K parameters
▪ K1 and K2 Intercept and Slope. These factors correspond to a constant offset (in
dBm) and a multiplying factor for the log of the distance between the base station
and mobile.
▪ K3 and K4 relate to the mobile height and how it affects the path loss. Since the
MS height is normally fixed (e.g. 1.5m) these two terms in the equation become
constants. They only require calibration if you employ a variable mobile height.
▪ K5 and K6 are very important parameters since they relate to the effective base
station antenna height, and how this affects the path loss. These values are difficult
to calibrate without gathering data at a wide variety of base station heights. The
default Hata values are K5=-13.82 and K6=-6.55. If sufficient data has been
gathered then these can be calibrated (one at a time) by an iterative process of
incremental changes and reanalysis until the standard deviation of the error is
minimized.
▪ K7 (Diffraction Parameter)
▪ Diffraction effects occur only where there is no line of sight (LOS) from the site to
the mobile. Therefore, in order to determine the K7 parameter the survey data
needs to be filtered to exclude the LOS data.
▪ All K parameters must keep the same polarity as in the original Okumura Hata model.
Asset uses slightly modified Okumura-Hata:
▫ Ploss =K1 + K2*log(d) + K3*Hms + K4*log(Hms) + K5*log(Heff) + K6*log(Heff)*log(d) + K7*Ldiff + Lclutter
▫ d is distance in km between Tx antenna and mobile station ▫ Hms is mobile station height
▫ Heff is effective antenna height in metres
▫ Ldiff is a loss due to diffraction, Lclutter is clutter loss.
The Purpose of a Model Tuning
• Characterise the topology with network limits – identification of operating range for
each model.
• Minimise Standard Deviation Error. •Provide zero mean error
• Determine model parameters in accordance to realistic propagation effects existing
within proposed regions.
• Make sure calibrated model corresponds well with the collected data – data is essential.
▪ To predict the receiving signal strength from a Base Station (BTS) ▪ To help with the Radio Plan without the need for an individual CW measurement verification
▪ Most steps in the planning of a network are highly dependent on the accuracy of the model. e.g.
▪ Coverage
▪ Traffic Analysis ▪ Frequency Planning ▪ Parameter Analysis
Propagation Model
The advanced GSM/CDMA/WCDMA technological features and various services have attracted many subscribers and telecom operators. Study and modeling of the radio wave propagation model is the
foundation of network planning, and is also the foundation of link and coverage estimation. The accuracy of the propagation model directly influences the scale of radio network planning, the accuracy of
coverage estimation, and the layout of Node Bs.
Aware of the importance of propagation model’s accuracy, mPraxis has been devoted to the study of propagation model,and achieved rich experiences in practice.
In propagation model tuning, we simulate the test result with the field strength of the test point and the line between the test point and the transmitter, when transmission power and reception power are known. Usually, the final result of model tuning fulfills an average error of 0 and a minimal standard deviation. Here we use tools like Asset to make propagation model tuning.
CW Drive Tests
We perform Continuous Wave (CW) testing at various locations
throughout the network to provide better insight into the radio signal’s propagation characteristics at these locations. This testing consists of installing the CW receiver equipment in a test vehicle and driving
specified routes intended for coverage by a wireless site if constructed at the test transmitter location. The purpose of this testing is to
measure the propagation of defined radio signals (at known TX power level, locations and frequency) to develop a baseline model. The
equipment used to transmit and receive should remain consistent
throughout all of the drive tests. Accuracy of the propagation modeling requires parameters of the test site configuration to be recorded
accurately for each drive test performed. We support this activity by wither using Agilent Kit, Invex 3G kit sot TEMS kits.
Nominal Cell Plan
Nominal Cell Plan using standard planning tools for UMTS, GSM and CDMA like Asset, Cell Plan, Planet, Net Plan we determine
1. Demand forecast service and location of demand. Outline desired area of coverage defined by Client via maps or software.
2. Develop coverage objectives. Prepare coverage plan to meet objectives. Define building coverage penetration requirement for “Urban”, “Suburban” and “Rural”. Define GSM Link Budget
3. Generate coverage plots
4. Document and distribute radio base station dependent data. Identify the following cell site information based on client’s coverage and capacity design requirements:
• Number of voice channels. • Effective radiated power.
• Antenna radiation centre above ground level (AGL). • Sector/omni antenna and orientations.
• Down-tilt angle • Frequency plan
• Site name, site code and number
• Provide map co-ordinates of base stations. • Create Cell Design Data (CDD) for each site.
5. Frequency plan based on data collected in item 5 above. 6. Prepare & submit nominal Cell Plan on ASSET and Frequency
Plan.
7. Approve the nominal cell plan 8. Issue search rings
RF Survey of Search Area/ MW LOS survey and selection of suitable site candidates
• Obtain general building information • Taking digital photos
• Technical site survey (TSS) and preparation of the RF part of the TSS report
• Performing line of sight (LOS) surveys for sites that are connected via MW links using Pathloss tools.
• Preparation of site layout (from RF and MW transmission point of view), including information on antenna heights, antenna
directions, location of the BTS and any other special needs to be captured for a particular site
• Approval of the site layout through the Customer and contribution of the layout to the site folder
