1. ESE505
Wireless Communications
Xin Wang (xwang@ece.sunysb.edu)
Office: 235 Light Engineering building
Meeting time: 4:45pm – 7:35 pm, Tu
Office Hour: Tue:2:40 -4:40 pm; Tue: 7:40 pm- (By
appointment)
2. Course Overview
Overview of wireless techniques
Characteristics of the mobile radio environment–
propagation phenomena
Cellular concept and channel allocation
Dynamic channel allocation and power control
Modulation techniques (including OFDM used in 4G and 5G)
Multiple access techniques: FDMA, TDMA, CDMA; system
capacity comparisons
Coding for error detection and correction
Second-generation, digital, wireless systems
Performance analysis: admission control and handoffs
2.5G/3G mobile wireless systems: packet switched data
4G/5G mobile wireless systems
Access and scheduling techniques in cellular systems
3. References
Textbook:
– Mischa Schwartz, Mobile Wireless Communications, Cambridge
University Press, 2005.
Reference books
– Theodore Rappaport, Wireless Communications, Principles and
Practice, Second Edition, Prentice Hall, 2002.
– Andrea Goldsmith, Wireless Communications, Cambridge University
Press, 2005.
– Vijay K. Garg, Wireless Network Evolution: 2G to 3G, Prentice Hall,
2001.
– John G. Proakis, Digital Communications, 4th ed., Boston : McGraw-
Hill, c2001.
– David Tse, Pramod Viswanath, Fundamentals of Wireless
Communications, Cambridge University Press, 2005. (Advanced. If
you want to learn antenna and MIMO techniques)
Lecture notes: Posted on blackboard.
Caution: lectures go fast with slides, so please ask questions or ask
for a pause
4. Projects
Single or in group (not exceeding 3 students).
Thoroughly search and read papers on a selected
topic, and write a survey paper.
Delivery:
– Final report on the surveyed topic, in technical report format.
7. Mobile Communications Today: Tale of 2 Networks
Cellular Telecommunications Networks
– Conventionally tailored for voice: very low bandwidth
– Conventional phones not targeting for Internet and computing applications
– Smart phones: with data going through Internet
– 2G, 3G, 4G, 5G …
Despite high penetration, data bandwidth is still limited
Wireless Enterprise Networks
–Tailored for best-effort data traffic: high bandwidth, no controls
–Supports general computing and data networking applications
–e.g, WiFi
Edge
Router
Telephone
Network
Internet
Base
Station
Telephone
Network
Internet
Wireless
Gateways
Wireless
Controllers
Access
Router
Base
Station /
Access
Point
8. … Tomorrow – Common Net, Common Apps
Core Internet
Backbone
Authentication
Presence
Location
Aggregation
Router
Aggregation
Router
Aggregation
Router
Access
Router
Access
Router
3G Cellular
Networks
Radio
Controller Access
Router
Urban
Networks
Home
Networks
Enterprise
Networks
4G
Radios
Ad Hoc
Networks
4G Air
Interface
4G
Radios
• DSL/Cable
• High Speed
Internet Access
•Wireless mesh
•WiMAX
• Broadband
Distribution
Networks
• High Speed
Pico Cells
•Fixed Wireless
• 802.11++
(802.11n,ac,ad)
• Local Mobility
• Packet Voice
• High Data
Rates
• Outdoor Areas
• High Mobility
• Allow People to
network
• Self Configuring
• End-to-end Internet
– common mobility management & control
– common transport infrastructure
– common services infrastructure
Unifies access technologies
(wireless and wireline)
• MIMO
• Small cells
(Femtocell)
• D2D
• Hybrid
5G
• 1000x capacity
•Extremely low latency and
high reliability
(mmWave, massive MIMO)
Killer apps: autonomous vehicl
Virtual reality
9. Overview of Traditional Wireless Networks
Primarily wireless access to wired networks
New features compared to wired networks
– wireless media
– mobility
New features = New Problems (or new
challenges!)
11. Mobility
Mobility types:
– personal mobility: ability of the user to access personalized
network services where away from home network
through intelligent end-to-end location aware layer
– terminal mobility: ability of the network to maintain continuous
service when user’s terminal changes locations
Challenges: QoS, multi-home devices
– Network mobility: roaming of the entire sub-network
Move at high speeds while communicating
– cellular voice
Travel large distances between communication
– cellular
– messaging/paging
Limited Mobility
– wireless LANs
– fixed wireless/wireless local loops
12. Coverage Area
Pico-cell – O(10m)
– covers a room
Micro-cell – O(100m)
– covers a floor/street
Macro-cell – O(10 mi.)
– big towers
Satellites
– regions/countries
13. Mobility Terminology
Mobile Location
– finding a mobile to deliver a connection/packet
– usually requires finding the cell in which a user is located
Mobile Tracking
– following the approximate location of a mobile as it moves
while not in an active session
– usually involves some sort of registration
Tradeoff between mobile location and tracking …
Handoff (Handover)
– transferring/forwarding a connection as a user moves
across cells while in an active session
14. U.S. Frequency allocation
940 0.5 9 15
941 0.5 9 15
1,850 0.5 10 15
2,200 0.5 10 15
2,500 0.5 11 15
6,000 0.5 12 15
0
1
10 100 1,000 10,000 100,000
Established
Transition
Emerging
Cordless
Wireless
CATV
Microwave
Wireless
LAN, PBX
Mobile
Satellite
Internet &
Mobile
Computing
Global Coverage Consumer Broadband
Intelligent Network
PCS
Cellular
Paging
Fixed
Wireless
Rapid Deployment
Private to Public One-Way to Two-Way
SMR
FM
TV TV Satellite
AM Radio Long-Haul Sat
Short-Haul
Military & Exploratory
U. S. Spectrum Allocation (Freq. in MHz)
15. Frequency Band Usage
Frequency Range Example Usage
300Hz – 3000Hz Analog telephone
300kHz to 3MHz AM Radio
3 to 30MHz Amateur Radio, international broadcasting
(BBC, VoA)
30 to 300MHz VHF television, FM Radio
300 to 3000MHz UHF television, cellular telephone, PCS
3 to 30GHz Satellite communication, radar, wireless local
loop
30 to 300GHz Experimental; WLL; Millimeter Wave
300GHz to 400THz Infrared LAN, consumer electronics
400 to 900 THz Optical communication
16. Frequency Bands Usage Example
Frequency Range (MHz) Example Usage
824-849, 869-894 AMPS
NA-TDMA/IS-136
CDMA/IS-95
CDMA2000 3G1x
902-928, 2400-2484
5150-5350, 5725-5825
ISM (Industrial Scientific
Medical) , unlicensed
890-915, 935-960 GSM
1710-1785, 1805-1885 3G
1850-1910,1930-1990 3G
2300, 2500, 5200, 5700 4 G
17. Challenges in Wireless Communications
Harsh environment
– continuously changing characteristics: adaptation
– high error rate: FEC-based channel coding
– bursty errors due to sudden fades: interleaving
– higher layer error recovery
Mobility
– signal strength varies with location
– motion affects signals
– must “change” channels during handoffs
18. Categories of Noise
Thermal Noise
– Due to agitation of electrons
– Present in all electronic devices and transmission media
– Cannot be eliminated
– Function of temperature
Inter-modulation noise
– Interference caused by a signal produced at a frequency that
is the sum or difference of original frequencies
– In a transmission path or device, noise, generated during
modulation and demodulation, that results from nonlinear
characteristics in the path or device.
Crosstalk
Impulse Noise
– Irregular pulses or noise spikes
– Short duration and of relatively high amplitude
19. Signal-to-Noise Ratio
Ratio of the power in a signal to the power contained in
the noise that’s present at a particular point in the
transmission
Typically measured at a receiver
Signal-to-noise ratio (SNR, or S/N)
A high SNR means a high-quality signal, low number of
required intermediate repeaters
SNR sets upper bound on achievable data rate
power
noise
power
signal
log
10
)
(
power
noise
power
signal
10
dB
SNR
SNR
20. Expression Eb/N0
Similar to SNR but does not depend on bandwidth
Ratio of signal energy per bit to noise power density per
Hertz
The bit error rate for digital data is a decreasing
function of Eb/N0
– Given a value for Eb/N0 to achieve a desired error rate,
parameters of this formula can be selected
– As bit rate R increases, transmitted signal power must increase
to maintain required Eb/N0
R
B
N
S
B
N
R
S
N
Eb
/
/
0
21. Limits of wireless channel
Shannon defined the capacity limits of communication
channel with additive white Gaussian noise (AWGN)
For a channel without fading, shadowing, ISI, the
maximum possible data rate on a given channel of
bandwidth B is
R = B log2(1+SNR) bps
where SNR is received Signal to Noise Ratio
This theoretical limit cannot be achieved in practice
but novel design and coding techniques help data rates
approach this bound
22. Summary
Wireless
– harsh media
– high error rates, limited spectrum, etc.
Mobility
– limited battery power
– impacts all protocol layers (physical layer to application layer)
Solutions
– Key is uncertainty management (mobility, environment)
– Requires enhancements in each layer
Physical – coding/interleaving/modulation/…
MAC – TDMA/CDMA/…
Network/Transport/Applications – Adapt to wireless and mobility
– Must be robust to unexpected events such as disconnection etc.
– Scalable to billions of users
25. Outline
Evolution: 1G, 2G, 3G, 4G, 5G …
Wireless access
– FDMA (AMPS: Advanced Mobile Phone System)
– TDMA (IS-54, IS-136, GSM: Global System for Mobile)
– CDMA (IS-95, CDMA2000, UMTS: Universal Mobile Telecomm.
System)
–-OFDM (WiMAX, LTE)
Network
–Connection oriented networks for voice
Public Switched Telephone Network (PSTN)
–Packet overlay networks for data
General Packet Radio Service (GPRS) – GSM and UMTS
Enhanced Version Data Only (EVDO) – CDMA
Signaling protocols
– Air interfaces signaling is specific to the standard
– Signaling system no. 7 for voice and GPRS
– IETF protocols for EVDO
27. First Generation Analog System
First Generation
– Advanced Mobile Phone System/Service
(AMPS)
– Provides analog traffic channels
– Developed by AT&T in 1970s
– Early deployment in 1980s
– Greater than 40 million users in 1997
28. Going Beyond First Generation
Capacity
– Increase capacity by operating with smaller cells,
adding spectrum, and/or use new technology to
improve spectrum efficiency
Roaming
– Requires information transfer and business
arrangement between systems
– Introduce IS-41
Security
– AMPS authentication procedures are weak
– Introduce robust network security technology
based on encryption and secure key distribution
Support for non-voice services
29. Second Generation System
Introduced in the early 1990s
Digital traffic channel instead of analog
Since data and control traffic are sent in digital
form:
– Encryption of traffic is simple
– Error detection and corrections can be applied, voice
reception quality can be better
– Multiple channels per cell, as well as multiple users per
channel (through TDMA or CDMA)
30. Third Generation Systems
Provides high-speed wireless communication
for multimedia
– Voice: quality comparable to PSTN
– Data: 144kpbs for high-speed user (driving),
384kpbs for slowly moving user (walking) and
2.048Mbps for stationary user in one sector
Primarily CDMA-based
– CDMA 2000 in US
– UMTS in Europe
2.5G Systems
– GPRS (GSM)
31. Fourth Generation Systems
Further increase communication speed,
particularly for mobile users
– Data: 100Mbps for high-speed user (driving),
1Gbps for slowly moving user (walking)
Primarily OFDM-based
– Also add smart antenna, MIMO
32. Fifth Generation Systems
Connect virtually everyone and everything together,
including machines, objects, and devices.
Provide high speeds, superior reliability and negligible
latency
Provide an unified, more capable air interface, with an
extended capacity to enable next-generation user
experiences, new deployment models and new services.
– Enhanced mobile broadband
Support new immersive experiences: VR and AR with faster, more uniform
data rates, lower latency, and lower cost-per-bit.
– Mission-critical communications
Enable new services that can transform industries with ultra-reliable,
available, low-latency links like remote control of critical infrastructure,
vehicles, and medical procedures.
– Massive IoT
Seamlessly connect a massive number of embedded sensors in virtually
everything by scaling down in data rates, power, and mobility—providing
extremely lean and low-cost connectivity solutions.
33. 3G/ IMT-2000 Capable
Existing Spectrum New Spectrum
IS-95-A/
cdmaOne
IS-95-B/
cdmaOne
IS-136
TDMA
136 HS
EDGE
GSM
GSM GPRS EDGE
WCDMA
(>5MHz)
cdma2000 1X (1.25 MHz)
cdma2000 3X (3.75-5 MHz)
HSCSD
1XEV DO: HDR (1.25 MHz)
2G “2.5G”
Wireless Standards Evolution to 3G
1G
Analog
AMPS
TACS
TACS: Total Access Telecomm. Sys.
HSCSD: High Speed Circuit Switched Data EDGE: Enhanced Data rates for GSM Evolution
34. Reference Architecture
MS BTS BSC MSC
MSC PSTN/ISDN
VLR VLR
HLR AC
Wireless Network
MSC HLR
MS: mobile subscriber, with IMSI
BTS: base terminal station
BSC: base station controller
MSC: mobile switching center
HLR: home location register
AC: authentication center
VLR: visitor’s location register
IMSI: International Mobile Subscriber Identity
35. Network Architecture: Key Components
Mobile Station – user handset
Base Terminal Station – terminate the air interface
Base Station Control – manage a set of BTSs, handle
handoff within BSC and reduce load of MSC.
Mobile Switching Center – central intelligence, manage
mobility, provides services
Home Location Register – store permanent service
profile for subscribers, points to current VLR
Visitor Location Register – store temporary service
profile for a roaming subscriber, current location
MS BTS BSC MSC
VLR
HLR
36. Voice path
MS BTS BSC MSC
VLR
HLR
Coded voice (GSM: 13.4 kbps)
Full rate voice (64 Kbps)
PSTN/ISDN
37. Basic Network Architecture
MS BS
Serving
MSC
MSC
Network
VLR VLR
Gateway
MSC
HLR
MSC
BS
BS
BS
• Gateway MSC receives incoming calls for mobiles
- if using a home MSC, it is permanently assigned
• Serving MSC: assigned based on location of mobile subscriber
• HLR: permanent registry for service profiles, pointer to VLR
• VLR: temporary repository for profile information, pointer to serving MSC
38. Network Architecture: UMTS/GPRS/GSM
• RNC
– Radio network controller
manages a set of basestations
(Node B)
• HLR
– uses the GSM MAP protocol
for location management
and authentication
• MSC/GMSC
– call control and mobility
management for circuit
switched (CS) users
• SGSN/GGSN
– uses GPRS Tunneling Protocol
(GTP) to provide mobility
management and transport for
packet switched (PS) users
Internet
MSC
SGSN
GGSN
GMSC
HLR
PSTN
VLR
PSTN
IuPS
Figure based on
UMTS TS-23.002
Firewall +
IP Router
IuCS IuPS
MS
IuPS
A
RNC
Um
BSC
BTS
BTS
RNC
Node BNode B
Um
BSC
BTS
BTS
Uu
Uu
2G CS 2.5G
PS
MS
BTS
GTP
Voice
Path
Data
Path
39. Network Architecture: CDMA, CDMA2000
Data path
RNC/PCF
– performs frame-selection/power
control
– terminates Radio Link Protocol
(RLP) with mobiles and performs
packet and burst control functions
PDSN (Packet Data Serving Node)
– terminates Point-to-Point Protocol
– provides foreign agent (FA)
support for Mobile IP enabled
clients
AAA - provides Authentication,
Authorization, and Accounting for
data users
Voice path
BSC
– Coordinates handoff for voice users
– performs frame-selection/power
control
MSC
– call control and mobility management
– interfaces to the PSTN for voice
users
HLR
– provides location management and
AAA functions for voice users using
the IS41 protocol
BS
RNC/PCF
SS7
Internet
PSTN
PDSN
FA
HA
MSC
VLR
CDMA
R-P if
IP
HLR
AAA
BS
Soft
handoff
42. Cellular Services
Automatic call delivery
– find a user, deliver a call
IN-type services
– e.g., call forwarding
Messaging
– short message service
Connection oriented user data transfer
– voice, fax, circuit-switched data
Packet data
– Enhanced Version Data Only (EVDO) for CDMA systems
– General Packet Radio Service (GPRS) for GSM/UMTS
system
43. High Level Call Flow
Mobile user registration
– power up/down
– movement
– periodic
Call recipient location
– call routed to gateway or home MSC
– gateway MSC searches for called mobile (via HLRs and
VLRs)
– mobile user is paged (determines current base station)
Call delivering
– uses standard SS7 procedures
44. Basic Network Architecture
MS BS
Serving
MSC
MSC
Network
VLR VLR
Gateway
MSC
HLR
MSC
BS
BS
BS
• Gateway MSC
- receives incoming call
- queries HLR to find mobile station
• HLR
- queries VLR to find mobile station
• Serving MSC
- pages mobile station
45. Mobile Registration – High Level
Old Serving
MSC
Old
VLR
HLR VLR MSC BS MS
Update
Location
Cancel
Location
Authenticate
46. Mobile Call Delivery – High Level
Gateway
MSC
HLR VLR MSC BS MS
Call
request
Request
Routing
Info
Routing
Number
Call
request
Page
Connect
SS7 Call Delivery
47. Hierarchy of Location Information
HLR
VLR
VLR
MSC
MSC
MSC
G-MSC
Phone
number
Registration
Registration
paging
