Cellular Networks Lecture 6 Paul Flynn

Cellular Telephony - Architecture

Very Basic Cellular/PCS Architecture Mobility Database Public Switched Telephone Network Base Station Controller Mobile Switching Center (MSC) Radio Network Base Station (BS) Mobile Station

Duplex Communication - FDD FDD: Frequency Division Duplex Base Station B Mobile Terminal M Forward Channel Reverse Channel Forward Channel and Reverse Channel use different frequency bands

Access Methods FDMA TDMA CDMA Frequency Frequency Time Time Frequency

Clusters A cluster is a group of cells No channels are reused within a cluster A seven Cell Cluster

Example - Frequency Spectrum Allocation in U.S. Cellular Radio Service Reverse Channel Forward Channel 991 992 … 1023 1 2 … 799 991 992 … 1023 1 2 … 799 824-849 MHz 869-894 MHz Channel Number Center Frequency (MHz) Reverse Channel 1 <=N <= 799 991 <= N <= 1023 0.030N + 825.0 0.030(N-1023) + 825.0 Forward Channel 1 <=N <= 799 991 <= N <= 1023 0.030N + 870.0 0.030(N-1023) + 870.0 (Channels 800-990 are unused) Channel bandwidth is 45 MHz

Frequency Reuse Only a small number of radio channel frequencies were available for mobile systems Therefore engineers had to find a way to reuse radio channels to carry more than one conversation at a time The solution the industry adopted was called frequency reuse. Implemented by restructuring the mobile telephone system architecture into the cellular concept

Frequency Reuse The concept of frequency reuse is based on assigning to each cell a group of radio channels used within a small geographic area Cells are assigned a group of channels that is completely different from neighbouring cells The coverage area of cells is called the footprint and is limited by a boundary so that the same group of channels can be used in cells that are far enough apart

Frequency Reuse Cells with the same number have the same set of frequencies Frequency Reuse

Frequency Reuse using 7 frequencies allocations Each cell is generally 4 to 8 miles in diameter with a lower limit around 2 miles.

Cell Splitting Allows urban centres to be split into as many areas as necessary for acceptable service levels in heavy-traffic regions, while larger, less expensive cells can be used to cover remote rural regions

Cellular Concept with Sectors frequency re-use base station

Hand-off The final obstacle in the development of the cellular network involved the problem created when a mobile subscriber moved from one cell to another during a call

GSM infrastructure MSC, BSC, BTS, VLR, HLR, GSGN, GSSN

Compared to a fixed network Gateway MSC Transit exchang Local switches MSC BSC Subscriber stage Fixed phone MS

What’s new? Radio access network Encryption Voice coding Locate a mobile station Identify and authenticate Handle mobility during a call

A bird eye’s view GMSC Access Network MSC databases BTS BSC BSC BSC

”Typical” Mobile operator One to ten MSC per 1 M subscribers Ten to one hundred BSC per MSC Thousands of BTS per 1 M subscribers

Base Transceiver Station Controls the radio link encryption error control signal strength 1 - 6 duplex carriers, for example: two layers 120o sectors (6+8)*3 = 42 voice calls Cost ~ 100 – 200 k$

Base Station Controller communication with the mobile terminal local hand-over voice codecs carrier allocation paging to terminals talks to the MSC serves up to 40 BTSs could be co-located with MSC

Mobile Switching Centre Mobility management identifies and authenticates locates switches between BSCs Handover to other MSCs 64 kbps regular voice channels

Radio Access network A carrier is divided into logical channels control channels CCH traffic channels TCH The first carrier holds 2 controll channels and 6 traffic channels. Additional carriers holds only traffic channels.

Control Channels Broadcast Common control Dedicated control Frequency correction: to synchronize (FCCH) Broadcast control: this is me, these are my neighbours (BCCH) Common control Paging: to notify a mobile station (PCH) Random access: for the mobile to request service (RACH) Access grant: reply with assigned dedicated control channel (AGCH) Dedicated control Standalone dedicated control: used during call set-up, SMS etc (SDCCH) Slow associated control: power, time etc (SACCH) Fast associated control: handover etc, uses the TCH (FACCH) Cell broadcast: cell broadcast

Traffic Channels Duplex Error control Full rate (TCH/F) Forward Error Correction (FEC) retransmission (ARQ) Full rate (TCH/F) 13 Kbps speech 9,6 or 14,4 Kpbs data Half rate (TCH/H) 6,5 Kbps speech 7,2 or 4,8 Kbps data

Logical channels Hyperframe: 2048 superframes 3h28m Superframe: 26 or 51 multiframes 6.12 s CCH CCH Multiframe: 26 or 51 TDMA frames CCH TCH 8 time-slot TDMA frame 4.143 ms

One TDMA frame Normal burst Frequency correction burst 148 b 0.577 ms tail guard 8.25 tail training Normal burst 3 57 b 26 b 57 b 3 user data user data stealing flags Frequency correction burst Synchronization burst Dummy burst Access burst

Keeping track of a mobile station VLR visiting location register Location area Location area update the VLR with new location area

Moving to a new MSC VLR which LA which MSC ? Location area update the VLR with new location area and new MSC

but also…. HLR home location register VLR update the home location register!

Home Location Register incomming call PSTN where is the mobile? GMSC HLR MSC How do we reach him? VLR

Mobile station numbers mobile subscriber ISDN number (MSISDN) i.e. the phone number PSTN GMSC HLR Mobile Station Roaming Number (MSRN). MSC VLR Temporary Mobile Subscriber Identity International Mobile Subscriber Identity

GPRS Internet Gateway GPRS Support Node GGSN Packet Control Unit Access Network Packet Control Unit BTS BSC UDP/TCP tunnel Serving GPRS Support Node SGSN BTS MS BTS

Looking to PCS from different Angles Internet PSTN (Telephone Network) Wireless Access Mobile Users Laptop users Pocket PC users Mobile IP, DHCP enabled computers Mobile Users Cell phone users Cordless phone users Telecom People View Data Networking People View

Telecom and Data Networking Telecom Interest Data Networking Interest - Voice Transmission - Frequency Reuse Handoff Management Location Tracking Roaming QoS GSM, CDMA, Cordless Phones, GPRS, EDGE Data Transmission Mobile IP (integrating mobile hosts to internet) Ad-hoc Networks TCP over Wireless Service Discovery Radio Propagation Link Characteristics Error Models -Wireless Medium Access (MAC) - Error Control

Major Mobile Radio Standards - Europe Type Year Intro Multiple Access Frequency Band (MHz) Modulation Channel BW (KHz) ETACS Cellular 1985 FDMA 900 FM 25 NMT-900 1986 890-960 12.5 GSM Cellular/PCS 1990 TDMA GMSK 200KHz C-450 450-465 20-10 ERMES Paging 1993 FDMA4 Several 4-FSK CT2 Cordless 1989 864-868 GFSK 100 DECT 1880-1900 1728 DCS-1800 Cordless/PCS 1710-1880 200

Example - Frequency Spectrum Allocation in U.S. Cellular Radio Service Reverse Channel Forward Channel 991 992 … 1023 1 2 … 799 991 992 … 1023 1 2 … 799 824-849 MHz 869-894 MHz Channel Number Center Frequency (MHz) Reverse Channel 1 <=N <= 799 991 <= N <= 1023 0.030N + 825.0 0.030(N-1023) + 825.0 Forward Channel 1 <=N <= 799 991 <= N <= 1023 0.030N + 870.0 0.030(N-1023) + 870.0 (Channels 800-990 are unused) Channel bandwidth is 45 MHz

2G Technologies cdmaOne (IS-95) GSM, DCS-1900 IS-54/IS-136 PDC Uplink Frequencies (MHz) 824-849 (Cellular) 1850-1910 (US PCS) 890-915 MHz (Eurpe) 1850-1910 (US PCS) 800 MHz, 1500 Mhz (Japan) Downlink Frequencies 869-894 MHz (US Cellular) 1930-1990 MHz (US PCS) 935-960 (Europa) 1930-1990 (US PCS) 869-894 MHz (Cellular) 1930-1990 (US PCS) 800 MHz, 1500 MHz (Japan) Deplexing FDD Multiple Access CDMA TDMA Modulation BPSK with Quadrature Spreading GMSK with BT=0.3 p/4 DQPSK Carrier Seperation 1.25 MHz 200 KHz 30 KHz (IS-136) (25 KHz PDC) Channel Data Rate 1.2288 Mchips/sec 270.833 Kbps 48.6 Kbps (IS-136) 42 Kbps (PDC) Voice Channels per carrier 64 8 3 Speech Coding CELP at 13Kbps EVRC at 8Kbps RPE-LTP at 13 Kbps VSELP at 7.95 Kbps

GSM Speech Signal Processing

GSM and CDMA Coverage Map Worldwide

Evolution

1G TECHNOLOGY 1G refers to the first generation of wireless telephone technology, mobile telecommunications which was first introduced in 1980s and completed in early 1990s. It's Speed was upto 2.4kbps. It allows the voice calls in 1 country. 1G network use Analog Signal. AMPS was first launched in USA in 1G mobile systems. 43 43

Poor Handoff Reliability DRAWBACKS OF 1G Poor Voice Quality Poor Battery Life Large Phone Size No Security Limited Capacity Poor Handoff Reliability 1G Wireless System 44 44

2G TECHNOLOGY 2G technology refers to the 2nd generation which is based on GSM. It was launched in Finland in the year 1991. 2G network use digital signals. It’s data speed was upto 64kbps. Features Includes: It enables services such as text messages, picture messages and MMS (multi media message). It provides better quality and capacity . 45

2G requires strong digital signals DRAWBACKS OF 2G 2G requires strong digital signals to help mobile phones work. If there is no network coverage in any specific area , digital signals would weak. These systems are unable to handle complex data such as Videos. 2G Wireless System 46 46

3G TECHNOLOGY 3G technology refer to third generation which was introduced in year 2000s. Data Transmission speed increased from 144kbps- 2Mbps. Typically called Smart Phones and features increased its bandwidth and data transfer rates to accommodate web-based applications and audio and video files. 47

FEATURES OF 3G TECHNOLOGY Providing Faster Communication Send/Receive Large Email Messages High Speed Web / More Security Video Conferencing / 3D Gaming TV Streaming/ Mobile TV/ Phone Calls Large Capacities and Broadband Capabilities 11 sec – 1.5 min. time to download a 3 min Mp3 song. 48

DRAWBACKS OF 3G TECHNOLOGY Expensive fees for 3G Licenses Services It was challenge to build the infrastructure for 3G High Bandwidth Requirement Expensive 3G Phones. Large Cell Phones 49

4G TECHNOLOGY (Anytime ,Anywhere) 50

4G TECHNOLOGY (Anytime ,Anywhere) 4G technology refer to or short name of fourth Generation which was started from late 2000s. Capable of providing 100Mbps – 1Gbps speed. One of the basic term used to describe 4G is MAGIC. MAGIC: Mobile Multimedia Anytime Anywhere Global Mobility Support Integrated Wireless Solution Customized Personal Services Also known as Mobile Broadband Everywhere. 51

Countries Have 4-G Except for the Scandinavian Countries (Northern Europe that includes Denmark and two of the nations of Scandinavian , Norway and Sweden. ), a few countries have started the 4G commercially. In the US, Sprint Nextel and Others Germany , Spain, China , Japan and England are also using the 4G services and mobiles . 52

WIRLESS MODELS OF 3G & 4G 3G WIRELESS SYSTEM 4G WIRELESS SYSTEM 53 53

5G TECHNOLOGY 5G technology refer to short name of fifth Generation which was started from late 2010s. Complete wireless communication with almost no limitations. It is highly supportable to WWWW (Wireless World Wide Web). 54

BENEFITS OF 5G TECHNOLOGY High Speed, High Capacity 5G technology providing large broadcasting of data in Gbps . Multi - Media Newspapers, watch T.V programs with the clarity as to that of an HD Quality. Faster data transmission that of the previous generations. Large Phone Memory, Dialing Speed, clarity in Audio/Video. Support interactive multimedia , voice, streaming video, Internet and other 5G is More Effective and More Attractive. 55

EVOLUTION OF 1G TO 5G TECHNOLOGY 56

WIRELESS APPLICATIONS Wireless applications are those which we use free space as the transmission medium & do not involve cabling like fibre or copper cables. 57

Wireless solution for: Business and Industry Schools , Colleges WIRELESS SERVICES Wireless solution for: Business and Industry Schools , Colleges Doctors , Pilots Police and Vehicles etc. 58

CONCLUSION All totally the best way to help all users is to use 5G as the next wireless system and in totally it is safety and secure for public, this the need that demands the solution. Today’s wired society is going wireless and if it has problem, 5G is answer. 5G technology is going to give tough competition to Computers and Laptops. It will be available in the market 2020 at affordable cost with more reliability than previous mobiles. 59 59