This is the last step of the network planning procedure. It can start during the network trial period and continues after opening the commercial service and during the network expansion.
The aim of this process is to evaluate and maximize the quality of service in the network with the corresponding set of quality criteria.
Network verificationThe purpose of the network verification (NV) is to evaluate an independent and objective quality of service (QOS) inside a given service area. This is done with network measurement system. Some OMC traffic measurements are dine in parallel to provide a statistical data and to complete the network picture.
The network verification procedure consists of the following steps:
• Planning of the measurement resources (including tools), reference network, schedule and test route(s)
• Setting of the network performance objectives and quality criteria
• Measurement execution and analysis of the statistical results
• Reporting to the customer the results of analysis
• Agreement on possible corrective actions if the set quality criteria is not met
The field verification takes place after successful completion of site acceptance. It should be repeated before and after any major network hardware/software changes to verify their affect on the network quality.
The service area, or the part of the network to be verified, is defined as a group of cells giving continuous coverage. It is always connected with a selection of test routes; the all verification and optimization activities are based in recurrent measurements over the same routes.
Network quality criteriaThe quality objectives are specified according to the capacity requirements and customer’s QOS strategy which se agreed with the customer.
One basic requirement for Network quality survey is to monitor continuously QOS and Hp behavior, compare the network against other similar network and present the result in such a way that they are easy to understand for non-technical parts of the operator’s organization as well. To be capable of doing that requires additional metrics that are sensitive enough and very easy to understand.
Analysis of the Results
The main result of the verification procedure is the statistical quality sheet generated by the NPS/X or similar system
In addition to the statistical quality sheet the network element availability statistics from the OMC also form part of the network verification results. These results are collected either on a monthly or weekly basis and they concern the network elements as a whole or by unit basis. The statistics of unit restarts and the availability of transceiver units are reported.
The congestion level of each BTS is obtained from the OMC traffic statistics and reported together with other network Verification results as the Network Verification report
Network OptimizationNetwork Optimization can be defined as a continuous process of improving overall network quality. Looking at network quality two different views should be considered . The customers (subscribers) view and the more comprehensive operators view fig. 1 overall network quality is illustrating this.
Usually a subscriber is not interested in site leasing or maintenance socts. As long as his service is not affected things like spectrum efficiency and network traffic are of no interest to him. For the operator these fig are of fundamental importance.
Network optimization service and more general the Nokia Quality cycle service package are designed to support the operator in the most efficient way to improve all different aspects of network quality. Nokia tools experts with detailed system knowledge and the global network of experience provide the operator with the most sophisticated services.
BSS Default Parameter AssessmentsProper BSS default parameter settings are needed to ensure the best possible performance of the network. The parameter sets are based on experience from optimized networks.
BSS Configuration Analysis ModuleNetwork configuration Analysis is the smallest possible service module of network optimization. With this service the system configuration as existing in the real network (system configuration network) is compared against the system configuration as provided by network planning. This task ensures consistency between different system configuration databases and therefore is the basis of all following tasks. Basic configuration analysis should be repeated on a regular basis. Nokia can support with improving or designing and implementing procedures for regular consistency checks.
Basic Network Optimization ModuleField-tests OMC measurements and customer complaints are the three main sources to provide a detailed network quality picture.(e.g. call and handover success rates, problems reported by customer and field test personnel) the network performance data analysis together with single quality improvement actions raise network quality on a case by case basis. These tasks are combined in the Basic Network Optimization Module.
Full Optimization ServiceAs network optimization has to be seen as part of a bigger process, which is embedded in the operator’s organization, Nokia is offering services and consultancy in the area of quality definition monitoring and improvement. This service sis called Full Optimization service and contains the small quality cycle as described in the previous chapter.
As the small quality cycle is required to monitor and improve quality on a more or less problem-by-problem basis a more global approach of quality monitoring and improvement is required.
Global quality reporting on regional and network level is required for management marketing and network planning. Global quality monitoring is similar to quality monitoring as required for Basic network optimization but it is reporting on a more general level (field tests, OMC and customer complaints) Global quality reporting allows
To monitor the impact of major changes in the network (e.g. frequency changes, BSS default parameter changes or massive traffic increase)
Quality definition and quality target setting are needed for agreements between different departments (e.g. Planning and marketing) As a conclusion from global quality reporting and experience from the small quality cycle work general improvement actions (e.g. testing new system features) and general corrective actions (e.g. major frequency change , capacity extension , introduction of micro cells or IUO)might follow.
In all phases of the network quality cycle Nokia is supporting with consultancy tools and training
Optimization ToolsNokia is providing a variety of tools for network optimization. NMS/X, Nokia network measurement system for GSM/DCS and NMT network quality survey, network tracing and for multi channel field strength measurements covers all demands for field measurements. A portable version allows indoor measurements.
NPS/X, Nokia network planning system, is also a powerful tool for network optimization. Its features for down and uploading data from the OMC, the GSM/DCS simulator, the link to the measurement system NMS/X and many other features provide the optimization personnel with an advanced tool.
Examples For Basic Cell Planning Input from the customer
Total subscribers 10000 at 25 mE traffic
Total Traffic 250 E (10000 X 25 mE)
Grade of service 2 %
Operating frequency 900 MHz
Hypothetical distribution of traffic is:
Case 1: for specified number of sites
• 1/1/1 sites (350 subs per site)……..7000 subscribers.
• 2/2/2 sites (990 subs per site)……..19800 subscribers
Case 2: for specified capacity requirement (10000)
• 1/1/1 sites…….. 10000/350….. 30 sites
• 2/2/2 sites…….. 10000/990…...11 sites
Deciding Factors - Planning
• We may choose 2/2/2 sites for first 3 area types and 1/1/1 sites for the rest.
• What is the area of coverage needed?
• How many sites are required for this area?
(cell radius of 1 km means an approximate coverage area of 3 Sq.kms).
• Do we need so many sites?
• Can some sites be bigger?
• Decide number of sites based on capacity and coverage requirements.
• Divide city into clutter types such as:
1. Urban
2. Suburban
3. Quasi open
4. Open
5. Water
• Identify “search areas” covering all clutter types.
• Customer selects a few sample sites
• Survey sites with reference to
1. Clutter heights
2. Vegetation levels
3. Obstructions
4. Sector orientation
5. Building strengths and other civil requirements.
• Prepare power budgets.
• Conduct propagation tests.
• Calculate coverage probabilities based on the drive test results.
• Verify power budget sensitivity against drive test results modify planning tool parameter
• Prepare final coverage map.
RF planning starts with the preparation a power budget for the up link and the downlink for all sites.
Assume
Frequency 900MHzs
Cell radius 5 Kms
BTS antenna height 30m
Mobile antenna height 3m
Required receiver
Sensitivity (RSS) -104 dBm (BTS) and –102 dBm (MS)
So path loss for above inputs is 147.23 dB (calculated using Okumara-Hata urban propagation model)
