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1、Jan De Nayerlaan, 5 B-2860 Sint-Katelijne-Waver Belgium www.denayer.beSpread Spectrum (SS)applicationsir. J. Meel jmedenayer.wenk.beStudiedag Spread Spectrum 6 okt. 99In the period of nov. 1997 - nov. 1999 a Spread Spectrum project was worked out at the polytechnic DE NAYER instituut . The goal of t
2、his project was the hardware/software implementation of a Direct Sequence Spread Spectrum (CDMA) demonstrator in the 2.4 GHz ISM band. A measurement environment (Vector Signal Analyzer, IQ-modulator, Bit Error Rate Tester) was build out, resulting in a set of experiments based on this demonstrator.
3、The project results where communicated with SMO s (Small and Medium Organisations) interested in Spread Spectrum. These notes were used to introduce the SMO s in the subject of Spread Spectrum.This Spread Spectrum project was sponsered by:Vlaams Instituut voor de bevordering van het Wetenschappelijk
4、 Technologisch onderzoek in de industrie (Flemisch Gouvernment)Sirius Communications Rotselaar - BelgiumV2 dec 99DE NAYER (ir. J. Meel) IWT HOBU-fonds Spread Spectrum 2CONTENTS1.SPREAD SPECTRUM APPLICATIONS.31.1WLAN IEEE 802.11.3 1.1.1Network Topology .3 1.1.2Physical Layer (Radio Technology).4 1.2G
5、PS (GLOBAL POSITIONING SYSTEM).7 1.3IS-95.13 1.3.1Network Architecture.13 1.3.2Forward Link Radio Transmission.14 1.4W-CDMA.17DE NAYER (ir. J. Meel) IWT HOBU-fonds Spread Spectrum 31. Spread Spectrum Applications1.1 WLAN IEEE 802.11IEEE 802.11 is the first internationally recognized standard for Wir
6、eless Local Area Networks (WLAN), introducing the technology of mobile computing.1.1.1 Network TopologyAd-hoc NetworkAn Ad-hoc network or Independent Basic Service Set (IBSS) is a simple network where communications are established between two or more wireless nodes or Stations (STAs) in a given cov
7、erage area without the use of an Access Point (AP) or server. The STAs recognize each other and communicate directly with each other on a peer-to-peer level.STA1STA3STA2IBSSInfrastructure NetworkAn Infrastructure network (or client/server network) is a more flexible configuration in which each Basic
8、 Service Set (BSS) contains an Access Point (AP). The AP forms a bridge between the wireless and wired LAN. The STAs do not communicate on a peer-to-peer basis. Instead, all communications between STAs or between an STA and a wired network client go through the AP. APs are not mobile and form part o
9、f the wired network infrastructure. The Extended Service Set (ESS) consists of a series of BSSs (each containing an AP) connected together by means of a Distribution System (DS). Although the DS could be any type of network (including a wireless network), it is almost invariably an Ethernet LAN. Wit
10、hin an ESS, STAs can roam from one BSS to another and communicate with any mobile or fixed client in a manner which is completely transparant in the protocol stack above the MAC sublayer. The ESS enables coverage to extend well beyond the range of the WLAN radio.DE NAYER (ir. J. Meel) IWT HOBU-fonds
11、 Spread Spectrum 41.1.2 Physical Layer (Radio Technology)Spreading and ModulationIEEE 802.11 defines three variations of the Physical Layer: Infrared (IR) and two RF transmissions in the unlicensed 2.4 GHz ISM-band, requiring spread spectrum modulation: DSSS (Direct Sequence Spread Spectrum) and FHS
12、S (Frequency Hopping Spread Spectrum). Only the RF transmission has significant presence in the market.1MbpsSpreadingdtpntDBPSK11 chip BarkerRF (2.4 GHz)11 Mcps11 MspsDSSSFHSSSpreadingS / PdtpntQDQPSK11 chip BarkerRF (2.4 GHz)IpntfRF2Mbps11 Msps11McpsFWSpreadingdtpntFH ModulatorPN codeRF (2.4 GHz)2-
13、GFSK Modulatorfhi1 Mbps1 Msps1 MspsFWSpreadingdtpntFH ModulatorPN codeRF (2.4 GHz)4-GFSK Modulatorfhi2 Mbps1 Msps1 MspsDSSSThe DSSS physical layer uses an 11-bit Barker sequence to spread the data before it is transmitted. This sequence gives a processing gain of 10.4 dB, meeting the minimum requirements of FCC 15.247 and ETS 300 328. The 11 Mcps baseband stream is modulated onto a carrier f
