Dr. Shahriar Bijani Shahed University Spring 2016 Communication Security Lecture 3: Introduction to Cellular Mobile Networks Dr. Shahriar Bijani Shahed University Spring 2016

Main References A. S. Tanenbaum and D. J. Wetherall, Computer Networks (5th Edition), Pearson Education, the book slides, 2011. Patrick Traynor, CS 8803 - Cellular and Mobile Network Security, Georgia Tech Information Security Center, 2012. General Packet Radio Service (GPRS) For Engineers, Aircom International.

Outline Circuit Switching vs. Packet Switching Multiplexing Mobile Phone Standards Figures

Circuit Switching CIRCUIT CIRCUIT SWITCH SWITCH CIRCUIT SWITCH CIRCUIT

Packet Switching 1 2 3 5 4 1 2 3 4 5 PACKET PACKET SWITCH ASSEMBLER/ DISASSEMBLER PACKET SWITCH

Packet Switching 1 2 3 5 4 1 2 3 4 5 PACKET PACKET SWITCH ASSEMBLER/ DISASSEMBLER PACKET SWITCH 1 2 3

Packet Switching 1 2 3 5 4 1 2 3 4 5 PACKET PACKET SWITCH ASSEMBLER/ DISASSEMBLER PACKET SWITCH 1 2 3

Packet Switching 1 2 3 5 4 1 2 3 4 5 PACKET PACKET SWITCH ASSEMBLER/ DISASSEMBLER PACKET SWITCH 1 2 3

Packet Switching 1 2 3 5 4 1 2 3 4 5 PACKET PACKET SWITCH ASSEMBLER/ DISASSEMBLER PACKET SWITCH 2 1 3

Packet Switching 1 2 3 5 4 1 2 3 4 5 PACKET PACKET SWITCH ASSEMBLER/ DISASSEMBLER PACKET SWITCH PACKET SWITCH 2 3 1 PACKET SWITCH 2 3 1 PACKET SWITCH PACKET SWITCH

Packet Switching 1 2 3 5 4 1 2 3 4 5 PACKET PACKET SWITCH ASSEMBLER/ DISASSEMBLER 1 2 3 PACKET SWITCH PACKET SWITCH 1 2 3 2 1 3 2 3 1 PACKET SWITCH 1 2 3 2 3 1 PACKET SWITCH PACKET SWITCH

Advantages of Packet Switching More efficient use of existing carriers More suited to bursty-type traffic such as Internet access. Compatibility with existing packet-switched networks (PSNs) such as the Internet

Advantages of Circuit Switching More suited to time-sensitive applications No contention for network resources Less data overheads for routing requirements Compatibility with existing circuit-switched networks (eg PSTN/ISDN)

Packet Routing Strategies Connection-Orientated (CONS): Packet route established prior to data transfer Supports flow control Supports QoS functions Connectionless (CNLS) No predefined route - packets routed individually No guarantee of delivery Difficult to implement QoS

Packet Data Delivery Acknowledged Mode: Unacknowledged Mode Guarantees error-free delivery Supports flow control Requires additional overheads Lower data throughput Unacknowledged Mode Packets are delivered to the network and forgotten No indication of delivery or error correction Generally relies on higher layer protocols for error detection and correction More efficient in reliable networks

Packet Switching Technologies X.25 Frame Relay ATM

The Virtual Circuit (VC) Concept 1 2 3 PACKET SWITCH PACKET SWITCH 1 2 3 2 1 3 2 3 1 PACKET SWITCH 1 2 3 2 3 1 PACKET SWITCH PACKET SWITCH Virtual Circuit

Virtual Circuit Connections Permanent Virtual Circuit (PVC): Established by NMC Dedicated resource for specific user Connectionless Switched Virtual Circuit (SVC): Setup on request Temporary allocation of resources Cleared on completion of session

Outline Circuit Switching vs. Packet Switching Multiplexing Mobile Phone Standards Figures

Modulation & Multiplexing Modulation: To send digital information, we must change analog signals to represent bits. includes: sampling quantizing Encoding Example: PCM (Pulse Code Modulation) the simplest form of speech coding 2 standards: A-law in Europe (24-channels), and µ-law in the USA (30/32 channels). Multiplexing: sharing one channel by multiple signals Using a single channel (wire) to carry several signals is better than to allocate a channel (install a wire!) for every signal. PCM Reference: http://www.technologyuk.net/telecommunications/telecom_principles/pulse_code_modulation.shtml

Multiplexing Different multiplexing methods: Frequency Division Multiplexing (FDM) Time Division Multiplexing (TDM) Code Division Multiplexing (CDM) Beam Division Multiplexing (BDM)

Frequency Division Multiplexing (FDM) AKA: Frequency Division Multiple Access (FDMA) FDM: divides the spectrum into frequency bands each user having exclusive ownership of some band to send their signal. E.g.: AM radio. The allocated spectrum is about 1 MHz (~ 500 to ~1500 kHz) Different frequencies are allocated to different logical channels (stations) AM radio uses amplitude modulation vs FM (frequency modulation) radio

Frequency Division Multiplexing (FDM) (a) The original bandwidths. (b) The bandwidths raised in frequency. (c) The multiplexed channel.

Frequency Division Multiplexing Orthogonal frequency division multiplexing (OFDM).

Time Division Multiplexing (TDM) AKA: Time Division Multiple Access (TDMA) TDM is used widely as part of the telephone and cellular networks. TDM is different from STDM. STDM (Statistical Time Division Multiplexing): Channel is allocated according to the statistics of each stream’s demand STDM is packet switching.

Code Division Multiple Access (CDM) AKA: Code Division Multiple Access (CDMA) Narrowband signal is spread over a wider frequency band. Advantages: More tolerant of interference, Allowing multiple signals from different users to share the same frequency band.

Beam Division Multiple Access (BDM) AKA: Beam Division Multiple Access (BDMA) New access technique for 5th generation of mobile wireless communication. The base station allocates separate antenna beams to each of the mobile devices. Based on position and moving speed, base station will calculate both width and direction of the beam for all the mobile stations. BDMA helps in achieving higher system capacity.

Multiple-Access Radio Techniques Courtesy of Petri Possi, UMTS World

CDMA Courtesy of Suresh Goyal & Rich Howard

CDMA Courtesy of Suresh Goyal & Rich Howard

CDMA Courtesy of Suresh Goyal & Rich Howard

CDMA Courtesy of Suresh Goyal & Rich Howard

Code Division Multiplexing (1) Chip sequences for four stations. Signals the sequences represent

Code Division Multiplexing (2) Six examples of transmissions. Recovery of station C’s

Analog vs. Digital Telephone Systems Analog/ Digital telephone systems: Analog is the translation of voice into electrical impulses (pure waveform). Cheap Low bandwidth (limited data communication). Noise Digital is an approximation of the waveform, represented in 0s and 1s Expensive High bandwidth Better voice (less noise)

Wireless Internet vs. Cellular Net The Internet - Wireless Networks Classic Cellular Telecommunications Networks Designed for voice, not for Internet access

Outline Circuit Switching vs. Packet Switching Multiplexing Mobile Phone Standards Figures

Upgrade paths from 2G Technologies to 3G IS-95 IS-136 & PDC GSM- EDGE GPRS HSCSD IS-95B Cdma2000-1xRTT Cdma2000-1xEV,DV,DO Cdma2000-3xRTT W-CDMA TD-SCDMA 2G 3G 2.5G 3GPP 3GPP2 Source: ICIL

Mobile Phone Standards

A Comparison of All Mobile Generations Technology Features 1G 2G 3G 4G 5G Start/ Deployment 1970 / 1984 1980 / 1999 1990 / 2002 2000/ 2010 2020 Data Bandwidth 2kbps 64kbps 2Mbps 200Mbs/ 1 Gbps 1 Gbps + Standard TACS, AMPS (Analog Cellular Technology) TDMA, CDMA, GSM, GPRS, EDGE (Digital) WCDMA, CDMA-2000, HSPA WiMax , LTE, Wi-Fi Unified IP & seamless combination of broadband , LAN, WAN, PAN,WLAN & www Service Mobile Telephony (Voice) Digital voice, SMS, Higher capacity packetized data Integrated high quality audio, video and data Dynamic Information access, Wearable devices Dynamic Information access, Wearable devices with AI capabilities Multiplexing FDMA TDMA, CDMA CDMA CDMA, BDMA Switching Circuit Circuit, Packet (Circuit,) Packet All Packet Core Network PSTN Packet Network Internet Handoff Horizontal Horizontal and Vertical BDMA: Beam-Division Multiple Access

GSM / 3GPP Releases GSM Phases 3GPP Releases GSM Phase 1 1992   3GPP Releases GSM Release Start Date GSM Phase 1  1992 GSM Phase 2  1994 GSM Phase 2+  1997 GSM Phase 2+ Release 97  1998 GSM Phase 2+ Release 98  1999 GSM Phase 2+ Release 99 (3GPP UMTS Release 99) 2000 Release Start Date Release 4 (all IP) 2001 … Release 7 2007-8 Release 8 (LTE)  2008-9 Release 8 (LTE Advanced)   Release 13 2016 Release 14 2017

Mobile Networks’ Figures Compound Annual Growth Rate

Compound Annual Growth Rate Mobile Usage Source: Ericsson, Nov. 2015

Total number of mobile subscribers in Q3 2015: ~7.3 billion 87 million new subscribers Source: Ericsson, Nov. 2015

average 1.7% of Android smartphone users upgraded to a new Android smartphone

Wi-Fi traffic is not included. Average data consumption increases between 20% and 45% per subscription after smartphone model upgrades

Iran’s Figures Q4 2015 Connections: 113.9M 4.90% (annual growth) Source: GSMA Intelligence 2016 Q4 2015 Connections: 113.9M  4.90% (annual growth) Prepaid 71%  -1.07% mobile broadband (includes 3g & 4G) 14%  2,125% Population 79.6M 1.21% SIM penetration 143%  3.66%