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Fourth Generation (4G)Wireless Systems
Jeremy Mayeres
Topics
Cellphones 1G 2G 3G 4G/IMT-Advanced LTE WiMAX 4G Today Future of 4G Social/Ethical considerations
Cellphones
Radio telephony existed long before cell phones became popular
1947 – Ring and Young working at Bell Labs develop idea of using “hexagonal cells”
1973 – First cell phone call – Martin Cooper of Motorola
1G
Analog system Advanced Mobile Phone System
(AMPS) in the US Frequency Division Multiple Access
(FDMA) – Different frequency for each conversation
Issues Listen in with a scanner Spoofing
2G
Digital Time Division Multiple Access (TDMA)
GSM (Global System for Mobile Communications)
D-AMPS (Digital AMPS, superseded by GSM)
iDEN (Integrated Digital Enchanced Network)
Code Division Multiple Access (CDMA) IS-95/cdmaOne
2.5G and 2.75G
2G with always-on data General Packet Radio Service (GPRS)
2.5G for GSM Maxed at about 115 Kbps
1xRTT 2.5G for CDMA Maxed at about 153 Kbps
Enhanced Data rates for GSM Evolution (EDGE) 2.75G Speeds up to 1 Mbps
3G
International Telecommunications Union (ITU) International Mobile Telecommunications-2000 (IMT-2000)
Requires minimum speed of 200 Kbps
3rd Generation Partnership Project (3GPP) – 3G Upgrade for GSM
3GPP2 – 3G Upgrade for CDMA
3G - UMTS
Universal Mobile Telecommunications System (UMTS) by 3GPP
Uses W-CDMA (Wideband CDMA) Handles voice and data Data speeds about 384 Kbps (R99)
to 2 Mbps More on this later…
3G – CDMA2000
3GPP2 Group Backwards compatible with
cdmaOne 1xEV-DO (or just EV-DO) Evolution-
Data Optimized Rev. 0: Max speed of about 2.4 Mbps
download, 153 Kbps upload Rev. A: Max speed of about 3.1 Mbps
download, 1.8 Mbps upload
4G
IMT-Advanced by ITU Global use High-quality services User-friendly High speeds: 1 Gbps stationary, 100 Mbps
mobile Spectrum efficiency IP packet-switched network
LTE (Long Term Evolution) IEEE 802.16 “WiMAX” (Worldwide
Interoperability for Microwave Access)
OFDMA
Orthogonal Frequency-Division Multiple Access
Split channel into sub-carriers User is assigned multiple sub-
carriers: Closer to base gets more sub-carriers
(more bandwidth) Further away, get less sub-carriers, but
use more power OFDM also used in 802.11a/g/n
MIMO
Multiple In – Multiple Out
Diversity Avoid fading due to
multipath interference, shadows
Spatial Multiplexing Use multiple channels
to get higher data rates
LTE
3GPP Verizon, MetroPCS, AT&T, and Sprint Upgrades UMTS Uses MIMO, OFDMA IP-based 700 MHz Band Speed: 100 Mbps download, 50 Mbps
upload
WiMAX
IEEE 802.16e-2005 Scalable OFDMA (SOFDMA) – Scales
the Fast Fourier Transform (FFT) size for different bandwidths
Primarily uses 2.5 GHz band in the US (Clear/Sprint)
Use as backhaul Closer to WiFi Speeds up to 40 Mbps
Not technically 4G
WiMAX and LTE in today’s networks do not meet the IMT-Advanced criteria
Every major wireless 4G network fails to meet IMT-Advanced criteria
ITU accepts WiMAX and LTE as “Pre-4G”
Can also be called 3.9G Networks still calling it 4G
HSDPA, HSUPA, HSPA+
“High Speed Packet Access,” part of 3GPP
D – Downlink, U – Uplink HSDPA – 7.2 Mbps, HSUPA – 1.9 Mbps HSPA+ (Evolved HSPA)
84 Mbps download, 22 Mbps upload MIMO All-IP Option
Still part of 3G, UMTS T-Mobile/AT&T calling it 4G
So what satisfies IMT-Advanced?
LTE-Advanced (3GPP) and WirelessMAN-Advanced (IEEE 802.16m)
Not yet available Will satisfy the 1 Gbps download
speed requirement What will this be called?
Social/Ethical considerations
Is 4G just a marketing term? Bringing broadband to everyone Wireless capacity and Net Neutrality
Sources
IMT-Advanced - Objective and Challenges by K. Jay Miyahara
An Overview of Next-Generation Mobile WiMAX Technology by Sassan Ahmadi
On the Way towards Fourth-Generation Mobile: 3GPP LTE and LTE-Advanced by David Martin-Sacristian, et al.
History of Mobile Telephones (Wikipedia and related articles)