Deepak Joshi, profile picture
Uploaded byDeepak Joshi
PPT, PDF20,087 views

GSM capacity planning

This document discusses capacity planning for GSM networks. It covers topics like trunking, traffic theory including traffic intensity, grade of service, busy hour, and request rate. It describes how to dimension traffic channels and SDCCH channels based on factors like traffic intensity and grade of service. It also discusses connectivity planning between network elements like MSC, BSC, transcoder, and BTS. It provides details on air interface, Abis interface between BSC and BTS, and different LAPD modes for signaling concentration over Abis. The objective is to estimate the optimal number of resources needed to meet performance requirements based on traffic analysis and engineering principles.

Embed presentation

Downloaded 1,278 times
GSM Network Capacity Planning Trunking Traffic Theory -- Traffic Intensity -- Grade of Service Traffic Channels Dimensioning SDCCH Channels Dimensioning Company Confidential 15/7/05 1
Trunking LOCAL GATEWAY SWITCH SWITCH So, What is the objective behind Capacity Planning ? Estimating the optimum number of resources required in a system to meet the desired performance requirements. Company Confidential 15/7/05 2
Traffic Theory Terminologies Traffic Intensity Busy Hour Request Rate ( BHCA ) Set-up Time Holding Time Blocked Call Grade of Service (GoS) Company Confidential 15/7/05 3
Traffic Theory Traffic Intensity TRAFFIC INTENSITY IS MEASURED ON 1 CALL PER-HOUR BASIS OR 1 CALL PER MINUTE BASIS THE UNIT OF MEASUREMENT IS ERLANGS Au = uH Au : Traffic in Erlang generated by each user H : Average duration of call / 60 (per hour basis) u : Average no of calls per hour A = UAu A : Total traffic offered by the system U : Total number of users Company Confidential 15/7/05 4
Traffic Theory Traffic Intensity ... Contd. In GSM, we have two types of Traffic Intensities TCH Traffic Intensity = Avg no of calls x Avg duration of call Average duration of call = 120 secs Average number of calls = 0.75 -- 1.5 ( range ) Traffic generated on TCH will range between 0.025 -- 0.05 erlang Company Confidential 15/7/05 5
Traffic Theory Traffic Intensity ... contd and ... SDCCH Traffic Intensity = Avg no of SDCCH usages x Avg usage time Avg no of SDCCH usage = 1(for a TCH call) + 3 updates = 4 Average usage time = 4 secs Traffic generated on SDCCH will be typically 0.0044 erlang Company Confidential 15/7/05 6
Traffic Theory Busy Hour 1 Hour of the day in which Traffic is maximum Also referred to as Peak Hour. Busy Hour is not a fixed hour, its timing will vary in different locations Busy Hour may also be different for different resources SDCCH busy hour -- typically morning hours ( frequent on/offs and updates) TCH busy hour -- heavy call traffic hour ( could be back-home hours ) Company Confidential 15/7/05 7
Traffic Theory Request Rate ( BHCA ) No of requests(or attempts) for a resource in the busy hour SDCCH Request Rate -- No of RACH's + No of Handover Requests for SDCCH TCH Request Rate -- No of RACH's in a cell with cause as MOC or MTC + No of Handover Request for TCH Company Confidential 15/7/05 8
Traffic Theory Set up Time Average time spent on a resource before getting response from the called end. Typically 3 - 5 secs for GSM ( up to POI setup) Holding Time Average time spent on any dedicated resource. SDCCH Holding time ( typically 3 - 4 secs) TCH Holding time ( actuall call duration + Alerting ) Company Confidential 15/7/05 9
Traffic Theory Blocked Call A call request rejected due to unavailability of resource. Indication of Congestion In GSM a call can be blocked due to unavailability of : AGCH SDCCH TCH How many blocked calls can you tolerate ? Company Confidential 15/7/05 10
Traffic Theory Grade of Service Percentage requests blocked in an hour Ability of the user to access the system during busiest hour Benchmark to define desired system performance GOS and blocking are same. A network is non-blocking if the communication resources equals the number of users. Conventionally used value of GOS is 2 % Company Confidential 15/7/05 11
TYPES OF TRUNKING SYSTEM Blocked Calls Cleared System Requested is immediately cleared (forgotten) at blocking Erlang B table is used to estimate traffic for a GOS No. of Capacity (Erlangs) for GOS channels C = 1% = 1.5 % =2% = 5% 2 .153 .190 .223 .381 7 2.50 2.74 2.94 3.74 8 3.13 3.40 3.63 4.54 14 7.35 7.82 8.20 9.73 15 8.11 8.61 9.01 10.6 16 8.88 9.41 9.83 11.5 22 13.7 14.3 14.9 17.1 30 20.3 21.2 21.9 24.8 37 26.4 27.4 29.6 31.6 Company Confidential 15/7/05 12
There are two types of trunked systems which are commonly used. The first type offers no queuing for call requests.That is, for every user who request service, it is assumed there is no setup time and the user is given immediate access to a channel if one is available. If no channels are available, the requesting user is blocked without access and is free to try again later. This type of trunking is called blocked calls cleared. It is assumed that there are infinite number of users and there are memory less arrivals of requests, there are finite number of channels available.The capacity of a radio adopting this concept is tabulated for various values of GOS. Company Confidential 15/7/05 13
Types of Trunking Systems Assumptions deciding Erlang B table : A request for channel may come at any time. All free channels are fully available for servicing calls until all channels are occupied. Call durations are exponentially distributed. Longer calls are less likely to happen. Traffic requests also follows exponentially distribution of inter-arrival times. Mulitple requests will not occur at regular intervals. Inter-arrival times of call requests from different users are independent of each other. There are finite number of channels available in the trunking pool. Company Confidential 15/7/05 14
Types of Trunking Systems Blocked Calls Delayed System GOS ( delay calls) = exp ( - ( C - A ) t / H ) C = No of channels, A = Traffic Intensity obtained from chart, t = Time (secs ) for which call is delayed H = Average duration of calls GOS ( blocked delayed calls ) = GOS x GOS (delay calls) GOS = Targetted GOS Company Confidential 15/7/05 15
The second type of trunked system is one in which a queue is provided to hold calls which are blocked.If a channel is not available immediately,the call request may be delayed until a channel becomes available. This type of trunking is called Blocked Calls Delayed,and the GOS in this case is defined as the probability that a call is blocked after waiting a specific length of time in the queue.If no channels are immediately available the call is delayed .The GOS for delayed system is calculated by the formula shown above. The first formula calculates the percentage of calls that will be delayed for a period (t) for a traffic intensity A (which is calculated from the chart keeping a target GOS) . The second formula calculates the percentage of blocking after a delay of t seconds, that is percentage of attempts denied after being queued for t seconds. Company Confidential 15/7/05 16
Traffic Channel Dimensioning Calculation of no of TCH required in a cell* depends on : GOS & Traffic Intensity Traffic Intensity = No of users x Traffic Intensity per user No of users depends on demographic data as : Population Distribution Car usage distribution Income Fixed Line data Service cost Mobile Phone cost * Cell area depends on propagation factors Company Confidential 15/7/05 17
Estimating No of users and Traffic Example : Car usage distribution 4L streets = 1.1 Km 1L 2L streets = 2.1 km 1L 1L 1L streets = 6.4 km 2L Avg Spacing between vehicles = 10m 2L Total vehicles in 100% street congestion case 1L 4L = 1500 2L For 50% penetration = 750 users 1L Traffic = 750 x 0.025 = 18.5 erl; corresponds to 27 TCH's Company Confidential 15/7/05 18
Estimating Channels from last case Traffic Intensity = 750 x 0.025 = 18.5 erlangs At GOS of 2 %, we need 27 TCH's & 9 SDCCH's. A cell configured with 4 ARFCN with B+D & 1 D config, will provide 12 SDCCH's and 30 TCH's which satisfies. Another method of achieving is with 2 sectors, each having 2 ARFCN's , with B & D config, which will give 8 SDCCH and 14 TCH in each sectored cell . Company Confidential 15/7/05 19
Cell Configuration 1L 1L 1L 2L 2L 1L 4L 2L 1L Company Confidential 15/7/05 20
CONNECTIVITY PLANNING Company Confidential 15/7/05 21
WHAT TO CONNECT ? MSC ----- PSTN MSC ----- BSC MSC ----- TRANSCODER * BSC ----- TRANSCODER * BSC ----- BTS Company Confidential 15/7/05 22
Speech on Terrestrial circuit BSC Transcoder BTS Abis A S 0 1 2 3 S 0 1 2 3 16 Kbps 16 Kbps S 13 Kbps 64 Kbps 0 1 A 2 3 MSC Company Confidential 15/7/05 23
Air Interface 13 Kbps BTS TCH/SDCCH are the traffic resources 8 PCHN on 1 ARFCN Minimum 1 PCHN required for CCCH / and SDCCH 1 ARFCN gives 7 TCH max and 4 SDCCH min. TCH's and SDCCH's can be altered by adding carriers and channel configurations Company Confidential 15/7/05 24
Abis Interface E1 / T1 Abis is a G.703 interface. It could be E1 or T1 Abis carriers Traffic information of all the mobiles in the cells controlled by the BTS. Abis also carries signaling information between BTS and BSC Signaling over Abis is done by LAPD protocols LAPD has several modes of implementation --- LAPD --- LAPD Concentrated --- LAPD Multiplexed Each TCH/F on Air Interface requires 16kbps sub-channel on Abis. 16 kbps subchannel on Abis is a nailed connection also known as RTF Company Confidential 15/7/05 25
Abis is the PCM interface between the BSC and MSC. Physically this is a G.703 interface and could be E1 or T1. in all our further discussions we will consider E1. Abis carrier the traffic and signaling information for all the transceivers inside the BTS. It also carries O&M information between the BSC and BTS, like the control commands coming from the BSC and traffic reports originated by the BTS. Abis used the HDLC protocol for signaling which is LAPD ( Link Access Protocol on D channel ). LAPD has several modes of operation. What modes means is how the signaling circuits are distributed over the E1 interface, whether each TRX has separate signaling circuits or several TRX signaling information is concentrated or multiplexed on limited signaling circuits. Company Confidential 15/7/05 26
Abis Interface LAPD Modes LAPD Signaling for each TRX is on a dedicated 64 Kbps circuit Maximum Signalling for 10 Transceivers on 1 E1 link 64 kbps 0 Sync 64 kbps 1 TRX Signaling 64 kbps 2 4 Traffic Channels 64 kbps 3 4 Traffic Channels } 1 TRX 64 kbps 4 TRX Signaling 64 kbps 5 4 Traffic Channels 64 kbps 6 4 Traffic Channels } 1 TRX 64 kbps 7 TRX Signaling 64 kbps 8 4 Traffic Channels 64 kbps 9 4 Traffic Channels } 1 TRX Company Confidential 15/7/05 27
The first LAPD mode illustrated above is the LAPD basic mode. In this mode each TRX has a separate signaling circuit of 64 Kbps. Each signaling circuit has two immediate 64 Kbps Traffic circuits. GSM used 13 kbps of speech rate on the air interface, to which some TRAU information is added and it becomes 16 Kbps. Four such 16 kbps traffic channels are mapped on one 64 Kbps circuit. Each TRX has 8 traffic channels. So for each Transceiver, two 64 kbps circuits are required, one for Traffic and one for Signaling. With this mode, 10 Transceivers can be accommodated on one E1. Company Confidential 15/7/05 28
Abis Interface LAPD Modes LAPD Concentrated mode 1 Signaling for 4 TRX's is on a dedicated 64 Kbps ciruit Maximum Signalling for 13 Transceivers on 1 E1 link 64 kbps 0 Sync 64 kbps 1 4 x TRX Signaling 64 kbps 2 4 Traffic Channels 64 kbps 3 4 Traffic Channels } 1 TRX 64 kbps 4 4 Traffic Channels 64 kbps 5 4 Traffic Channels } 1 TRX 64 kbps 6 4 Traffic Channels 64 kbps 7 4 Traffic Channels } 1 TRX 64 kbps 8 4 Traffic Channels 64 kbps 9 4 Traffic Channels } 1 TRX 64kbps 10 4 x TRX Signaling Company Confidential 15/7/05 29
In this mode which is LAPD Concentrated Signaling information for certain number of TRX's are concentrated on a single 64 kbps circuit. There are two different methods of concentration. The above figure illustrates one method in which on one 64 kbps circuit the signaling information for 4 TRX's are concentrated. This is typically done by creating 16 kbps subchannels. So with this method 13 TRXs signaling as well as speech can be accommodated on a single E1 Link. Company Confidential 15/7/05 30
Abis Interface LAPD Modes LAPD Concentrated mode 2 Signaling for All TRX's is on a dedicated 64 Kbps circuit Maximum Signaling for 15 Transceivers on 1 E1 link 64 kbps 0 Sync 64 kbps 1 ALL TRX Signaling 64 kbps 2 4 Traffic Channels 64 kbps 3 } 1 TRX 4 Traffic Channels 64 kbps 4 4 Traffic Channels 64 kbps 5 } 1 TRX 4 Traffic Channels 64 kbps 6 4 Traffic Channels 64 kbps 7 } 1 TRX 4 Traffic Channels 64 kbps 8 4 Traffic Channels 64 kbps 9 4 Traffic Channels } 1 TRX 64 kbps 10 4 Traffic Channels Company Confidential 15/7/05 31
In this type of concentrated LAPD mode , signaling for all the Transcevier are concentrated on one 64 kbps circuit. With this, 15 TRX's signaling and Speech can be accommodated on 1xE1 link. This method is becoming very popular and is adopted by many of the NEMS. Company Confidential 15/7/05 32
Abis Interface LAPD Modes LAPD Multiplexed Signaling for each TRX is on 16kbps subchannel. Maximum signaling for 15 TRX's on 64 kbps 0 Sync 64 kbps 1 TRX Signaling/ 3 Traffic Channels } 1 TRX 64 kbps 2 4 Traffic Channels 64 kbps 3 TRX Signaling/ 3 Traffic Channels 64 kbps 4 4 Traffic Channels } 1 TRX 64 kbps 5 TRX Signaling/ 3 Traffic Channels 64 kbps 6 4 Traffic Channels } 1 TRX 64 kbps 7 TRX Signaling/ 3 Traffic Channels 64 kbps 8 4 Traffic Channels } 1 TRX 64 kbps 9 TRX Signaling/ 3 Traffic Channels 64 kbps 10 4 Traffic Channels } 1 TRX Company Confidential 15/7/05 33
LAPD multiplexed is a mode in which Signaling for each TRX is on a 16 kbps circuit which is multiplexed with 3 speech channels of 16 Kbps. So for each TRX two 64 kbps circuits are required. Company Confidential 15/7/05 34
Abis Interface Capacity Capacity on Abis is the number of 64 kbps circuits required For Local Transcoding Capacity = No of TCH at BTS + No LAPD signaling circuits + OML* For Remote Transcoding Capacity = No of TCH at BTS / 4 + No LAPD signalling circuits + OML* Capacity = Number of 64 kbps circuits No of TCH = Sum of all TCH's in each sector at the BTS No of LAPD circuits = Depends on LAPD mode OML = optional ( vendor dependent ) Company Confidential 15/7/05 35
Abis Interface Capacity Example 1 cell = 15 x 16 kbps speech channels 3 cells = 45 x 16 kbps speech channels = 12 x 64 kbps speech channels 15 speech ch 1 BTS = 12 + 1 ( RSL ) = 13 x 64 kbps channels C1 BSC C3 C2 15 speech ch 15 speech ch Company Confidential 15/7/05 36
The BSC to BTS Link is connected by E1 signaling system,which uses a 2.048 Mbps stream with 32 x 64kbps channels. The link between the BSC to BTC is termed as Radio Signaling Link. In a sectorial cell configuration, one BTS supports 3 cells. Take a case where each cell has 2 carriers which means there are 16 physical channels in this cell. With only one channel reserved for control, 15 channels will be available for speech. So for one BTS with 3 cells, will have 45 speech channels of 16 kbps, each will in turn occupy 12 channels of 64 kbps on the RSL Link. That is, including the RSL channel which occupies 1 x 64 kbps slot on the link, overall 13 x 64 kbps channels are required for 1 BTS. Company Confidential 15/7/05 37
Exercise !!! A BTS has 3 sectored cells. Each cell has a subscriber capacity of 600, calculate the number of TCH and SDCCH required at GOS 2 % and also calculate the capacity on the Abis interface with LAPD concentrated mode 2 signaling. Company Confidential 15/7/05 38
BSC Capacity Maximum BTS's Capacity on "A" interface Company Confidential 15/7/05 39
BSC Capacity Maximum BTS's No of BTS's supported by the BSC is vendor specific It is generally based on either or both of below : 1. Maximum number of TRX's BSC can support (in terms of traffic) 2. Maximum number of PCM interfaces BSC can support. Max PCM interfaces can be optmized by selecting BTS configurations Company Confidential 15/7/05 40
BSC Capacity BTS configuration Star Configuration BTS BTS BTS BSC BTS BTS Company Confidential 15/7/05 41
BSC Capacity BTS configuration Chain Configuration BSC BTS BTS 26 x 64 kbps 13 x 64 kbps ch ch 1 x E1 1 x E1 Company Confidential 15/7/05 42
BSC Capacity BTS configuration Loop configuration BTS A A B BSC B A B BTS A B Company Confidential 15/7/05 43
Exercise ! Each BTS needs 13 x 64 kbps circuits H BTS BTS BTS I BTS B BTS C L BTS N J K A BTS D BTS BSC BTS M E BTS G O BTS F BTS BTS BTS Calculate the Number of E1 Links for each of the links ? Company Confidential 15/7/05 44
BSC Capacity Capacity on "A" Interface Capacity on A interface depends on Traffic of BSC at targeted GOS. Traffic of BSC = No of Subscribers under BSC x Traffic per Subscriber From calculated traffic, using Erlang B table calculate the number of circuits required. For Local Transcoding Capacity = No of Speech Circuits + Signaling Circuits For Remote Transcoding Capacity = No of Speech Circuits/4 + Signaling Circuits Company Confidential 15/7/05 45
BSC Capacity Signalling Circuit Capacity on A interface Signaling circuits SS7 "A" Link : Used for MSC - BSC signaling OML : For OMC TBL : Transcoder BSC Link Capacity for SS7 link Calculate the BHCA per second BHCA : No of SDCCH attempts ( call+updates) x No of Subscribers . On average each attempt requires 6 signaling messages No of messages per second = 6 x BHCA per second On average each message is of 25 octets Capacity of Signaling circuit ( kbps ) = 25octets x No of messages per second Company Confidential 15/7/05 46
Transcoder - MSC Cpacity TRANS BSC MSC CODER = 1 x E1 = 112 x 16 kbps chs = 1 x E1 = 30 x 64 kbps chs 4 x E1 = 120 x 64 kbps chs Company Confidential 15/7/05 47
BSC to MSC link also uses E1 signaling structure. The above figure considers the case for remote transcoding.The capacity of the BSC to Transcoder link should be planned out on the basis of number of BTS connected to the BSC. The BSC to transcoder is an E1 link having 32 channels, out of which; 1 for MSC signaling 1 for OMC signaling 1 for Transcoder signalling 1 for sync. So 28 channels are left out for speech which are 64kbps each so this will result into 112 x 16kbps speech channels. After transcoding these 16 kbps channels will map on to 64 kbps channels, so for 1 x 16 kbps channel coming to the transcoder will become 1 x 64 kbps channel going towards MSC. That is 112 x 16 kbps channels will require a capacity of 112 x 64kbps on the MSC link, which will result into 4 E1. Company Confidential 15/7/05 48
MSC Capacity MSC Capacity = No of Subscribers x Traffic per subscriber Long term calculation is based on Population Penetration --- Population Penetration is the mobile population out of total population of PLMN ( city ) Population Penetration = Total Population x Penetration rate MSC Capacity = Population Penetration x Traffic per subscriber Example : For a city population of 10,000000 with penetration rate of 2 %. Population Penetration = 200000 MSC Capacity = 10,000 Erlangs Company Confidential 15/7/05 49
Network Elements Capacity MSC - PSTN Link Capacity --- Estimate the % of PSTN calls from Total calls --- Calculate the PSTN Traffic based on above estimation --- Set a GOS --- Calculate the no of channels by using Erlang B Table Company Confidential 15/7/05 50

More Related Content

DOC
Gsm Frequency Planning
byDeepak Sharma
 
PDF
2G Optimization
byMelika Poursamar
 
PPTX
Part 2 planning of 3G
byHenry Chikwendu
 
PPT
TEMS PARAMETERS
byTempus Telcosys
 
PPT
GSM fundamentals (Huawei)
byShopnomoy Prantor
 
PPT
WCDMA RF optimization
bybasioni
 
PDF
Nokia dictionary
byJetal Patel
 
PPT
GSM Channel concept and SDCCH
byDeepak Joshi
 
Gsm Frequency Planning
byDeepak Sharma
 
2G Optimization
byMelika Poursamar
 
Part 2 planning of 3G
byHenry Chikwendu
 
TEMS PARAMETERS
byTempus Telcosys
 
GSM fundamentals (Huawei)
byShopnomoy Prantor
 
WCDMA RF optimization
bybasioni
 
Nokia dictionary
byJetal Patel
 
GSM Channel concept and SDCCH
byDeepak Joshi
 

What's hot

DOCX
Lte drive test parameters
byKamalsyah Abdurrahman
 
PPT
3 g huawei-wcdma-rno-parameters-optimization
byshagahod
 
PDF
VoLTE optimization.pdf
byRakhiJadav1
 
PPTX
422738668-LTE-Downlink-Throughput-Optimization-Based-on-Performance-Data [Rep...
bySudheeraIndrajith
 
PDF
LTE-RF Drive test .pdf
byssuser3be61c1
 
PDF
Hw lte rf-optimization-guide
bytharinduwije
 
PPT
Lte ho parameters trial_01262011
byHatim100
 
PPT
Lte rf-optimization-guide
byMuhammad Ahsan
 
PDF
Umts access kpi troubleshooting guide rrc
byPrashant Gaurav
 
PPT
01 lte radio_parameters_lte_overview_rl1
byMd.Akm Sahansha
 
DOCX
Lte coverage optimization analysis
byArnoldus Leo Karra
 
PPT
Part 3 optimization 3G
byHenry Chikwendu
 
PDF
LTE KPI
bySitha Sok
 
DOCX
Layer 3 messages
byJohn Samir
 
PPT
63077585 idle-mode-parameter-optimization
byRanto Narivo Solofo RAFARALAHY
 
PPTX
NSN NOKIA 3G KPI for Network planning and optimization
byYogender Singh Rana
 
PPT
Ericsson 2 g ran optimization complete training
bysekit123
 
PDF
LTE Review - Load Balancing and Interfreq HO
bypaulo_campolina
 
PDF
Irat handover basics
byBamidele Odediya
 
PDF
Lte system signaling procedures
bytharinduwije
 
Lte drive test parameters
byKamalsyah Abdurrahman
 
3 g huawei-wcdma-rno-parameters-optimization
byshagahod
 
VoLTE optimization.pdf
byRakhiJadav1
 
422738668-LTE-Downlink-Throughput-Optimization-Based-on-Performance-Data [Rep...
bySudheeraIndrajith
 
LTE-RF Drive test .pdf
byssuser3be61c1
 
Hw lte rf-optimization-guide
bytharinduwije
 
Lte ho parameters trial_01262011
byHatim100
 
Lte rf-optimization-guide
byMuhammad Ahsan
 
Umts access kpi troubleshooting guide rrc
byPrashant Gaurav
 
01 lte radio_parameters_lte_overview_rl1
byMd.Akm Sahansha
 
Lte coverage optimization analysis
byArnoldus Leo Karra
 
Part 3 optimization 3G
byHenry Chikwendu
 
LTE KPI
bySitha Sok
 
Layer 3 messages
byJohn Samir
 
63077585 idle-mode-parameter-optimization
byRanto Narivo Solofo RAFARALAHY
 
NSN NOKIA 3G KPI for Network planning and optimization
byYogender Singh Rana
 
Ericsson 2 g ran optimization complete training
bysekit123
 
LTE Review - Load Balancing and Interfreq HO
bypaulo_campolina
 
Irat handover basics
byBamidele Odediya
 
Lte system signaling procedures
bytharinduwije
 

Similar to GSM capacity planning

PPT
Switching systems lecture3
byJumaan Ally Mohamed
 
PPTX
Unit 3
byDeepakkumar5880
 
PDF
Wireless traffic theory and handoff
byMunaf Rashid
 
PPTX
Lecture5 teletraffic
bymazlina1202
 
PDF
Teletraffic engineering handbook
byDeepak Singh
 
PDF
Lecture 3 trunking theory and other issues with cells
byUmairKhalil16
 
PPTX
Telephone Traffic Engineering Online Lec
byfllcampolet
 
PPTX
Traffic analysis
bySrashti Vyas
 
PPT
Chapter7 te cet533
bythisa93
 
PPTX
Trunking Theory
bypirh khan
 
PPTX
wireless communication chapterr 2 part 2
bykingdahireditor
 
PPTX
3-cc8e98a4b1-u3_ch_5_traffic-engineering.pptx
byIvanUssivane
 
PPTX
Teletraffic engineeringTeletraffic engineers use their knowledge (2).pptx
byMdSharifUddinShajib
 
PPTX
nothing to share for networking orm.pptx
byamalsura101
 
PDF
Wireless communications principles_and_p
bySara El Filali
 
PPT
Implementation of Forward Scheduling (GOS Factor) on BSC 6600 CDMA EvDO Rev.A
byRay KHASTUR
 
PPTX
M & WC unit 1.pptx very good condition and success
by20EC040
 
PDF
G010613135
byIOSR Journals
 
PDF
Litrature Survey of Traffic Analysis and Congestion Modeling In Mobile Network
byiosrjce
 
PPTX
idea
byIsha Chhaya
 
Switching systems lecture3
byJumaan Ally Mohamed
 
Unit 3
byDeepakkumar5880
 
Wireless traffic theory and handoff
byMunaf Rashid
 
Lecture5 teletraffic
bymazlina1202
 
Teletraffic engineering handbook
byDeepak Singh
 
Lecture 3 trunking theory and other issues with cells
byUmairKhalil16
 
Telephone Traffic Engineering Online Lec
byfllcampolet
 
Traffic analysis
bySrashti Vyas
 
Chapter7 te cet533
bythisa93
 
Trunking Theory
bypirh khan
 
wireless communication chapterr 2 part 2
bykingdahireditor
 
3-cc8e98a4b1-u3_ch_5_traffic-engineering.pptx
byIvanUssivane
 
Teletraffic engineeringTeletraffic engineers use their knowledge (2).pptx
byMdSharifUddinShajib
 
nothing to share for networking orm.pptx
byamalsura101
 
Wireless communications principles_and_p
bySara El Filali
 
Implementation of Forward Scheduling (GOS Factor) on BSC 6600 CDMA EvDO Rev.A
byRay KHASTUR
 
M & WC unit 1.pptx very good condition and success
by20EC040
 
G010613135
byIOSR Journals
 
Litrature Survey of Traffic Analysis and Congestion Modeling In Mobile Network
byiosrjce
 
idea
byIsha Chhaya
 

Recently uploaded

PDF
Building Voice Agents with Google Agent Development Kit
bySuresh Peiris
 
PDF
MINDCTI Revenue Release Quarter 3 2025 - Financial Presentation
byMIND CTI
 
PPT
Telecommunication system introduction to wireless communication
by143irha
 
PDF
Teaching Robots how to Read 1/2: AI Center & Classic Document Understanding (...
byanabulhac
 
PPTX
CodeMash 2026 - Optimizing Azure App Services
byBrian McKeiver
 
PPTX
Spacewalk 2026 - Presented at the IMAX in Raleigh, NC
byAll Things Open
 
PPTX
Storage-and-HCI-Positioning-update-sales.pptx
byhungungphu123
 
PDF
UiPath Coded Agents - A Developer Driven Agentic Automation Era
byUiPathCommunity
 
PDF
Français Patch Tuesday - Janvier
byIvanti
 
PDF
Presentation of Cybersecurity and data protection
bytarikaityahya2
 
PDF
How Automation Powers Data Quality and Governance at Scale
bySafe Software
 
PDF
Transcript: What ONIX can do: Leveraging metadata to support the discoverabil...
byBookNet Canada
 
PDF
Computer Science Conferences 2026 | Research by SAI Conference
byHealth Conference 2026
 
PPTX
Fortify Your Digital Defenses with ServiceNow Security Operations by Suma Soft
byGavin Ellis
 
PPT
Database Management Systems: Basics, History, Data Models, etc.
byParithi Thamizh
 
PPTX
The Abomination of AI – keynote at ICoSCI 2026
byAlan Dix
 
PDF
Unlocking Gen AI Capabilities Within UiPath Document Understanding
byDianaGray10
 
PPT
connectives-linking words in English.ppt
byAmrMohammed82
 
PPTX
AI Meets DBA Transforming Database Administration with Intelligence
byGeoPITS Global Pvt Ltd
 
PPTX
computer science class 11 ( phishing and fraud mails) .pptx
bybalajichess314
 
Building Voice Agents with Google Agent Development Kit
bySuresh Peiris
 
MINDCTI Revenue Release Quarter 3 2025 - Financial Presentation
byMIND CTI
 
Telecommunication system introduction to wireless communication
by143irha
 
Teaching Robots how to Read 1/2: AI Center & Classic Document Understanding (...
byanabulhac
 
CodeMash 2026 - Optimizing Azure App Services
byBrian McKeiver
 
Spacewalk 2026 - Presented at the IMAX in Raleigh, NC
byAll Things Open
 
Storage-and-HCI-Positioning-update-sales.pptx
byhungungphu123
 
UiPath Coded Agents - A Developer Driven Agentic Automation Era
byUiPathCommunity
 
Français Patch Tuesday - Janvier
byIvanti
 
Presentation of Cybersecurity and data protection
bytarikaityahya2
 
How Automation Powers Data Quality and Governance at Scale
bySafe Software
 
Transcript: What ONIX can do: Leveraging metadata to support the discoverabil...
byBookNet Canada
 
Computer Science Conferences 2026 | Research by SAI Conference
byHealth Conference 2026
 
Fortify Your Digital Defenses with ServiceNow Security Operations by Suma Soft
byGavin Ellis
 
Database Management Systems: Basics, History, Data Models, etc.
byParithi Thamizh
 
The Abomination of AI – keynote at ICoSCI 2026
byAlan Dix
 
Unlocking Gen AI Capabilities Within UiPath Document Understanding
byDianaGray10
 
connectives-linking words in English.ppt
byAmrMohammed82
 
AI Meets DBA Transforming Database Administration with Intelligence
byGeoPITS Global Pvt Ltd
 
computer science class 11 ( phishing and fraud mails) .pptx
bybalajichess314
 

GSM capacity planning

  • 1.
    GSM Network CapacityPlanning Trunking Traffic Theory -- Traffic Intensity -- Grade of Service Traffic Channels Dimensioning SDCCH Channels Dimensioning Company Confidential 15/7/05 1
  • 2.
    Trunking LOCAL GATEWAY SWITCH SWITCH So, What is the objective behind Capacity Planning ? Estimating the optimum number of resources required in a system to meet the desired performance requirements. Company Confidential 15/7/05 2
  • 3.
    Traffic Theory Terminologies Traffic Intensity Busy Hour Request Rate ( BHCA ) Set-up Time Holding Time Blocked Call Grade of Service (GoS) Company Confidential 15/7/05 3
  • 4.
    Traffic Theory Traffic Intensity TRAFFIC INTENSITY IS MEASURED ON 1 CALL PER-HOUR BASIS OR 1 CALL PER MINUTE BASIS THE UNIT OF MEASUREMENT IS ERLANGS Au = uH Au : Traffic in Erlang generated by each user H : Average duration of call / 60 (per hour basis) u : Average no of calls per hour A = UAu A : Total traffic offered by the system U : Total number of users Company Confidential 15/7/05 4
  • 5.
    Traffic Theory TrafficIntensity ... Contd. In GSM, we have two types of Traffic Intensities TCH Traffic Intensity = Avg no of calls x Avg duration of call Average duration of call = 120 secs Average number of calls = 0.75 -- 1.5 ( range ) Traffic generated on TCH will range between 0.025 -- 0.05 erlang Company Confidential 15/7/05 5
  • 6.
    Traffic Theory Traffic Intensity... contd and ... SDCCH Traffic Intensity = Avg no of SDCCH usages x Avg usage time Avg no of SDCCH usage = 1(for a TCH call) + 3 updates = 4 Average usage time = 4 secs Traffic generated on SDCCH will be typically 0.0044 erlang Company Confidential 15/7/05 6
  • 7.
    Traffic Theory Busy Hour 1 Hour of the day in which Traffic is maximum Also referred to as Peak Hour. Busy Hour is not a fixed hour, its timing will vary in different locations Busy Hour may also be different for different resources SDCCH busy hour -- typically morning hours ( frequent on/offs and updates) TCH busy hour -- heavy call traffic hour ( could be back-home hours ) Company Confidential 15/7/05 7
  • 8.
    Traffic Theory Request Rate( BHCA ) No of requests(or attempts) for a resource in the busy hour SDCCH Request Rate -- No of RACH's + No of Handover Requests for SDCCH TCH Request Rate -- No of RACH's in a cell with cause as MOC or MTC + No of Handover Request for TCH Company Confidential 15/7/05 8
  • 9.
    Traffic Theory Set upTime Average time spent on a resource before getting response from the called end. Typically 3 - 5 secs for GSM ( up to POI setup) Holding Time Average time spent on any dedicated resource. SDCCH Holding time ( typically 3 - 4 secs) TCH Holding time ( actuall call duration + Alerting ) Company Confidential 15/7/05 9
  • 10.
    Traffic Theory Blocked Call A call request rejected due to unavailability of resource. Indication of Congestion In GSM a call can be blocked due to unavailability of : AGCH SDCCH TCH How many blocked calls can you tolerate ? Company Confidential 15/7/05 10
  • 11.
    Traffic Theory Grade ofService Percentage requests blocked in an hour Ability of the user to access the system during busiest hour Benchmark to define desired system performance GOS and blocking are same. A network is non-blocking if the communication resources equals the number of users. Conventionally used value of GOS is 2 % Company Confidential 15/7/05 11
  • 12.
    TYPES OF TRUNKINGSYSTEM Blocked Calls Cleared System Requested is immediately cleared (forgotten) at blocking Erlang B table is used to estimate traffic for a GOS No. of Capacity (Erlangs) for GOS channels C = 1% = 1.5 % =2% = 5% 2 .153 .190 .223 .381 7 2.50 2.74 2.94 3.74 8 3.13 3.40 3.63 4.54 14 7.35 7.82 8.20 9.73 15 8.11 8.61 9.01 10.6 16 8.88 9.41 9.83 11.5 22 13.7 14.3 14.9 17.1 30 20.3 21.2 21.9 24.8 37 26.4 27.4 29.6 31.6 Company Confidential 15/7/05 12
  • 13.
    There are twotypes of trunked systems which are commonly used. The first type offers no queuing for call requests.That is, for every user who request service, it is assumed there is no setup time and the user is given immediate access to a channel if one is available. If no channels are available, the requesting user is blocked without access and is free to try again later. This type of trunking is called blocked calls cleared. It is assumed that there are infinite number of users and there are memory less arrivals of requests, there are finite number of channels available.The capacity of a radio adopting this concept is tabulated for various values of GOS. Company Confidential 15/7/05 13
  • 14.
    Types of TrunkingSystems Assumptions deciding Erlang B table : A request for channel may come at any time. All free channels are fully available for servicing calls until all channels are occupied. Call durations are exponentially distributed. Longer calls are less likely to happen. Traffic requests also follows exponentially distribution of inter-arrival times. Mulitple requests will not occur at regular intervals. Inter-arrival times of call requests from different users are independent of each other. There are finite number of channels available in the trunking pool. Company Confidential 15/7/05 14
  • 15.
    Types of TrunkingSystems Blocked Calls Delayed System GOS ( delay calls) = exp ( - ( C - A ) t / H ) C = No of channels, A = Traffic Intensity obtained from chart, t = Time (secs ) for which call is delayed H = Average duration of calls GOS ( blocked delayed calls ) = GOS x GOS (delay calls) GOS = Targetted GOS Company Confidential 15/7/05 15
  • 16.
    The second typeof trunked system is one in which a queue is provided to hold calls which are blocked.If a channel is not available immediately,the call request may be delayed until a channel becomes available. This type of trunking is called Blocked Calls Delayed,and the GOS in this case is defined as the probability that a call is blocked after waiting a specific length of time in the queue.If no channels are immediately available the call is delayed .The GOS for delayed system is calculated by the formula shown above. The first formula calculates the percentage of calls that will be delayed for a period (t) for a traffic intensity A (which is calculated from the chart keeping a target GOS) . The second formula calculates the percentage of blocking after a delay of t seconds, that is percentage of attempts denied after being queued for t seconds. Company Confidential 15/7/05 16
  • 17.
    Traffic Channel Dimensioning Calculation of no of TCH required in a cell* depends on : GOS & Traffic Intensity Traffic Intensity = No of users x Traffic Intensity per user No of users depends on demographic data as : Population Distribution Car usage distribution Income Fixed Line data Service cost Mobile Phone cost * Cell area depends on propagation factors Company Confidential 15/7/05 17
  • 18.
    Estimating No ofusers and Traffic Example : Car usage distribution 4L streets = 1.1 Km 1L 2L streets = 2.1 km 1L 1L 1L streets = 6.4 km 2L Avg Spacing between vehicles = 10m 2L Total vehicles in 100% street congestion case 1L 4L = 1500 2L For 50% penetration = 750 users 1L Traffic = 750 x 0.025 = 18.5 erl; corresponds to 27 TCH's Company Confidential 15/7/05 18
  • 19.
    Estimating Channels fromlast case Traffic Intensity = 750 x 0.025 = 18.5 erlangs At GOS of 2 %, we need 27 TCH's & 9 SDCCH's. A cell configured with 4 ARFCN with B+D & 1 D config, will provide 12 SDCCH's and 30 TCH's which satisfies. Another method of achieving is with 2 sectors, each having 2 ARFCN's , with B & D config, which will give 8 SDCCH and 14 TCH in each sectored cell . Company Confidential 15/7/05 19
  • 20.
    Cell Configuration 1L 1L 1L 2L 2L 1L 4L 2L 1L Company Confidential 15/7/05 20
  • 21.
    CONNECTIVITY PLANNING Company Confidential 15/7/05 21
  • 22.
    WHAT TO CONNECT? MSC ----- PSTN MSC ----- BSC MSC ----- TRANSCODER * BSC ----- TRANSCODER * BSC ----- BTS Company Confidential 15/7/05 22
  • 23.
    Speech on Terrestrialcircuit BSC Transcoder BTS Abis A S 0 1 2 3 S 0 1 2 3 16 Kbps 16 Kbps S 13 Kbps 64 Kbps 0 1 A 2 3 MSC Company Confidential 15/7/05 23
  • 24.
    Air Interface 13 Kbps BTS TCH/SDCCH are the traffic resources 8 PCHN on 1 ARFCN Minimum 1 PCHN required for CCCH / and SDCCH 1 ARFCN gives 7 TCH max and 4 SDCCH min. TCH's and SDCCH's can be altered by adding carriers and channel configurations Company Confidential 15/7/05 24
  • 25.
    Abis Interface E1 / T1 Abis is a G.703 interface. It could be E1 or T1 Abis carriers Traffic information of all the mobiles in the cells controlled by the BTS. Abis also carries signaling information between BTS and BSC Signaling over Abis is done by LAPD protocols LAPD has several modes of implementation --- LAPD --- LAPD Concentrated --- LAPD Multiplexed Each TCH/F on Air Interface requires 16kbps sub-channel on Abis. 16 kbps subchannel on Abis is a nailed connection also known as RTF Company Confidential 15/7/05 25
  • 26.
    Abis is thePCM interface between the BSC and MSC. Physically this is a G.703 interface and could be E1 or T1. in all our further discussions we will consider E1. Abis carrier the traffic and signaling information for all the transceivers inside the BTS. It also carries O&M information between the BSC and BTS, like the control commands coming from the BSC and traffic reports originated by the BTS. Abis used the HDLC protocol for signaling which is LAPD ( Link Access Protocol on D channel ). LAPD has several modes of operation. What modes means is how the signaling circuits are distributed over the E1 interface, whether each TRX has separate signaling circuits or several TRX signaling information is concentrated or multiplexed on limited signaling circuits. Company Confidential 15/7/05 26
  • 27.
    Abis Interface LAPD Modes LAPD Signaling for each TRX is on a dedicated 64 Kbps circuit Maximum Signalling for 10 Transceivers on 1 E1 link 64 kbps 0 Sync 64 kbps 1 TRX Signaling 64 kbps 2 4 Traffic Channels 64 kbps 3 4 Traffic Channels } 1 TRX 64 kbps 4 TRX Signaling 64 kbps 5 4 Traffic Channels 64 kbps 6 4 Traffic Channels } 1 TRX 64 kbps 7 TRX Signaling 64 kbps 8 4 Traffic Channels 64 kbps 9 4 Traffic Channels } 1 TRX Company Confidential 15/7/05 27
  • 28.
    The first LAPDmode illustrated above is the LAPD basic mode. In this mode each TRX has a separate signaling circuit of 64 Kbps. Each signaling circuit has two immediate 64 Kbps Traffic circuits. GSM used 13 kbps of speech rate on the air interface, to which some TRAU information is added and it becomes 16 Kbps. Four such 16 kbps traffic channels are mapped on one 64 Kbps circuit. Each TRX has 8 traffic channels. So for each Transceiver, two 64 kbps circuits are required, one for Traffic and one for Signaling. With this mode, 10 Transceivers can be accommodated on one E1. Company Confidential 15/7/05 28
  • 29.
    Abis Interface LAPD Modes LAPD Concentrated mode 1 Signaling for 4 TRX's is on a dedicated 64 Kbps ciruit Maximum Signalling for 13 Transceivers on 1 E1 link 64 kbps 0 Sync 64 kbps 1 4 x TRX Signaling 64 kbps 2 4 Traffic Channels 64 kbps 3 4 Traffic Channels } 1 TRX 64 kbps 4 4 Traffic Channels 64 kbps 5 4 Traffic Channels } 1 TRX 64 kbps 6 4 Traffic Channels 64 kbps 7 4 Traffic Channels } 1 TRX 64 kbps 8 4 Traffic Channels 64 kbps 9 4 Traffic Channels } 1 TRX 64kbps 10 4 x TRX Signaling Company Confidential 15/7/05 29
  • 30.
    In this modewhich is LAPD Concentrated Signaling information for certain number of TRX's are concentrated on a single 64 kbps circuit. There are two different methods of concentration. The above figure illustrates one method in which on one 64 kbps circuit the signaling information for 4 TRX's are concentrated. This is typically done by creating 16 kbps subchannels. So with this method 13 TRXs signaling as well as speech can be accommodated on a single E1 Link. Company Confidential 15/7/05 30
  • 31.
    Abis Interface LAPD Modes LAPD Concentrated mode 2 Signaling for All TRX's is on a dedicated 64 Kbps circuit Maximum Signaling for 15 Transceivers on 1 E1 link 64 kbps 0 Sync 64 kbps 1 ALL TRX Signaling 64 kbps 2 4 Traffic Channels 64 kbps 3 } 1 TRX 4 Traffic Channels 64 kbps 4 4 Traffic Channels 64 kbps 5 } 1 TRX 4 Traffic Channels 64 kbps 6 4 Traffic Channels 64 kbps 7 } 1 TRX 4 Traffic Channels 64 kbps 8 4 Traffic Channels 64 kbps 9 4 Traffic Channels } 1 TRX 64 kbps 10 4 Traffic Channels Company Confidential 15/7/05 31
  • 32.
    In this typeof concentrated LAPD mode , signaling for all the Transcevier are concentrated on one 64 kbps circuit. With this, 15 TRX's signaling and Speech can be accommodated on 1xE1 link. This method is becoming very popular and is adopted by many of the NEMS. Company Confidential 15/7/05 32
  • 33.
    Abis Interface LAPD Modes LAPD Multiplexed Signaling for each TRX is on 16kbps subchannel. Maximum signaling for 15 TRX's on 64 kbps 0 Sync 64 kbps 1 TRX Signaling/ 3 Traffic Channels } 1 TRX 64 kbps 2 4 Traffic Channels 64 kbps 3 TRX Signaling/ 3 Traffic Channels 64 kbps 4 4 Traffic Channels } 1 TRX 64 kbps 5 TRX Signaling/ 3 Traffic Channels 64 kbps 6 4 Traffic Channels } 1 TRX 64 kbps 7 TRX Signaling/ 3 Traffic Channels 64 kbps 8 4 Traffic Channels } 1 TRX 64 kbps 9 TRX Signaling/ 3 Traffic Channels 64 kbps 10 4 Traffic Channels } 1 TRX Company Confidential 15/7/05 33
  • 34.
    LAPD multiplexed isa mode in which Signaling for each TRX is on a 16 kbps circuit which is multiplexed with 3 speech channels of 16 Kbps. So for each TRX two 64 kbps circuits are required. Company Confidential 15/7/05 34
  • 35.
    Abis Interface Capacity Capacityon Abis is the number of 64 kbps circuits required For Local Transcoding Capacity = No of TCH at BTS + No LAPD signaling circuits + OML* For Remote Transcoding Capacity = No of TCH at BTS / 4 + No LAPD signalling circuits + OML* Capacity = Number of 64 kbps circuits No of TCH = Sum of all TCH's in each sector at the BTS No of LAPD circuits = Depends on LAPD mode OML = optional ( vendor dependent ) Company Confidential 15/7/05 35
  • 36.
    Abis Interface Capacity Example 1 cell = 15 x 16 kbps speech channels 3 cells = 45 x 16 kbps speech channels = 12 x 64 kbps speech channels 15 speech ch 1 BTS = 12 + 1 ( RSL ) = 13 x 64 kbps channels C1 BSC C3 C2 15 speech ch 15 speech ch Company Confidential 15/7/05 36
  • 37.
    The BSC toBTS Link is connected by E1 signaling system,which uses a 2.048 Mbps stream with 32 x 64kbps channels. The link between the BSC to BTC is termed as Radio Signaling Link. In a sectorial cell configuration, one BTS supports 3 cells. Take a case where each cell has 2 carriers which means there are 16 physical channels in this cell. With only one channel reserved for control, 15 channels will be available for speech. So for one BTS with 3 cells, will have 45 speech channels of 16 kbps, each will in turn occupy 12 channels of 64 kbps on the RSL Link. That is, including the RSL channel which occupies 1 x 64 kbps slot on the link, overall 13 x 64 kbps channels are required for 1 BTS. Company Confidential 15/7/05 37
  • 38.
    Exercise !!! A BTShas 3 sectored cells. Each cell has a subscriber capacity of 600, calculate the number of TCH and SDCCH required at GOS 2 % and also calculate the capacity on the Abis interface with LAPD concentrated mode 2 signaling. Company Confidential 15/7/05 38
  • 39.
    BSC Capacity Maximum BTS's Capacity on "A" interface Company Confidential 15/7/05 39
  • 40.
    BSC Capacity Maximum BTS's No of BTS's supported by the BSC is vendor specific It is generally based on either or both of below : 1. Maximum number of TRX's BSC can support (in terms of traffic) 2. Maximum number of PCM interfaces BSC can support. Max PCM interfaces can be optmized by selecting BTS configurations Company Confidential 15/7/05 40
  • 41.
    BSC Capacity BTS configuration Star Configuration BTS BTS BTS BSC BTS BTS Company Confidential 15/7/05 41
  • 42.
    BSC Capacity BTS configuration ChainConfiguration BSC BTS BTS 26 x 64 kbps 13 x 64 kbps ch ch 1 x E1 1 x E1 Company Confidential 15/7/05 42
  • 43.
    BSC Capacity BTS configuration Loopconfiguration BTS A A B BSC B A B BTS A B Company Confidential 15/7/05 43
  • 44.
    Exercise ! EachBTS needs 13 x 64 kbps circuits H BTS BTS BTS I BTS B BTS C L BTS N J K A BTS D BTS BSC BTS M E BTS G O BTS F BTS BTS BTS Calculate the Number of E1 Links for each of the links ? Company Confidential 15/7/05 44
  • 45.
    BSC Capacity Capacity on"A" Interface Capacity on A interface depends on Traffic of BSC at targeted GOS. Traffic of BSC = No of Subscribers under BSC x Traffic per Subscriber From calculated traffic, using Erlang B table calculate the number of circuits required. For Local Transcoding Capacity = No of Speech Circuits + Signaling Circuits For Remote Transcoding Capacity = No of Speech Circuits/4 + Signaling Circuits Company Confidential 15/7/05 45
  • 46.
    BSC Capacity Signalling CircuitCapacity on A interface Signaling circuits SS7 "A" Link : Used for MSC - BSC signaling OML : For OMC TBL : Transcoder BSC Link Capacity for SS7 link Calculate the BHCA per second BHCA : No of SDCCH attempts ( call+updates) x No of Subscribers . On average each attempt requires 6 signaling messages No of messages per second = 6 x BHCA per second On average each message is of 25 octets Capacity of Signaling circuit ( kbps ) = 25octets x No of messages per second Company Confidential 15/7/05 46
  • 47.
    Transcoder - MSCCpacity TRANS BSC MSC CODER = 1 x E1 = 112 x 16 kbps chs = 1 x E1 = 30 x 64 kbps chs 4 x E1 = 120 x 64 kbps chs Company Confidential 15/7/05 47
  • 48.
    BSC to MSClink also uses E1 signaling structure. The above figure considers the case for remote transcoding.The capacity of the BSC to Transcoder link should be planned out on the basis of number of BTS connected to the BSC. The BSC to transcoder is an E1 link having 32 channels, out of which; 1 for MSC signaling 1 for OMC signaling 1 for Transcoder signalling 1 for sync. So 28 channels are left out for speech which are 64kbps each so this will result into 112 x 16kbps speech channels. After transcoding these 16 kbps channels will map on to 64 kbps channels, so for 1 x 16 kbps channel coming to the transcoder will become 1 x 64 kbps channel going towards MSC. That is 112 x 16 kbps channels will require a capacity of 112 x 64kbps on the MSC link, which will result into 4 E1. Company Confidential 15/7/05 48
  • 49.
    MSC Capacity MSC Capacity = No of Subscribers x Traffic per subscriber Long term calculation is based on Population Penetration --- Population Penetration is the mobile population out of total population of PLMN ( city ) Population Penetration = Total Population x Penetration rate MSC Capacity = Population Penetration x Traffic per subscriber Example : For a city population of 10,000000 with penetration rate of 2 %. Population Penetration = 200000 MSC Capacity = 10,000 Erlangs Company Confidential 15/7/05 49
  • 50.
    Network Elements Capacity MSC- PSTN Link Capacity --- Estimate the % of PSTN calls from Total calls --- Calculate the PSTN Traffic based on above estimation --- Set a GOS --- Calculate the no of channels by using Erlang B Table Company Confidential 15/7/05 50