WaveSight TM - see your net work!
-
Upload
garry54 -
Category
Technology
-
view
349 -
download
0
Transcript of WaveSight TM - see your net work!
Introduction to the challengesof current GSM and GPRS planning
Technical PresentationTechnical Presentation
Slide 2Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
Wavecall SA
Prof. Dr. Fred Wagen
Senior Consultant
Wavecall SA
Lausanne, Switzerland
Prof. in telecommunication at the Univ. of Applied Sciences (HES-SO)
in Fribourg, Switzerland (www.eif.ch/telecom)
Slide 3Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
Outline
• GSM-vs-GPRS = circuit-vs-packet:so what ?
• GSM & GPRS planning: similarities and differences
• The crucial role of radio propagation prediction:
accurate model is a must• The challenges ahead:
prepare to react quickly
Slide 4Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
The challenges of GSM and GPRS planning
• GSM-vs-GPRS = circuit-vs-packet:so what ?
• GSM & GPRS planning: similarities and differences
• The crucial role of radio propagation prediction:
accurate model is a must• The challenges ahead:
prepare to react quickly
Slide 5Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS
GSM-vs-GPRS : so what ?
same TDMA-FDMA air interface …
BCCH
coul
d al
so b
e tra
ffic
slots
frequency
time
Slide 6Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM and GPRS
BCCH
GSM-vs-GPRS : so what ?
… but flexible multi-slots allocation for GPRS
GSMVoice
GPRS3 up
1 down
GPRS1 up
2 downthen 3 down
GPRS1 up
2 downthen 3 down
=> fewer empty slots
Slide 7Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : so what ?
GSM
Voice: a few errors can be tolerated but no delay
(< 200 ms)
SMS: store & forward
WAP: connecting …
data: 9.6 kbps CS or HSCSD on the move but not moving
Slide 8Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : so what ?
GPRS
Voice: ??? … may be for voice mail services
SMS: cheaper for operator and … users
WAP: … learn from i-mode
data: Packet Data, “always on” (claim or reality?)
Needs a new phone and a PC (laptop, palmtop), or
a PDA (Palm, EPOC, PocketPC,…), or a smart phone
(terminals withvoice recording)
Slide 9Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : Voice-vs-Data bearers
GSM voice GSM data13 kbps (Full Rate) 9.6 kbps
20 ms12.2 kbps (EFR)
20 ms 20 ms
260 bits (FR) 260 bits (FR) 192 bits+padding
Interleaving on 8 ½ bursts
R=1/2456 bits
R=1/2 R=1/2456 bits 456 bits
Interleaving on 4 bursts
2x57 bits2x57 bitsAverage 22.8 kbps per slot
270 kbps bursts on air interfaceAverage 22.8 kbps per slot
270 kbps bursts on air interface
Slide 10Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : GPRS Data
GPRS
9.05 kbps or 13.4 or 15.6 or 21.4 kbps
20 ms
181 bits or 268 or 312 or 428 bits
R=1/2 or 2/3 or 3/4 or no coding
CS1 or CS2 or CS3 or CS4456 bits
Similar to GSM data but
4 Coding Schemes
=> 4 data rates
Interleaving on 4 bursts
Average 22.8 kbps per slot270 kbps bursts on air interface
2x57 bits
Slide 11Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : coverage
GSM voice
Voice Quality(e.g.,MOS)
Analog voiceSufficient quality
Transmission quality
GSM
C/I
Goodenough
bad
9 to 12 dB
Slide 12Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : quality coverage
Quality is a subjective opinionGood
Threshold
Bad
Must be set by operator to quantify qualityand simplify the identification of problems.
Slide 13Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : coverage
GPRS : even more difficult
Voice Quality(e.g.,MOS)
Analog voiceSufficient quality
Transmission quality
GSM
C/I
Goodenough
bad
9 to 12 dB
Data ‘‘Quality’’(here bit rate)
CS1
CS2CS3
CS4GSM voice
C/I9 13 17 25 dB
Slide 14Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : coverage - urban
GPRSGSM voice
No coverage orother cell
coverageCS4
CS3CS1 CS2
2
3
3.5
4
9 kbps13 kbps
16 kbps
21 kbps
Urban environment
Slide 15Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : coverage - LOS
GSM voice GPRS
CS4
CS3
CS1
CS2
Free space
4
8
12
16
13 kbps
16 kbps
21 kbps
9 kbps
No coverage orother cell
coverage
Slide 16Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : so what ?
GSM-vs-GPRSRequirements for planning
Slide 17Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : Voice-vs-Data
GSM voice
13 kbps (Full Rate)
1 slot up / 1 slot down(total of 2)
Support ~1% FER
Plan coverage for voice service
GSM data
CS: 9.6 kbps (or 14.4 kbps)
HSCSD n*9.6 (or 14.4) kbps
1,2 or 3 slots up / 3, 2 or 1 slots down
(total of 4)
Error must be handled with ARQ
For users on the moveaccepting best effort service
and/or non-moving
Slide 18Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : so what ?
GSM voice
13 kbps (Full Rate)
1 slot up / 1 slot down(total of 2)
Support ~1% FER
Plan coverage for voice service
GPRS
Packet data
n*9 or *13 or *16 or *21 kbps
n = 1,2 or 3 slots up / 3, 2 or 1 slots down
(total of 4)
Errors must be handled with ARQ
Plan multi-coverage for new services
Slide 19Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM-vs-GPRS : so what ?
GSM voiceTraffic characteristics are “well known”
Quality is in fact a best effort service
butgood planning
lead to acceptable quality
GPRSTraffic characteristics are unknown
Quality depends on service profile:•Precedence class: indicates the importanceof the packet with regard to discarding it in case of problems and degradation of QoS when necessary.•Reliability class: specifies the mode of operation for various error detection and recovery protocols & how securely the datashould be delivered. •Delay class: specifies the transfer delay including the uplink radio channel access ordownlink radio channel scheduling delay, theradio channel transit delay, and GPRS network transit delay.•Peak throughput class: defines themaximum transfer rate.•Mean throughput class: defines the long term average transfer rate.
Slide 20Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
The challenges of GSM and GPRS planning
• GSM-vs-GPRS = circuit-vs-packet:so what ?
• GSM & GPRS planning: similarities and differences
• The crucial role of radio propagation prediction:
accurate model is a must• The challenges ahead:
prepare to react quickly
Slide 21Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM & GPRS planning: similarities & diff.
GPRS Number of subscribers ???
Traffic statistics ???+
??? simulation+
Reserve channels for GPRSif needed
combined planningWith GSM
Very difficult to planOffer best effort servicethen plan to be flexibleand follow the demand
GSM voiceNumber of subscribers
Traffic statistics+
Erlang B+
Add control channel if SMS traffic increases
Conventional planningStill not easy to plan when
exponential growth
Slide 22Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM & GPRS planning: similarities & diff.
GSM voice GPRS
“no drop” regions(e.g., indoor)
Blue = with indoor coverageRed = enhanced capacityGreen = GPRS capacityBrown = GPRS high throughput
handy coveragemust “work”
Slide 23Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM & GPRS planning: similarities & diff.
GSM voice GPRS
Coverage Traffic data
InterferenceMatrix
Tools Experience
FP (Frequency Plan)
C/I
OK
Yes, load FP in network
No
C/I
= propagationprediction
Coverage Traffic data
Interference
Matrix
Tools Experience
FP (Frequency Plan)
C/I
OK
Yes, load FP in network
No
C/I
Combine • GSM planning and • GPRS-CS1 to 4 analysis
Many more and fasteriterations are required
Slide 24Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
GSM & GPRS planning: similarities & diff.
GSM voice and GPRS
• Cannot be planned separately (… or consider full load).• Introduce GPRS “slowly” but be prepared for rapid take-off
(… “i-mode scenario”…):1. If easy user interfaces are developed (e.g., a mobile
internet button on every terminals),2. If appropriate charging is used (e.g., set-up time is either
short or not billed, flat rate combination),3. If the market can decide (open to innovative services).
• New Key Performance Indicators (KPI) must be developed and used.
• Tools must be as accurate and as easy to use as possible to concentrate on difficult tasks.
Slide 25Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
The challenges of GSM and GPRS planning
• GSM-vs-GPRS = circuit-vs-packet:so what ?
• GSM & GPRS planning: similarities and differences
• The crucial role of radio propagation prediction:
accurate model is a must• The challenges ahead:
prepare to react quickly
Slide 26Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
Radio propagation prediction
CoverageTraffic data
InterferenceMatrix
Tools Experience
FP
C/I
OK
Yes, load FP in network
No
C/I
Since GPRS traffic is unknown, only various scenarios can be investigated.Starting with a best-effort GPRS add-on to an existing GSM network, various growth scenarios must be taken into account orways to deploy rapidly the required level of “GPRS quality” must be found.In both cases, tools allowing to quickly and accurately assess the quality of a possible deployment are then critical.Proper coverage is key:=> accurate and fast radio propagation prediction model is a must in an integrated planning tool.
Slide 27Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
Radio propagation prediction
Conventional models.
•The smaller the cell the worse the inaccuracy.
•Need tuning => measurements => time.
•Need experience to mitigate the drawbacks.
•OK with GSM: took 10 years to be fully deployed.
Fast and accurate WaveSight.•Accuracy independent of cell size.
•No need for tuning.
•Need measurements to convince first time users.
•Allows to test various GSM-GPRS scenarios before field tests and deployment.
Slide 28Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
The challenges of GSM and GPRS planning
• GSM-vs-GPRS = circuit-vs-packet:so what ?
• GSM & GPRS planning: similarities and differences
• The crucial role of radio propagation prediction:
accurate model is a must• The challenges ahead:
prepare to react quickly
Slide 29Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
The challenges ahead: react quickly
! ! ! !
? Plan all possibilities ?
Or prepare to react quickly ?
Slide 30Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
The challenges ahead: react quickly
Everything may not work as expected :
⇒Suppress the guess work wherever you can⇒ accurate propagation predictions will help
Slide 31Prof. Dr. Volker Amelung / Dr. Karim Rizk Wavecall SA
Conclusion
GSM and GPRS have the same FDMA-TDMA air-interface.
But different coverage characteristics depending on data rate (Coding Scheme), on unused voice slots, and on expected or required user services.
Challenges are coming from the many unknowns.
Number of unknowns can be reduced by using more accurate planning tools wherever possible. Gather the proper tools, databases and methodology now !