Tech talk of Institute of Technology

1. Mobile
Communication
Access Network Concepts

2. Vendors
No of 2G sites
No of 3G sites
No of 4G FDD sites
No of 4G TDD sites
No of Indoor Sites
Area - 700 km2
Borders – Panadura River , Kelaniya River, Awissawella

3. 1G to 5G....
 Simplex
 Semi Duplex
 Full Duplex
Transmission Modes in Mobile System
First Generation, 1G
Introduced in 1982 and completed in early 1990. It was used for voice services and was
based on technology called as Advanced Mobile Phone System (AMPS). The AMPS
system was frequency modulated and used frequency division multiple access (FDMA)
with a channel capacity of 30 KHz and frequency band of 824-894MHz.
Discussion

4. 1G to 5G....
Second Generation (2G)
2G refers to the second generation based on GSM and was emerged in late 1980s. It uses digital signals for voice
transmission. Main focus of this technology was on digital signals and provides services to deliver text and picture
message at low speed (in kbps). It use the bandwidth of 30 to 200 KHz
Third Generation (3G)
3G is based on GSM and was launched in 2000. The aim of this technology was to offer high speed data. The original
technology was improved to allow data up to 14 Mbps and more using packet switching. It uses Wide Band Wireless
Network with which clarity is increased. It operates at a range of 2100MHz and has a bandwidth of 15-20MHz used for
High-speed internet service
Fourth Generation (4G)
4G offers a downloading speed of 100Mbps. 4G provides same feature as 3G and additional services like Multi-Media
Newspapers, to watch T.V programs with more clarity and send Data much faster than previous generations. LTE (Long
Term Evolution) is considered as 4G technology. 4G is being developed to accommodate the QoS and rate
requirements set by forthcoming applications like wireless broadband access, Multimedia Messaging Service (MMS),
video chat, mobile TV, HDTV content, Digital Video Broadcasting (DVB).
Fifth Generation (5G)

5.  Mobile Comm. Principles
MSISDN - Mobile Station International Subscriber Directory Number
IMSI
They provide the right call, right service
IMSI = MCC+MNC+MSIN -An international mobile subscriber identity (IMSI)
MCC = Mobile Country Code
MNC = Mobile Network Code
MSIN = Mobile Sucscriber Identification Number

6. Mobile System Different Environments
Global
Suburban
Macro-Cell
Urban
Micro-Cell
In- Building
Pico-Cell
Home-Cell

7. GSM (Global System for Mobile communications) - 2.5G

9. GSM Variants
Discussion
ARFCN
Channel No
Operator Spectrum Allocation
Frequency Reuse
One tower
Capacity
Half Rate/Full Rate
Discussion
4+4+4 Configuration
Spectrum Limitation
Solution – Hopping
Multiple Access Techniques
FDMA
TDMA

10. Discussion
BCCH Frequency - BCCH TRX
Hopping Frequency - Hopping TRX
Discussion
Call Flow – BCCH+SDCCH+TCH
HSN e MAIO

11. GSM Channels

12. Co-channel interference and adjacent channel interference
Receiving a call to You
Neighbors

13. Power Scenarios
Watt To dBm
Idle Mode Behavior
Example GSM C1 Calculator & GSM C2 Calculator :
Inputs: Rx Level (Average) = -85 dBm, Rx Level (Access
min) = -100 , CRO (Cell Reselect Offset) = 6 dB, TO
(Temporary Offset) = 3 dB, Penalty time = ( 0 or 1)
Outputs:
➨C1 = 15
➨C2 = C1 - CRO = 9(When Penalty time is not reached
i.e. Penalty time =0 )
➨C2 = C1 + CRO-TO*H(PT-T) (When Penalty time is
reached i.e. Penalty time =1 )
C2 = 15 + 6 -3 = 18

14. Dedicate Mode Behavior
Different Layers
Neighbor Relations
Hand Over
DCS- 1800
Different Antenna
Coverage Layer
TEMS Training – 2G
Capacity plan
Erlangs
Erlangs B Table
Diversity
Antenna Pattern

15. KPIs – 2G
Issues Analysis
Coverage plan
Customer solution

16. Coverage Solutions
Post
Pre

17. Quality Solutions
Case Analysis

18. Events Capacity Plan

19. Exercise – Capacity Plan
1. Calls
2. SMS
3. Handover In
4. Handover Out
5. From 3G to 2G
6. SMS during Calls
7. Idle Selected
8. Vehicle moving through LAC
9. Call initiated
10. LAC update in 2 Hours
11. Call terminated

20. Developed by the global GSM community to support third-generation (3G)
mobile services, WCDMA is the designated air interface for one of the
International Telecommunications Union’s (ITU’s) family of 3G mobile
communications systems. WCDMA is used in the radio leg of both UMTS and
HSPA networks.
As well as supporting conventional voice, text and MMS services, WCDMA
(Wideband Code Division Multiple Access) can carry data at high speeds,
enabling mobile operators to deliver richer mobile multimedia services such
as music-on-demand, TV and video streaming and broadband Internet
access.

21. URFCN -
Calculation

22. What is Spread Spectrum?
➢ Transmission bandwidth is much larger than the information bandwidth
➢ Bandwidth is not dependent of the information signal
➢ Channelization codes used for channel separation from a single source
➢ same codes in all cells ==> need for scrambling
➢ Scrambling codes separate
➢ Uplink: different mobiles
➢ Downlink: different cells/sectors
➢ Have good interference averaging (correlation) properties
WCDMA Codes
Ec/No
Noise
CPICH

24. Think about your car radio. There are more than a dozen (or so) channels on the radio at any time, each with a
given frequency: 100.1 MHz, 102.5 MHz etc... Each channel gets a certain range (usually about 0.22 MHz)
we can transmit multiple signals simultaneously over a single channel
Long Distance Travel
Antenna Design
Communication Systems/What is Modulation?
Types of Modulation
Amplitude modulation.
Frequency modulation
Phase modulation

26. Limitation
➢ DL Power
➢ UL Power
➢ Channel Element
➢ RTWP
➢ Code Limitation

29. Orthogonal codes
 All pairwise cross correlations are zero
 For CDMA application, each mobile user uses one sequence in the set as a spreading code
 Provides zero cross correlation among all use

31. KPIs

32. In UMTS, in each slot the maximum number of bits transmitted is 2560. The correct term to use is
chips rather than bits.
There are 15 slots per 10ms frame so since the TTI for HSDPA is 2ms, there will be 3 slots. So there will
be a total of 7680 chips.
QPSK has 2 bits per symbol = 7680 * 2 chips for 2ms = 15360 chips/2ms = 15360 * 1000 /2 chips per
second
Now the SF is fixed at 16
= (15360 * 1000) / (2 * 16)
= 480 Kbps
Terminal that uses 15 QPSK codes will get 480 * 15 = 7.2Mbps
On other hand 16 QAM will have 4 bits per symbol so the rate would be 7.2 * 2 = 14.4Mbps
Wideband Code-Division Multiple Access systems, the standard rate is 3.84 Mcps

34. 2G General Packet Radio Service (GPRS)
Enhanced Data Rates for GSM Evolution 384 kbit/s
114 kbit/s 20 kbit/s
60 kbit/s
3G HSDPA/HSUPA 7.2/ 14.4 /21 / 42 Mbit/s
100 Mbps/150 Mbps
4G LTE (20Mhz)
2 Mbit/s
75 Mbit/s

35. Frequency Division vs. Time Division Duplexing in Wireless Communications
FDD – Mobile wireless tech.
Wireless systems need two separate frequency bands or channels. A sufficient amount of guard band separates the two
bands so the transmitter and receiver don’t interfere with one another.
TDD – Fixed wireless tech.
TDD uses a single frequency band for both transmit and receive. Then it shares that band by assigning alternating time slots
to transmit and receive operations

36. Frequency Division vs. Time Division Duplexing in Wireless Communications
4G
3G

37. Parameters Description
Duplexing FDD, TDD, half-duplex FDD
Channel coding Turbo code
Mobility 350 km/h
Channel Bandwidth (MHz) •1.4 3,5,10,15,20
Modulation Schemes UL: QPSK, 16QAM, 64QAM(optional)
DL: QPSK, 16QAM, 64QAM
Multiple Access Schemes UL: SC-FDMA (Single Carrier Frequency Division Multiple Access) supports
50Mbps+ (20MHz spectrum)
DL: OFDM (Orthogonal Frequency Division Multiple Access) supports 100Mbps+
(20MHz spectrum)
Multi-Antenna Technology UL: Multi-user collaborative MIMO
DL: TxAA, spatial multiplexing, CDD ,max 4x4 array
Peak data rate in LTE UL: 75Mbps(20MHz bandwidth)
DL: 150Mbps(UE Category 4, 2x2 MIMO, 20MHz bandwidth)
DL: 300Mbps(UE category 5, 4x4 MIMO, 20MHz bandwidth)
MIMO
(Multiple Input Multiple Output)
UL: 1 x 2, 1 x 4
DL: 2 x 2, 4 x 2, 4 x 4
Coverage 5 - 100km with slight degradation after 30km
QoS E2E QOS allowing prioritization of different class of service
Latency End-user latency < 10mS

38. L1800
L900
L2100
------------------------------------------------------
L2300
FDD
TDD

39. VoLTE (voice over LTE) refers to voice calls that are made over a 4G LTE network instead of more traditional
calls
Discussion…
• Volte
• CSFB
• SRVCC
• RRC redirection

44. Access Network Planning ….
Scope – Planning , Quality, CX solutions, Data speed, Budget , New Innovation ,
Working with BU & ND
Working with NOT and DNS

45. Infrastructure
Spectrum Sharing
Small Cells
RAN Sharing