The History Of Fundamentals Of Cellular Communications

Published Date: 02 Nov 2017

Mobile broadband is becoming a reality, this generation is growing accustomed to having broadband access wherever they go. People are using their mobiles more and more, they browse the internet, send e-mails and exchange music and videos using 3G phones. Higher peak data rates for the mobile user are in demand. With LTE (Long Term Evolution) mobile users will be capable of more.

This dissertation focuses on the latest mobile wireless standard, Long Term Evolution (LTE) defined by the Third Generation Partnership Project (3GPP) in Release 8 [1]. This dissertation intends to provide an overview of the mobile wireless communication generations leading up to and including LTE.

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This report can be split into three sections; the first section will contain a literature review of the LTE standard and previous generations. The second section consists of a technical review of network simulator (ns3) LTE module for simulation purposes and the final part of the report presenting various scenarios for the LTE network modelled in ns3 with several simulation outputs for performance evaluation and radio resource usage/management. This report will end with the conclusion and further work.

Acknowledgements

Chapter 1 – Introduction

1.1 Aim

1.2 Objectives

1.3

1.4

1.5 Dissertation Structure

This dissertation is structured in 5 chapters as follows:

Chapter 1 – Introduces the aims, objectives and motivation of the research work conducted.

Chapter 2 – Introduces the technical background for the work presented in this dissertation. The evolution of mobile wireless communication will be discussed as well as the present generation LTE – the subject of this dissertation.

Chapter 3 – Introduces the network simulator (ns3)

Chapter 4 – Presents the simulation based testing environment along with scenarios/models

Chapter 2 – Technical Background

This chapter begins with an introduction to the fundamentals of cellular communications providing the reader with the knowledge of the basic components of a cellular system and the ability to identify and describe digital wireless technologies. We then take a brief look at the history and evolution of mobile communications before initiating an in-depth discussion on LTE.

2.1 Fundamentals of Cellular Communications

In a cellular mobile communications system a large number of low-power wireless transmitters are used to create cells. The geographic service area of a wireless communications system is usually divided into hexagonal shaped cells. The power level of the transmitter allow cells to be sized according to the subscribe density and demand within a particular region. Each cell is assigned multiple channels (frequencies); frequencies used in one cell can be reused in another cell provided that the same frequencies are not reused in adjacent neighbouring cells.

2.1.1 System Architecture

A cellular network is made up primarily of cells; a cell is the basic geographic unit of a cellular system. Cells are base stations transmitting over small geographic areas. The area of coverage for every cell varies depending on the landscape. Diagrammatically, cells are often displayed as hexagonal shapes that fit together. In reality a cells outer boundary is loosely defined as the signal strength gradually reduces, and towards the boundary (edge) of the cell performance falls.

[hexagonal cell figure]

Frequency reuse

The key characteristic of a cellular network is the ability tore-use frequencies to increase both coverage and capacity.

The concept of frequency reuse is based on assigning to each cell a group of radio channels used within a small geographic area.

Handover

2.1.2 Cellular System Structure

The simple structure of a cellular communications network consist of the following:

2.2 History and progression of mobile communications

2.3 Long Term Evolution (LTE)

2.3.1 Architecture

2.3.2 OFDMA

2.3.3 SC-FDMA

2.3.4 MIMO

2.3.5 Protocol Stack

3. Network Simulator 3 (ns3)

Chapter 2 – Technical Background

This section containdiscussion on the important technical aspects of 3GPP LTE release 8.

2.1 Long Term Evolution

[Motiviation / history – talk about wireless tech growth]

3GPP work o the Evolution of the 3G Mobile System started in November 2004

LTE base on the success of HSPA, hspa growth I sbased on the uptake of mobile data services wordwide…more than 250 newtorks worldwide have already cmmerically launched hspa

Mobile data traffic is growing exponentially, caused by mobile internet offerins and improved user experience with new device types.

LTE was designed from the start with the goal of evolving the radio access technology under the assumption that all services would be packet-switched, rather than the circuit-switched model of the earlier generations.

*Also talk about the evolution of the non-radio aspects of the complete system. SAE (System Architecture Evolution), EPC (Evolved Packets Core)

*Release 9 and Release 10 – LTE Advanced

Requirements and Targets for the Long Term Evolution. The requirements and targets are defined in LTE Release 8 being finalized in June 2005

Summarized as follows:

- Increase peak data rates: 100Mbit/s downling and 50Mbit/s uplink

- reduction of radio access network (RAN) latency o 10ms

- improved spectrum efficiency (2 to 4 times compared with HSPA Release 6)

- Improved broadcasting

-IP-optimized

- Scalable bandwidth

-

-

Table for key performance requirements:

LTE is the latest generation of the 3GPP standards. The LTE standard specifies an IP-only network supporting data rates up to 150 Mbps. These high data rates will enables new applications and services such as voice over IP, streaming multimedia, videoconferencing or even a high-speed cellular modem.

Motivation for LTE

HSPA growth is based on the uptake of mobile data services worldwide. More than 250 networks worldwide have already commercially launched hspa.

Mobile data traffic is growing exponentially, caused by mobile internet offerings and improved user experience with new device types.

LTE is accepted worldwide as the long term evolution perspective for today’s 2G and 3G networks based on WCDMA/HSPA, GSM/EDGE, TD-SCDMA AN CDMA2000 technologies

[talk about when work on LTE was initiated] 3GPP release 7 study item "Evolved UTRA and UTRAN" December 2004

[talk about major requirements for LTE, all mentioned in the study item rel7

Peak data rates

Improved spectrum efficiency

Improved latency

Radio access network latency (user plane ue-rnc-ue) below 10ms

Significantly reduced control plane latency

Support for scalable bandwidth

Support of paired and unpaired spectrum (fdd and tdd mode)

Support for interworking with legacy networks

Cost-efficiency:

Reduced capital and operational expenditures (capex, opex) including backhaul

Cost-effective migration from legacy networks

A detailed summary of requirements has been captured in 3GPP TR 25.913 "Requirements for Evolved UTRA (E-UTRA) and Evolved UTRAN (E-UTRAN)"

]

[Diagram of evolution of UMTS FDD and TDD]

OFDM? SINGLE CARRIER TRANSMISSION VS ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING

Difference between ofdm and ofdma

Lte conventional ofdma

Network and protocol architecture LTE/SAE

2.1.1 LTE Enabling Technologies

]

Lte technology basics

Key parameters

Ofdma and downlink frame structure

Sc-fdma and uplink frame structure

Network ad protocol architecture

Lte ue categories

Radio procedures

Cell search

System information broadcast

Random access

Eps bearer setup

Downlink and uplink data transmission

Mobility

mimo

Simulation Results