27th February 2001

TELIT GROUP Industries for Telecommunications 1

27th February 2001

Satellite Personal Communications Systems (S-PCS): the Globalstar System and evolutionary paths towards 3G

SCHOOL ON DIGITAL

AND MULTIMEDIA

COMMUNICATIONS

USING TERRESTRIAL

AND SATELLITE

RADIO LINKSTELIT MOBILE TERMINALS

Giovanni De MaioTelit Mobile Terminals S.p.A.Project Manager - System EngineeringSatellite User Terminal DivisionVia Vitorchiano, 81 - [email protected]


Globalstar System Overview


Globalstar is a system that provide digital telephony with a global coverage, by means of a satellite constellation working in a Low Earth Orbit (LEO).

Globalstar allows access to the terrestrial networks, both fixed and mobile, interworking with them in a complementary way.

In areas not covered by the terrestrial networks, the Globalstar Terminal can be set to switch automatically from the terrestrial to the satellite mode.

The system is designed in order to maximise coverage in the temperate areas.

Globalstar System

Overview

Globalstar service aspects


Gateway

Mobile Portable Fixed

Space Segment

User Segment

Ground Segment

Terrestrial NetworkPLMN/PSTN

GBO

GDN

SOCC

GOCC

Globalstar System

Overview

Globalstar System Architecture

GOCC: Ground Operations Control Center

SOCC: Space Operations Control Center

GDN: Globalstar Data Network

GBO: Globalstar Business Office


Globalstar constellation

At least 7.5 years life time

Weight: 450 Kg

1100 Watts against 2000 circuits

Distance 1414 Km at 52°

8 orbital planes e 6 equally spaced satellites per orbit

Circular orbit period 113 minutes

48 LEO satellites:

User terminals can be served by a satellite 10 to 15 minutes out of each orbit.

Globalstar System

Overview

Space Segment


Earth Surface Coverage

Globalstar System

Overview

Space Segment

The system is designed in order to maximise coverage in the temperate areas.


Multiple Coverage (48 SATELLITES; 10° ELEVATION)

At LATITUDE 40°:

At least 4 satellites for 38% of time

At least 3 satellites for 87% of time

At least 2 satellites always visible

At least one satellite always visible for LATITUDE<70°

Globalstar System

Overview

Space Segment


immagini

immagini

User and feeder links

Globalstar System

Overview

Space Segment

Satellites are of the non regenerative type: they simply perform a transparent relay of the signals in both Forward and Reverse links


Space SegmentFrequency channels G

lobalstar System O

verview


Space Segment

1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z

1 6 2 6 . 5 M H z

1 6 2 5 . 4 9 0 M H z

1 6 1 0 . 0 M H z

7 3 0 k H z

1 6 2 4 . 2 6 0 M H z 1 6 2 3 . 0 3 0 M H z

1 6 2 1 . 8 0 0 M H z 1 6 2 0 . 5 7 0 M H z

1 6 1 9 . 3 4 0 M H z 1 6 1 8 . 1 1 0 M H z

1 6 1 6 . 8 8 0 M H z 1 6 1 5 . 6 5 0 M H z

1 6 1 4 . 4 2 0 M H z 1 6 1 3 . 1 9 0 M H z

1 6 1 1 . 9 6 0 M H z 1 6 1 0 . 7 3 0 M H z

1 6 . 5 M H z F i l e : L - B a n d

1 0 1 0 k H z

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3

2 5 0 0 . 0 M H z

2 4 9 9 . 1 5 0 M H z

2 4 8 3 . 5 M H z

2 4 9 7 . 9 2 0 M H z 2 4 9 6 . 6 9 0 M H z

2 4 9 5 . 4 6 0 M H z 2 4 9 4 . 2 3 0 M H z

2 4 9 3 . 0 0 0 M H z 2 4 9 1 . 7 7 0 M H z

2 4 9 0 . 5 4 0 M H z 2 4 8 9 . 3 1 0 M H z

2 4 8 8 . 0 8 0 M H z 2 4 8 6 . 8 5 0 M H z

2 4 8 5 . 6 2 0 M H z 2 4 8 4 . 3 9 0 M H z

1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z 1 . 2 3 M H z

8 9 0 k H z

1 6 . 5 M H z F i l e : S - B a n d

8 5 0 k H z

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3

Forward and Reverse User links channels or Sub-Beams

S-Band Forward User Linkchannels (Sub-Beams)

L-Band Reverse User Link channels (Sub-Beams)

Globalstar System

Overview


Space Segment Sub-Beams to Gateways Assignment

Overlapping Beams will transmit Sub-Beams for both Gateways

Globalstar System

Overview


Space Segment Globalstar System

Overview

PILOT: unmodulated DS SS signal transmitted by the Gateway (employed to acquire the timing, as phase reference for demodulation and to handoff)

SYNC: channel carrying a repeating message for terminal synchronization

PAGING: provides system access information for registering UT’s lets a phone know that a call is coming in or that there is a message in voice mail for SMS to reply to a UT trying to place a call, for handoff messaging when not in a call

TRAFFIC: communication path between a UT and a Gateway, which implies a Forward and a Reverse Traffic Channel pair; for voice, data, signaling (when in a call)

ACCESS: slotted random access channel for call originations, responses to pages and registrations

Globalstar Air Interface Channels


Space Segment Globalstar System

Overview

Example of a Forward CDMA Channel

The above example shows a particular assignment of the overall 128 channels (codes)

within a 1.23 MHz Forward Channel to Pilot, Sync, Paging and Traffic functionalities


Space Segment

Acquisition Search Space

Globalstar System

OverviewThe acquisition process consists of a research of the

pilot signal in a three dimensional search space: its

dimensions are PN Code, PN Timing and Frequency Doppler Shift. Note that the Frequency Doppler Shift

is actually a quite minor issue for acquisition in a

terrestrial environment (e.g. IS-95). Less acquisition

times could be achieved in the Warm Start case by

exploiting information acquired during the previous

start up.


Channel 5

COMBINER

RECEIVER 1

RECEIVER 2

RECEIVER 3

Globalstar Handset

Globalstar Gateway

S1S1

S2 S2

Globalstar 1 Globalstar 2

Channel 5

Decoder & Vocoder

Globalstar System

Overview

Space SegmentDiversity Operation

Diversity operation provides significant advantages in both forward and reverse link transmission (combining is carried out by the user terminal and by the Gateway, respectively)

Spatial diversity in the forward link is illustrated: combining is performed on up to three received signal replicas


Space Segment

Hard Handoff: Intrabeam Handoff (change of frequency)

Globalstar Handoffs Globalstar System

Overview


Globalstar System

Overview

Ground Segment

GOCC: Ground Operations Control Center

SOCC: Space Operations Control Center

SPCC: Service Provider Control Center

Components

TT&C: Tracking, Telemetry and Command

GDN: Globalstar Data Network

GCC: Globalstar Control Center (incorporates GOCC, SOCC and GBO into a single facility)

GBO: Globalstar Business Office (for financial and administrative aspects:business arrangements with SP’s, billing, marketing and sales efforts


Ground Segment

RFSUBSYSTEM

IS-41MSCVLR

BSC

CDMASUBSYSTEM

GSMMSCVLR

GATEWAY

GSM PLMN

HLRGSM

GMSCVLR

AInterface

PSTN

PSTN

PLMN

LOCALGSM MSC/VLR

Gateway - PLMN Interconnection

Globalstar System

Overview


User Segment

Main Characteristics:• GSM phase II/Globalstar Compliant• Voice/fax/data/SMS/SS GSM/GLB* Services• Position Location (up to 300 m)*• Automatic/manual Mode Select • Standard Battery 1600 mAh• Overall Weight 415 gr.• Overall Dimensions 21x6x4 cm• Stand-by and talk time in G* [2h - 7h]• Stand-by and talk time in GSM [4h - 83h*]• Graphic Display 4x12 characters + icons

Accessories:• Car Kit, Marine Kit, Home Kit• Data Terminal Adapter• Leather case• Cigarette Lighter Charger (12 Volt)• Desk Top Charger• Solar Charger

* if supported by the network

Globalstar User Terminals Status: Telit SAT 550 Globalstar System

Overview


Globalstar User Terminals Status: Telit SAT 650User Segment

Front shellController board

ShieldRadio board

Shield

Rear shell

Globalstar System

Overview


GS User-to-GS User Operation

In this case satellites in view offer, as usual, bent-pipe relays between users and relevant Gateways; whilst the Gateway-to-Gateway connection relies onto the PSTN backbone

Call Processing Globalstar System

Overview


Call Processing Simplified Call Procedure

A

User tries to place a call through the Globalstar Satellite service:

if the called party is a wireline or terrestrial cellular-based end user ( ), the call is routed through either the PSTN or PLMN

if the called party is a satellite-based end user ( ) the call is routed back through the Gateway up to the Globalstar Satellite and down to the user

Globalstar System

Overview

A

B

B

C

C


3G S-PCS: The Next Step


Wireless Evolution through the Generations series

1G

2G

3G

Analogue voice (AMPS- Advanced Mobile Phone Standard, TACS-Total Access Communications System,... )

Digital voice, low data rate applications [GSM, IS-54 (TDMA), IS-95 (CDMA), GLOBALSTAR, IRIDIUM…]

UMTS/IMT 2000 Global Standard for wireless multimedia

3G S-PC

S: The Next Step


International Mobile Telecommunications-2000 (IMT-2000) are third generation mobile systems which are scheduled to start service around the year 2000 subject to market considerations. They will provide access, by means of one or more radio links, to a wide range of telecommunications services supported by the fixed telecommunication networks (e.g. PSTN/ISDN/IP), and to other services which are specific to mobile users A range of mobile terminal types is encompassed, linking to terrestrial and/or satellite based networks, and the terminals may be designed for mobile or fixed use

As a strategic priority of ITU, IMT-2000 provides framework for worldwide wireless access by linking the diverse system of terrestrial and/or satellite based networks.

I M T - 2 0 0 0 T h e I T U v i s i o n o f g l o b a l w i r e l e s s a c c e s s

i n t h e 2 1 s t c e n t u r y

S a t e l l i t e

M a c r o c e l l M i c r o c e l l

U r b a nI n - B u i l d i n g

P i c o c e l l

G l o b a l

S u b u r b a n

B a s i c T e r m i n a lP D A T e r m i n a l

A u d i o / V i s u a l T e r m i n a l

IMT 2000

IMT is a result of the collaboration of many entities, inside the ITU (ITU-R Radiocommunication Sector and ITU-T Telecommunication Standardization Sector ), and outside the ITU (3GPP, 3GPP2, etc.)

3G S-PC

S: The Next Step


3G S-PC

S: The Next Step

Satellite Air interface selection - ITU Process

Satellite Wide Band CDMA (ESA RTT- Radio Transmission Technology). Adaptation of UMTS UTRA W-CDMA to the satellite environment. Suited for global systems (LEO/MEO). (SRI-A)

Formerly TTA- SAT.

(SRI-C)

(ESA RTT) Commonalities with ETSI UTRA TDD. Attractive for regional systems (HEO/GEO). (SRI-B)Harmonization

on going


S-UMTS stands for the Satellite component of the Universal Mobile Telecommunication System. S-UMTS systems will complement the terrestrial UMTS (T-UMTS) and inter-work with other IMT-2000 family members through the UMTS core network. S-UMTS will be used to deliver 3rd generation mobile satellite services (MSS) utilizing either low (LEO) or medium (MEO) earth orbiting, or geostationary (GEO) satellite(s). S-UMTS systems are based on terrestrial 3GPP specifications and will support access to GSM/UMTS core networks.

Due to the differences between terrestrial and satellite channel characteristics, some modifications to the terrestrial UMTS (T-UMTS) standards are necessary. Some specifications are directly applicable, whereas others are applicable with modifications. Similarly, some T-UMTS specifications do not apply, whilst some S-UMTS specifications have no corresponding T-UMTS specification.

First set of ETSI Technical Specs approved (1/2) 3G S-PC

S: The Next Step


First set of ETSI Technical Specs approved (2/2)

Satellite Component of UMTS/IMT 2000; A-family;

Part 1: Physical channels and mapping of transport channels into physical channels (S-UMTS-A 25.211)

Part 2: Multiplexing and channel coding (S-UMTS-A 25.212)

Part 3: Spreading and modulation (S-UMTS-A 25.213)

Part 4: Physical layer procedures (S-UMTS-A 25.214)

3G S-PC

S: The Next Step


S-UMTS Air Interface transport and physical channels

The mapping of transport channels onto physical channels is a fundamental function performed by the physical layer

3G S-PC

S: The Next Step


Worldwide Frequency Bands

ERC (European Radiocommunications Committee) assignments to MSS:– 2 x 30 MHz (1980 - 2010 MHz and 2170 - 2200 MHz)– 15 MHz available from 2000 (1995 - 2010 MHz and 2185 - 2200 MHz)– 30 MHz available from 2005 (1980 - 2010 MHz and 2170 - 2200 MHz)– 15 MHz assigned TDMA systems (S-PCS) (1995 - 2010 MHz and 2185 -2200 MHz)

2X30 MHz in S-Band allocated to MSS, adjacent to spectrum allocation for terrestrial systems

3G S-PC

S: The Next Step


Spectrum Needs

More bandwidth requested

Terrestrial PCS are competing for spectrum allocation

WRC2000 (2000 World Radiocommunications Conference) postponed

a decision on satellite phone frequencies until 2003, which means that

before 2003 a viable satellite consortium needs to be established or else

the already allocated spectrum will be lost and available in favour of T-

UMTS

3G S-PC

S: The Next Step


From 3GPP 3G TS 22.105: UMTS Service aspects, Services and Service Capabilities

3G S-PC

S: The Next Step


Again from 3GPP 3G TS 22.105 3G S-PC

S: The Next Step


UMTS QoS Classes (1/2)

Differently from systems belonging to the previous generations, UMTS allows to enjoy the use of

bearers, defined by means of bearer service attributes, and not of end-services/applications directly.

To aid the application-to-bearer mapping, QoS classes for homogeneous end-services have been

devised, which are themselves service attributes, characterized by a set of specific service attributes,

as from the following viewgraph.

3G S-PC

S: The Next Step


UMTS QoS Classes (2/2)A

ttrib

utes

for U

MTS

Bea

rer S

ervi

ces

3G S-PC

S: The Next Step


The “Satellite Access Network”

The access network infrastructure for the S-UMTS is here envisaged with minimal differences compared to the terrestrial 3G infrastructure. The satellite should play the role of the T-UMTS Node B (Base Station) but it’s to be deepened whether the same terrestrial Iur and Iub interfaces could be employed, which have been devised for T-UMTS between RNC’s and between RNC and Node B, respectively.

Iub ?

Iur ?

3G S-PC

S: The Next Step


S-UMTS Terminal : envisaged architecture

A digital predistortion in the TX path is envisaged, performed by the loop “DSP-Up conversion path-Antenna set-Feedback”. The same feedback line, shown in figure, is used to perform a dinamic adjustment, to improve the linearity of the receiving section.

The Control Processor manages the exchange of data/addressing information between the DSP and the ASIC

The core of the system is the DSP, responsible of most of the baseband processing; the support of dedicated ASICs for particular heavy computational operations like rake-decoding/Interference mitigation can be necessary depending on DSP computational power. In this last case, a dedicated bus between the DSP and the ASIC could also be needed, or the ASIC should directly communicate with the AD/DA converters and then with the DSP.

3G S-PC

S: The Next Step

Date post:	21-Mar-2016
Category:	Documents
Upload:	carnig
View:	41 times
Download:	1 times

27th February 2001

Documents