Hi All, I need some specific information on channel equalizer implementations of practical GSM receivers. I assume time domain equalizers are used in GSM phones, but I would like to the equalizer algorithms and training algorithms and convergence algorithms used by them. I highly appreciate if anyone can share his/her experience on this regard. All the references are highly appreciated. Thanks in advance. _____________________________ Posted through www.DSPRelated.com

# Equalizers implemented in GSM receivers

Started by ●March 18, 2014

Reply by ●March 18, 20142014-03-18

On Tue, 18 Mar 2014 02:51:09 -0500, "Dan25" <98432@dsprelated> wrote:>Hi All, > >I need some specific information on channel equalizer implementations of >practical GSM receivers. I assume time domain equalizers are used in GSM >phones, but I would like to the equalizer algorithms and training >algorithms and convergence algorithms used by them. > >I highly appreciate if anyone can share his/her experience on this regard. >All the references are highly appreciated. > >Thanks in advance.Receiver details for specific impementations are usually kept proprietary, so you may not be able to get much info on what is actually done, and it probably varies a fair amount from implementation to implementation. There are training sequences built into the GSM frame structure, so there are a lot of different tecqniques that can be used to train the equalizer. Eric Jacobsen Anchor Hill Communications http://www.anchorhill.com

Reply by ●March 18, 20142014-03-18

>On Tue, 18 Mar 2014 02:51:09 -0500, "Dan25" <98432@dsprelated> wrote: > >>Hi All, >> >>I need some specific information on channel equalizer implementations of >>practical GSM receivers. I assume time domain equalizers are used in GSM >>phones, but I would like to the equalizer algorithms and training >>algorithms and convergence algorithms used by them. >> >>I highly appreciate if anyone can share his/her experience on thisregard.>>All the references are highly appreciated. >> >>Thanks in advance. > >Receiver details for specific impementations are usually kept >proprietary, so you may not be able to get much info on what is >actually done, and it probably varies a fair amount from >implementation to implementation. > >There are training sequences built into the GSM frame structure, so >there are a lot of different tecqniques that can be used to train the >equalizer. > >Eric Jacobsen >Anchor Hill Communications >http://www.anchorhill.com >I'm pretty sure that the intended "equalization" method for a GSM burst is maximum likelihood sequence estimation. -Doug _____________________________ Posted through www.DSPRelated.com

Reply by ●March 18, 20142014-03-18

On Tue, 18 Mar 2014 13:33:59 -0500, "DougB" <60916@dsprelated> wrote:>>On Tue, 18 Mar 2014 02:51:09 -0500, "Dan25" <98432@dsprelated> wrote: >> >>>Hi All, >>> >>>I need some specific information on channel equalizer implementations of >>>practical GSM receivers. I assume time domain equalizers are used in GSM >>>phones, but I would like to the equalizer algorithms and training >>>algorithms and convergence algorithms used by them. >>> >>>I highly appreciate if anyone can share his/her experience on this >regard. >>>All the references are highly appreciated. >>> >>>Thanks in advance. >> >>Receiver details for specific impementations are usually kept >>proprietary, so you may not be able to get much info on what is >>actually done, and it probably varies a fair amount from >>implementation to implementation. >> >>There are training sequences built into the GSM frame structure, so >>there are a lot of different tecqniques that can be used to train the >>equalizer. >> >>Eric Jacobsen >>Anchor Hill Communications >>http://www.anchorhill.com >> >I'm pretty sure that the intended "equalization" method for a GSM burst is >maximum likelihood sequence estimation. > >-DougThe standards don't specify implementation, just the waveform. Implementers are free to do whatever they wish in the receiver. Sometimes the air interface waveform is designed with some candidate implementation in mind, but one is always free to do their own tricks in the receiver.>_____________________________ >Posted through www.DSPRelated.comEric Jacobsen Anchor Hill Communications http://www.anchorhill.com

Reply by ●March 18, 20142014-03-18

>On Tue, 18 Mar 2014 13:33:59 -0500, "DougB" <60916@dsprelated> wrote: > >>>On Tue, 18 Mar 2014 02:51:09 -0500, "Dan25" <98432@dsprelated> wrote: >>> >>>>Hi All, >>>> >>>>I need some specific information on channel equalizer implementationsof>>>>practical GSM receivers. I assume time domain equalizers are used inGSM>>>>phones, but I would like to the equalizer algorithms and training >>>>algorithms and convergence algorithms used by them. >>>> >>>>I highly appreciate if anyone can share his/her experience on this >>regard. >>>>All the references are highly appreciated. >>>> >>>>Thanks in advance. >>> >>>Receiver details for specific impementations are usually kept >>>proprietary, so you may not be able to get much info on what is >>>actually done, and it probably varies a fair amount from >>>implementation to implementation. >>> >>>There are training sequences built into the GSM frame structure, so >>>there are a lot of different tecqniques that can be used to train the >>>equalizer. >>> >>>Eric Jacobsen >>>Anchor Hill Communications >>>http://www.anchorhill.com >>> >>I'm pretty sure that the intended "equalization" method for a GSM burstis>>maximum likelihood sequence estimation. >> >>-Doug > >The standards don't specify implementation, just the waveform. >Implementers are free to do whatever they wish in the receiver. >Sometimes the air interface waveform is designed with some candidate >implementation in mind, but one is always free to do their own tricks >in the receiver. > >>_____________________________ >>Posted through www.DSPRelated.com > >Eric Jacobsen >Anchor Hill Communications >http://www.anchorhill.com >Thanks Doug and Eric. Do you have any references which I can use to find the implementations ? I want to get an accurate number for complexity of channel equalizer and estimator algorithms. _____________________________ Posted through www.DSPRelated.com

Reply by ●March 20, 20142014-03-20

On Tuesday, March 18, 2014 9:06:05 PM UTC-4, Dan25 wrote:> >On Tue, 18 Mar 2014 13:33:59 -0500, "DougB" <60916@dsprelated> wrote: > > > > > >>>On Tue, 18 Mar 2014 02:51:09 -0500, "Dan25" <98432@dsprelated> wrote: > > >>> > > >>>>Hi All, > > >>>> > > >>>>I need some specific information on channel equalizer implementations > > of > > >>>>practical GSM receivers. I assume time domain equalizers are used in > > GSM > > >>>>phones, but I would like to the equalizer algorithms and training > > >>>>algorithms and convergence algorithms used by them. > > >>>> > > >>>>I highly appreciate if anyone can share his/her experience on this > > >>regard. > > >>>>All the references are highly appreciated. > > >>>> > > >>>>Thanks in advance. > > >>> > > >>>Receiver details for specific impementations are usually kept > > >>>proprietary, so you may not be able to get much info on what is > > >>>actually done, and it probably varies a fair amount from > > >>>implementation to implementation. > > >>> > > >>>There are training sequences built into the GSM frame structure, so > > >>>there are a lot of different tecqniques that can be used to train the > > >>>equalizer. > > >>> > > >>>Eric Jacobsen > > >>>Anchor Hill Communications > > >>>http://www.anchorhill.com > > >>> > > >>I'm pretty sure that the intended "equalization" method for a GSM burst > > is > > >>maximum likelihood sequence estimation. > > >> > > >>-Doug > > > > > >The standards don't specify implementation, just the waveform. > > >Implementers are free to do whatever they wish in the receiver. > > >Sometimes the air interface waveform is designed with some candidate > > >implementation in mind, but one is always free to do their own tricks > > >in the receiver. > > > > > >>_____________________________ > > >>Posted through www.DSPRelated.com > > > > > >Eric Jacobsen > > >Anchor Hill Communications > > >http://www.anchorhill.com > > > > > > > Thanks Doug and Eric. > > > > Do you have any references which I can use to find the implementations ? I > > want to get an accurate number for complexity of channel equalizer and > > estimator algorithms. > > > > _____________________________ > > Posted through www.DSPRelated.comAlthough as others have pointed out GSM standards don't specify receiver implementation, the waveform is tailored for MLSE. Additionally, from first hand experience I know that GSM's equipment conformance specification pushes the theoretical performance bounds of a 16 state MSLE. So while manufacturers may choose their implementations, it's a tall order for suboptimal designs. The following is a good reference in that it contains a thorough treatment of Viterbi equalization for phase modulation in general and GMSK in particular. The book is out of print but if you can get your hands on a used copy I think you'll get a lot of mileage out of it. Raymond Steele, Mobile Radio Communications, IEEE Press, 1992, ISBN 0-7803-1102-7. Some other references: J.C.S. Cheung, R. Steele, "Modified Viterbi equalizer for mobile radio channels having large multi-path delay", Electronics Letters, vol. 25, no. 19, pp. 1309-1311, 14 Sept, 1989. N.S. Hoult, C.A. Dace, A.P. Cheer, "Implementation of an equaliser for the GSM system", Proc. of the 5th Int. Conf. on Radio Receivers Associated Systems, Cambridge, U.K., 24-26 July 1990. R.D'Avella, L. Moreno, M. Sant'Agostino, "An adaptive MLSE receiver for TDMA digital mobile radio", IEEE Journal on Selected Areas in Communications, vol. 7, no. 1, pp. 122-129, Jan, 1989.

Reply by ●March 21, 20142014-03-21

>On Tuesday, March 18, 2014 9:06:05 PM UTC-4, Dan25 wrote: >> >On Tue, 18 Mar 2014 13:33:59 -0500, "DougB" <60916@dsprelated> wrote: >>=20 >> > >>=20 >> >>>On Tue, 18 Mar 2014 02:51:09 -0500, "Dan25" <98432@dsprelated>wrote:>>=20 >> >>> >>=20 >> >>>>Hi All, >>=20 >> >>>> >>=20 >> >>>>I need some specific information on channel equalizerimplementations>>=20 >> of >>=20 >> >>>>practical GSM receivers. I assume time domain equalizers are usedin>>=20 >> GSM >>=20 >> >>>>phones, but I would like to the equalizer algorithms and training >>=20 >> >>>>algorithms and convergence algorithms used by them.=20 >>=20 >> >>>> >>=20 >> >>>>I highly appreciate if anyone can share his/her experience on this >>=20 >> >>regard. >>=20 >> >>>>All the references are highly appreciated. >>=20 >> >>>> >>=20 >> >>>>Thanks in advance. =20 >>=20 >> >>> >>=20 >> >>>Receiver details for specific impementations are usually kept >>=20 >> >>>proprietary, so you may not be able to get much info on what is >>=20 >> >>>actually done, and it probably varies a fair amount from >>=20 >> >>>implementation to implementation. >>=20 >> >>> >>=20 >> >>>There are training sequences built into the GSM frame structure, so >>=20 >> >>>there are a lot of different tecqniques that can be used to trainthe>>=20 >> >>>equalizer. >>=20 >> >>> >>=20 >> >>>Eric Jacobsen >>=20 >> >>>Anchor Hill Communications >>=20 >> >>>http://www.anchorhill.com >>=20 >> >>> >>=20 >> >>I'm pretty sure that the intended "equalization" method for a GSMburst>>=20 >> is >>=20 >> >>maximum likelihood sequence estimation. >>=20 >> >> >>=20 >> >>-Doug =20 >>=20 >> > >>=20 >> >The standards don't specify implementation, just the waveform. >>=20 >> >Implementers are free to do whatever they wish in the receiver. >>=20 >> >Sometimes the air interface waveform is designed with some candidate >>=20 >> >implementation in mind, but one is always free to do their own tricks >>=20 >> >in the receiver. >>=20 >> > >>=20 >> >>_____________________________ =09 >>=20 >> >>Posted through www.DSPRelated.com >>=20 >> > >>=20 >> >Eric Jacobsen >>=20 >> >Anchor Hill Communications >>=20 >> >http://www.anchorhill.com >>=20 >> > >>=20 >>=20 >>=20 >> Thanks Doug and Eric. >>=20 >>=20 >>=20 >> Do you have any references which I can use to find the implementations ?=>I >>=20 >> want to get an accurate number for complexity of channel equalizer and >>=20 >> estimator algorithms. =20 >>=20 >>=20 >>=20 >> _____________________________ =09 >>=20 >> Posted through www.DSPRelated.com > >Although as others have pointed out GSM standards don't specify receiverim=>plementation, the waveform is tailored for MLSE. Additionally, from first=>hand experience I know that GSM's equipment conformance specificationpushe=>s the theoretical performance bounds of a 16 state MSLE. So whilemanufact=>urers may choose their implementations, it's a tall order for suboptimalde=>signs. > >The following is a good reference in that it contains a thorough treatment=>of Viterbi equalization for phase modulation in general and GMSK inparticu=>lar. The book is out of print but if you can get your hands on a usedcopy=> I think you'll get a lot of mileage out of it. > >Raymond Steele, Mobile Radio Communications, IEEE Press, 1992, ISBN0-7803-=>1102-7. > >Some other references: > >J.C.S. Cheung, R. Steele, "Modified Viterbi equalizer for mobile radiochan=>nels having large multi-path delay", Electronics Letters, vol. 25, no. 19,=>pp. 1309-1311, 14 Sept, 1989. > >N.S. Hoult, C.A. Dace, A.P. Cheer, "Implementation of an equaliser for the=>GSM system", Proc. of the 5th Int. Conf. on Radio Receivers AssociatedSyst=>ems, Cambridge, U.K., 24-26 July 1990. > >R.D'Avella, L. Moreno, M. Sant'Agostino, "An adaptive MLSE receiver forTDM=>A digital mobile radio", IEEE Journal on Selected Areas in Communications,=>vol. 7, no. 1, pp. 122-129, Jan, 1989. > >Thanks very much. Its very useful. _____________________________ Posted through www.DSPRelated.com