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Author:Pitkänen, Sampo
Title:Optimal Reception of 64 Quadrature Amplitude Modulation in High-Speed Downlink Packet Access
64-QAM –signaalin optimoitu vastaanottomenetelmä HSDPA:ssa
Publication type:Master's thesis
Publication year:2008
Pages:xvi + 62      Language:   eng
Department/School:Sähkötekniikan laitos
Main subject:Informaatiotekniikka   (T-115)
Supervisor:Simula, Olli
Instructor:Huuhtanen, Timo
Electronic version URL: http://urn.fi/urn:nbn:fi:tkk-010335
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark S80     | Archive
Keywords:3G
WCDMA
HSDPA
64-QAM
demodulation
demodulointi
Abstract (eng):High-speed downlink packet access (HSDPA) is a feature introduced to the universal mobile telecommunications system (UMTS) in 2002.
It allows data rates of up to 14.4 Mbps in the downlink.
In 2007 new features were standardized to HSDPA, including 64 Quadrature Amplitude Modulation (64-QAM).

64-QAM allows more data to be transmitted on the same bandwidth, increasing the HSDPA peak data rate to 21.6 Mbps.
Transmitters and receivers must be updated with new algorithms to support this new modulation type.
On the terminal side the amplitude of the signal must first be precisely estimated so that it can be demodulated correctly.
Then a demodulation algorithm with good enough accuracy must be applied.
Similar algorithms were already used with older HSDPA versions, but 64-QAM is much more sensitive to errors.

In this thesis, three amplitude estimation and three demodulation algorithm candidates were considered.
A physical layer HSDPA simulator with realistic parameters was used to compare the algorithms.

There was no clear winner when selecting the best way to estimate the amplitude, but two of the algorithm candidates proved to be better than the third.
The best demodulation algorithm for practical applications turned out to be a simplified MAP optimum detector that models the demodulation as a one-dimensional problem.
Abstract (fin):HSDPA on vuonna 2002 UMTS-verkkoihin lisätty ominaisuus.
Sen avulla laskevalla siirtotiellä mobiililaitteiden huippunopeudeksi saadaan 14.4 megabittiä sekunnissa.
Vuonna 2007 standardoitiin uusia HSDPA-ominaisuuksia, niiden mukana uusi modulaatiotyyppi 64-QAM.

64-QAM:in avulla suurin siirtonopeus saadaan nostettua 21.6:n megabittiin sekunnissa.
Sekä lähettimiä että vastaanottimia on päivitettävä uuden modulaatiotyypin tukemiseksi.
Vastaanottopäässä signaalin amplitudi täytyy ensin estimoida tarkasti jotta signaali voidaan vastaanottaa oikein.
Signaali pitää vielä tämän jälkeen demoduloida riittävällä tarkkuudella.
Samankaltaisia algoritmeja on käytetty jo vanhemmissa HSDPA-versioissa, mutta 64-QAM on huomattavasti herkempi virheille.

Tässä työssä amplitudiestimointia ja demodulointia varten testattiin kolmea eri algoritmivaihtoehtoa.
Algoritmien vertailuun käytettiin fyysisen kerroksen HSDPA-simulaattoria, jossa käytettiin standardin mukaisia realistisia parametreja.

Lopputuloksena yksiselitteisesti parasta tapaa estimoida amplitudia ei löytynyt, mutta kaksi ehdokkaista osoitti hyviä ominaisuuksia.
Parhaaksi demodulointialgoritmiksi osoittautui yksinkertaistettu versio optimaalisesta MAP-ilmaisimesta, joka hoitaa demoduloinnin yksiulotteisesti.
ED:2008-02-29
INSSI record number: 35381
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