EDGE

Introduction of high-speed data
in GSM/GPRS networks


white paper


2


Table of contents

Preface 3

Executive summary 4

Technical differences
between GPRS and EGPRS 4

Introduction 4
EDGE technology 5
EDGE modulation technique 5
Coding schemes 6
Packet handling 6
Addressing window 7
Measurement accuracy 8
Interleaving 8
Link adaptation 9
Incremental redundancy 9

Impact of EGPRS on existing
GSM/GPRS networks 9

Standardization 10

Background 10
Fulfilling the EDGE Standardization 10
EDGE standard and references 10
Requirements on EDGE 10
Service aspects 10
Architecture 11
User plane protocols 11
Control plane protocols and channels 11

Future evolution of GSM/EDGE
towards WCDMA alignment 12

EGPRS benefits 12
Short-term benefits: Capacity and performance 12
Mid-term benefits: Complementary technology 12
Long-term benefit: Harmonization with WCDMA 13

Acronyms and definitions 14


white paper


Preface

This white paper is intended for global system for
mobile communications (GSM) operators interested in
understanding Ericsson's view on how enhanced data
for global evolution (EDGE) can play an important role
in the evolution toward wideband code division
multiple access (WCDMA).

EDGE can be introduced in two ways: (1) as a
packet-switched enhancement for general packet
radio service (GPRS), known as enhanced GPRS or
EGPRS, and (2) as a circuit-switched data
enhancement called enhanced circuit-switched data
(ECSD). This white paper, however, will only discuss
the packet-switched enhancement, EGPRS.

The purpose of this white paper is to describe EDGE
technology and how it leverages existing GSM
systems and complements WCDMA for further
growth.

The benefits described here are based on Ericsson's
vision of one seamless network for GSM and WCDMA.
The white paper is based on Ericsson's current
experience with operators' deployment processes, our
past experience with technology transitions and our
expertise with all major wireless standards, including
GPRS, EDGE and WCDMA.

3



white paper


Executive summary

EDGE is the next step in the evolution of GSM and IS

136. The objective of the new technology is to
increase data transmission rates and spectrum
efficiency and to facilitate new applications and
increased capacity for mobile use.
With the introduction of EDGE in GSM phase 2+,
existing services such as GPRS and high-speed circuit
switched data (HSCSD) are enhanced by offering a
new physical layer. The services themselves are not
modified. EDGE is introduced within existing
specifications and descriptions rather than by creating
new ones.

This white paper focuses on the packet-switched
enhancement for GPRS, called EGPRS.

GPRS allows data rates of 115 kbps and,
theoretically, of up to 160 kbps on the physical layer.
EGPRS is capable of offering data rates of 384 kbps
and, theoretically, of up to 473.6 kbps. A new
modulation technique and error-tolerant transmission
methods, combined with improved link adaptation
mechanisms, make these EGPRS rates possible. This
is the key to increased spectrum efficiency and
enhanced applications, such as wireless Internet
access, e-mail and file transfers.

GPRS/EGPRS will be one of the pacesetters in the
overall wireless technology evolution in conjunction
with WCDMA. Higher transmission rates for specific
radio resources enhance capacity by enabling more
traffic for both circuit- and packet-switched services.

As the Third-generation Partnership Project (3GPP)
continues standardization toward the GSM/EDGE
radio access network (GERAN), GERAN will be able to
offer the same services as WCDMA by connecting to
the same core network. This is done in parallel with
means to increase the spectral efficiency. The goal is
to boost system capacity, both for real-time and best-
effort services, and to compete effectively with other
third-generation radio access networks such as
WCDMA and cdma2000.

Technical differences
between GPRS and EGPRS

Introduction

Regarded as a subsystem within the GSM standard,
GPRS has introduced packet-switched data into GSM
networks. Many new protocols and new nodes have
been introduced to make this possible.

EDGE is a method to increase the data rates on the
radio link for GSM. Basically, EDGE only introduces a
new modulation technique and new channel coding
that can be used to transmit both packet-switched
and circuit-switched voice and data