From GSM to LTE

Medienforum NRW 2011

From GSM to LTE – An Introduction

Martin Sauter

Martin Sauter - www.wirelessmoves.com - From GSM to LTE - Medienforum NRW - June 2011 1

Who Am I
• (Wireless) Network Researcher and Blogger
• Book Author
• Project Manager working for a Mobile Network
Operator


Technology Overview: GSM
(First Networks 1992/93)


GSM Characteristics
• Originally designed for telephony
• 200 kHz (0.2 MHz) carriers (channels)
• 8 timeslots per channel = 8 phone calls
• 3 sectors (120°) per base station is typical
• Several carriers per sector is typical
• Max range: Up to ~30 km
• Typical range: 500m in cities for capacity
reasons

Typical Base Station Antennas

Picture: Martin Sauter


Technology Overview: UMTS


UMTS / HSPA Network Architecture

The bread and
butter service!

Source: Beyond 3G, Bringing Networks, Terminals and

GSM / UMTS / LTE BTS'es Today

Pictures: Martin Sauter


HSPA today
• Frequency Bands (→ http://tinyurl.com/4pdr3o)
• Speeds, Always-On, Keep-Alive Signaling
• Activity States (DCH, Cell-FACH, Cell-PCH, URA-PCH, Idle →
http://tinyurl.com/2w5c9zj)
• Latency
• Power Consumption, Fast Dormancy
• → Impact on Services
• → Impact on Network
(Further Reading: http://tinyurl.com/2e6dxkt)


HSPA+: Higher Speeds And More
Service Benefits
• New features beyond higher speeds and their
impact on services, e.g.:
• Lower latency
• Less power consumption in idle mode
• Faster and fewer state switches

Further background: http://en.wikipedia.org/wiki/Hsdpa

Higher Speeds But Not Everywhere
Ericsson Review article shows maximum speed
depending on location.

http://tinyurl.com/dk6c2p
(not included due to copyright reasons but available via this link, see Figure 2)


The Backhaul Impact on Services
• For both HSPA and LTE, the legacy backhaul
architecture based on x * 2 Mbit/s E-1 links is
by far not sufficient anymore and far too
expensive.
• Alternatives:
• Fiber – Very fast but expensive rollout
• VDSL – In combination with VDSL + fiber network
deployment for super high speeds for homes.
• Microwave Ethernet

Technology Overview: LTE


LTE Network Overview

The bread and

Source: Martin Sauter, From GSM to LTE
butter service
is missing!


OFDMA – What is That?

OFDMA = Orthogonal Frequency
Division Multiple Access


Bandwidth: How Much and Where?
• 1.25 – 20 MHz: Impacts max. possible speed
• 10 MHz in 800 MHz Digital Dividend per Network
• 15-20 MHz Channels in 1800 and 2600 MHz
• Lots of bands globally, even locally, everything
between 700 and 3600 MHz. Big issue!
• → The „hedgehog phone“ - is it realistic?
LTE Bands - For further reading: http://tinyurl.com/3ywx2vs


LTE = IP Services only
• Pros:
• Simplified Network Infrastructure
• Less Latency
• Less Complexity
• Cons:
• Complex integration of voice services with the
ability to hand-over to GSM or UMTS when leaving
the coverage area.


GSM, HSPA and LTE side by side
• GSM for voice centric devices, maximum
coverage and international voice roamers.
• UMTS (HSPA) for mobile devices with a strong
voice integration (smartphones) and high speed
data (3G USB dongles).
• LTE to provide high speed Internet access in
rural areas (800 MHz), indoor coverage (cities)
and high capacity (cities, 1800 and 2600 MHz).
(LTE USB sticks, pads, notebooks, etc.).

When Will GSM be Switched Off?
• NTT DoCoMo to switch-off 2G in 2011 – special
case (http://tinyurl.com/2uprcyx)
• GSM will remain strong well over this decade
and beyond. Reasons: 3G still not ubiquitous,
equipment refreshes, roaming, new entrants,
new markets, handset prices.
Thoughts from back in 2007: http://tinyurl.com/34t7pfe)
• Phaseout Architectures (http://tinyurl.com/375v5yd)
• Virtual GSM (http://tinyurl.com/2vx939b)

Thank You!

Picture by Fabian Schustek


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