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9 Performance Aspects

The main features of mobile communication are the radio transmission between the MS and the BS and the use of the analog radio channel for digital data transmission. The analog channel „air“ leads to fading field strength, shadowing, attenuation, and interferences from co- and adjacent channels. In digital transmission this means high bit error rate, burst errors and time and location dependent fluctuation.
Because of the limited bandwidth only a small transmission rate can be achieved. The frequencies of GSM need to be reused making frequency planning an important task. The small number of channels per base station results from the small total number of channels and results in higher blocking probability. Together with the movement patterns this has to be taken into consideration for transmission power and power control, interference minimization, battery power control and EMC (ElectroMagnetic Compatibility) constraints.
On top there is a box with service performance. It is linked to 5 boxes in the row below, named service support performance, service operability performance, service access perfor-mance, service maintenance performance, and non-impairment of transmission. In the line be-low there are three boxes: Organization below service support performance, service below service operability performance and communication network as on big box below the three remaining boxes. 
Figure 9-1: Quality of telecommunication services from CCITT E.800.

Service support performance means the ability of one or more organizations to provide services tailored to the users and to support their use. The service support performance is judged by customer satisfaction, e.g. by customer interviews, complaints received by organizations or test from test-users. One can judge available tele, supplementary and value added services, available user equipment, installation, maintenance, helpdesk and planning of service subscription, prices for service subscription and usage, billing.
Service operability performance denotes the simplicity to use a service, including features of the user equipment, the comprehensibility of tones and messages. The operation is judged by frequency of wrong user reaction during a service by probability of errors setting up a service, calling the wrong number, stopping the attempt and stopping of dialing.
Service access performance denotes the ability of a service to stay between tolerable values while reaching the service.
Performance of service maintenance means the ability of a service to stay reachable for the wanted duration at an acceptable service level.
Non-impairment of a service gives the grade up to which a service (once reached) can be offered with accordable effort.

Users have the following performance criteria:
  • Speed – How long do they have to wait?
  • Accuracy – Is the execution correct?
  • Reliability – Can one rely on correct execution?
  • Mobility and movement – Where can the user access the communication? How mobile can the user be during the communication?
  • Security – Is the communication private and confident?
Tab. 9-1: Performance.
User oriented performance of
Access phase
 Information transfer phase
 Termination phase
Speed
Duration until
  • network answers
  • called terminal answers
  • first service access
Delay
Transmission rate
Throughput		Duration until next use of the service is possible
Accuracy

Rate of wrong connections

Transmission quality

 Probability of incorrect termination Difference to exact duration of use of service
Reliability
Probability for missing network answer
Blocking rate
Standby time for user equipment
 Rate for early service termination
Percentage of long disruption
Probability for information loss
Duration of terminal use

Denial of termination
Mobility and movement

Locations where the service can be used

 Coverage degree and performance
Max. speed of movement
Agility while service

 
Security

Measurement for protection of transmitted signaling information

 Measurement for protection of transmitted signaling information Measurement for confidentiality of transmitted user information

Measurement for protection of transmitted signaling information

Examples for performance criteria and target values for network oriented performance from GSM 02.08:
  • Time between service request and use (MS calling)
  •      BCCH known                                                                                4 s
  •      BCCH unknown                                                                          10 s
  • Rate of successful called services (MS calling)                           > 99%
  • Connection setup time between MS and PLMN border                    4 s
  • Time until confirmation of connection request                                   1 s
  • Time until connection termination between MS and PLMN border   2 s
  • Rate of successful called MS                                                       > 99%
  • Time until MS is activated (MS called)
  •      First attempt                                                                                 4 s
  •      Last attempt                                                                               15 s
  • Time until first use or change of a supplementary service              10 s
  • Interruption because of handover
  •      MSC-MSC handover                                                             150 ms
  •      BS-BS handover inside one MSC area                                 150 ms
  •      Change of channel inside one BS                                         100 ms
  •      Change of time slot inside one channel of one BS                100 ms
  •      Interruption of user data (if not caused by handover)              40 ms
  •      Rate of successful handovers                                                 > 99%

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