2 frequencyfurther identi,cation shall e performed if hopping system is assigned to T*04s.There are se+eral indicators from *adio -etwork Statistics that can e used toidentify the interference in the network.5. The correlation etween *'6e+el to *'7ual.%n indication for interference will e that the recei+e le+el is good ut at the sametime the recei+e quality is poor. This can e analysed for oth directions uplink anddownlink/ separately. #t is etter to ha+e this ,gure for 1$$2 T*0 and hoppingT*0 so we can identify whether interference e'ists at 1$$2 T*0) #ndi+idual T*0non"hopping case/ or 2opping T*0.

indicator is a lot of reversion to old channel activity due to target frequency mightbe interfered.nother ways to identify internal interference in GSM network is by scanningfrequency at idle mode. t this case! GSM recommendation introduces referencevalue of interference level (GSM "ecommendation. #$.#$%.&he actual interference ratio is defined as the interference ratio for  which this'erformance is met. &he actual interference ratio shall be less than a s'ecified limit!called the reference interference ratio. &he reference value of interference will showcochannel interference()*Ic% and ad+acent channel interference ()*Ia%.

)*Ia calculation shows that carrier to interference level of first ad+acent (,##-Hs'acing% and second ad+acent (/## -H s'acing% e0ceeds minimum value of interference level (1 d2 for first ad+acent and /3 d2 for second ad+acent%. So! wecan conclude that there is no interference to channel $3,.4istribution )*I from drive test with dedicated mode also can be used as figure todescribe level interference on drive test route. 5e can do analysis se'aratelybetween )*I distribution on 2))H carrier and )*I on Ho''ing list carrier.60ternal interference can7t be detected using drive test tool. s instead! scanningfrequency using s'ectrum analyer is used to observe the source of  e0ternalfrequency