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• In order to meet the defined quality requirements (BLER) a certain average bit-energy divided by total noise+interference spectral density (Eb/N0) is needed. Nokia simulations for Eb/No are based on ITU recommendations.
• Eb is the received energy per bit from the wanted user,• Io is the total received power density, from both interference and thermal noise,
excluding the power of the wanted signal.
• Eb/No depends on:• Service• MS speed• Radio channel
Where:Prx = received powerR = bit rateW = bandwidthIown = total power received from the serving cell (excluding own signal)Ioth = total power received from other cellsPN = noise power = orthogonality factor
Interference MarginInterference margin is calculated from the UL/DL loading () values. This
parameter shows in DL how much the BTS "sensitivity" is decreased due to the network load (subscribers in the network) & in UL indicates the loss in link budget due to load
Slow and Fast Fading• Slow Fading (Log-normal Fading)
In the real enviroment the propagation condition of the electromagnetic wave are not stable. Some location and time dependant variation in a signal strength appear when the mobile moves around (shadowing effect). The variation of the signal strength are normal distibuted on the logarithmical scale.
• Soft handover gain is the gain against shadow fading. This is roughly the gain of a handover algorithm, in which the best BTS can always be chosen (based on minimal transmission power of MS) against a hard handover algorithm based on geometrical distance.
• In reality the SHO gain is a function of required coverage probability and the standard deviation of the signal for the environment.
• The gain is also dependent on whether the user is outdoors, where the likelihood of multiple servers is high, or indoors where the radio channel tends to be dominated by a much smaller number of serving cells.
• For indoors users the recommendation is to use smaller SHO gain value.
Power control headroom is the parameter to describe the margin against fast fading. This parameter is needed because at the cell edge the mobile does not have enough power to follow the fast fading dips. This is especially important for the slow moving mobiles
Power Control Headroom = (average required Ec/I0) without fast PC - (average required Ec/I0) with fast PC
Source: Radio Network Planning & Optimisation for UMTS; J. Laiho, A. Wacker, T. Novosad; Tab. 4.5
without fast PC with fast PC5Hz 13,1 4,9 8,220Hz 11,5 5,7 5,840Hz 9,7 6,0 3,7100Hz 7,9 6,0 1,9240Hz 6,5 6,3 0,2
average requierd Ec/ I o [dB]max Doppler f r. Power Control Headroom
Bit rate bit/s 64000 aTotal TX power available dBm 21 bTX antenna gain dBi 2 cBody loss dB 0 dTX EIRP per traffic channel dBm 23 e=b+c-dRX antenna gain dBi 18 fRX cable and connector losses dB 3 gReceiver noise figure dB 3 hThermal noise density dBm/Hz -174 jCell loading % 70 kNoise rise due to interference dB 5.23 l=10*log10(1/(1-(k/100)))Total effect of noise dBm/Hz -171 m=h+jInformation rate dBHz 48.06 n=db(a)Effective required Eb/No dB 2.54 oRX sensitivity dBm -115.40 p=l+m+n+o+correction factorSoft Handoff Gain dB 4.5 qFast fading Margin dB 2.5 rLog normal fade margin dB 11.6 sIn-building penetration loss (urban) dB 20 tMaximum path loss urban dB 123.80 pl=e+f+q-g-p-r-s-t
Uplink Budget
Service Bit Rate
Max. UE power
Tx antenna gain, e.g. 2dBi for a dipoleAttenuation due to body obstruction.Rx antenna
gain in the boresight directionCable and connector losses between the Rx antenna and the cabinet
Source thermal noise
Loading converted to noise riseLoading in the cell
Bit rate bit/s 64000 aTotal TX power available dBm 21 bTX antenna gain dBi 2 cBody loss dB 0 dTX EIRP per traffic channel dBm 23 e=b+c-dRX antenna gain dBi 18 fRX cable and connector losses dB 3 gReceiver noise figure dB 3 hThermal noise density dBm/Hz -174 jCell loading % 70 kNoise rise due to interference dB 5.23 l=10*log10(1/(1-(k/100)))Total effect of noise dBm/Hz -171 m=h+jInformation rate dBHz 48.06 n=db(a)Effective required Eb/No dB 2.54 oRX sensitivity dBm -115.40 p=l+m+n+o+correction factorSoft Handoff Gain dB 4.5 qFast fading Margin dB 2.5 rLog normal fade margin dB 11.6 sIn-building penetration loss (urban) dB 20 tMaximum path loss urban dB 123.80 pl=e+f+q-g-p-r-s-t
Path loss = Tx signal + all gains - losses - ( SNR + Noise)
Chip rate 3840,00 DL data rate 64,00UL Data rate 64,00 DL load 85%
UL Load 50%2
Uplink DownlinkRECEIVING END Node B UEThermal Noise Density dBm/Hz -173,98 -173,98Receiver Noise Figure dB 3,00 8,00Receiver Noise Density dBm/Hz -170,98 -165,98Noise Power [NoW] dBm -105,14 -100,14Reguired Eb/No dB 2,00 5,50Soft handover MDC gain dB 0,00 1,00Processing gain dB 17,78 17,78Interference margin (NR) dB 3,01 8,24Required Ec/Io [q] dB -15,78 -12,28Required Signal Power [S] dBm -117,91 -105,18Cable loss dB 2,00 0,00Body loss dB 0,00 0,00Antenna gain RX dBi 18,00 0,00Soft handover gain dB 2,00 2,00Power control headroom dB 3,00 0,00Istropic power dBm -132,91 -107,18
TRANSMITTING END UE Node BPower per connection dBm 21,00 24,73Cable loss dB 0,00 2,00Body loss dB 0,00 0Antenna gain TX dBi 0,00 18Peak EIRP dBm 21,00 40,73Isotropic path loss dB 153,91 147,91DL peak to average ratio dB 6,00Isotropic path loss to the cell border 153,91
Define Search Areas• The sites in a nominal plan are only imaginary.• To become a real network, physical sites are required.• A suitable physical site must be found for each nominal site.• A suitable physical site must amongst other things:
• Give adequate radio coverage.• Have connectivity into the transmission network.• Be aesthetically and politically acceptable to the local community.• Have power nearby, good access and a co-operative owner.
• A survey of each nominal site is normally carried out to identify possible site options which meet the above criteria.
Bad GSM Sites• In GSM, there were two types of bad sites.
• Donkeys - Low sites which provide very little coverage.• Donkeys carry so little traffic that they often never pay for themselves.
• Boomers - High sites which propagate much further than is needed.• A boomer will cause localised interference and prevent capacity being added to some
Site Selection Guidelines• The objective is to select a site location which covers the desired area but
keeps emissions to a minimum.• The site should be located as close to the traffic source as possible.
• The closer the site is to the traffic, the less output power will be required by the user equipment and node B. This will minimise the noise affecting other users on both the serving cell as well as other nearby cells.
• The antenna height selected will depend largely on the type of environment in which the site is to be located. Eg Dense Urban, Urban, Suburban, Rural.
• The key factor to be considered is how well can the emissions be controlled.
Using Existing Cellular Sites• Most UMTS networks will be built around an existing GSM network.• Many GSM networks were built around existing analogue sites.• In the early days of analogue cellular sites were often located to give
maximum coverage. No thought was given to capacity issues.• Despite causing problems in high capacity networks, many of these high
sites are still in operation today.• Most cellular networks contain these nightmare sites.• When rolling out UMTS around an existing network it is vital to avoid these
UMTS Configurations• Most vendors support the same basic configurations.
• Omni• 3 sector• 6 sector
• Each vendor supports their own variations on these configurations.• Some solutions eliminate the need for RF plumbing.• Some require similar amounts of equipment to a GSM BTS.• Some increase the number of antennas on a site.
• The configuration can be affected by the wide variety of UMTS antennas.
Interference Issues• Wideband Noise - unwanted emissions from modulation process
and non-linearity of transmitter• Spurious Emissions - Harmonic, Parasitic, Inter-modulation products• Blocking - Transmitter carriers from another system• Inter-modulation Products - Spurious emission, specifications
consider this in particular• Active: non-linearities of active components - can be filtered out by BTS• Passive: non-linearities of passive components - cannot be filtered out by BTS
• Other EMC problems - feeders, antennas, transceivers and receivers