Hi all,
Did acquisition and tracking with pilot channel sharing the same
process in CDMA2000? the acquisition using xcorr find the coarse delay,but
how does tracking action?
Plan to using 8x oversampling,then fed the stream to a digital matched
filter to find best one from the eight. But really have no idea with the
tracking process, do i need to using xcorr again when tracking? or pass the
eight stream to the digital matched filter to find the best one?
when using 256bit DMF, case chip by chip input, tracking will cause the
stream chosen vary frequency; case 256 size buffer,then block by block
input, tracking will introduce a certain mount of delay. How should i do.
Wish your idea and thanks a lot.
B. R.
Laron
Difference between CDMA pilot channel acquistion and tracking
Started by ●February 26, 2010
Reply by ●February 26, 20102010-02-26
On Feb 26, 3:50=A0am, "Laron" <jason.pi...@inbox.com> wrote:> Hi all, > > =A0 =A0 Did acquisition and tracking with pilot channel sharing the same > process in CDMA2000? the acquisition using xcorr find the coarse delay,bu=t> how does tracking action? > =A0 =A0 Plan to using 8x oversampling,then fed the stream to a digital ma=tched> filter to find best one from the eight. But really have no idea with the > tracking process, do i need to using xcorr again when tracking? or pass t=he> eight stream to the digital matched filter to find the best one? > when using 256bit DMF, case chip by chip input, tracking will cause the > stream chosen vary frequency; case 256 size buffer,then block by block > input, tracking will introduce a certain mount of delay. How should i do. > > Wish your idea and thanks a lot. > > B. R. > Laron =A0 =A0The cross-correlation will need to run continuously, so that you get a new peak for each repetition of of the shortcode. John
Reply by ●February 27, 20102010-02-27
>On Feb 26, 3:50=A0am, "Laron" <jason.pi...@inbox.com> wrote: >> Hi all, >> >> =A0 =A0 Did acquisition and tracking with pilot channel sharing thesame>> process in CDMA2000? the acquisition using xcorr find the coarsedelay,bu=>t >> how does tracking action? >> =A0 =A0 Plan to using 8x oversampling,then fed the stream to a digitalma=>tched >> filter to find best one from the eight. But really have no idea withthe>> tracking process, do i need to using xcorr again when tracking? or passt=>he >> eight stream to the digital matched filter to find the best one? >> when using 256bit DMF, case chip by chip input, tracking will cause the >> stream chosen vary frequency; case 256 size buffer,then block by block >> input, tracking will introduce a certain mount of delay. How should ido.>> >> Wish your idea and thanks a lot. >> >> B. R. >> Laron =A0 =A0 > >The cross-correlation will need to run continuously, so that you get a >new peak for each repetition of of the shortcode. > >JohnThe 32768 xcorr will take a certain long time, should we all use the 32768 size xcorr during both acquisition and tracking, this will introduce certain amount of delay. Another question is when everytime xcorr, we get a new delay, then shall we shift the local generated pn sequence or shift the input data to align with local sequence when despreading? Thanks. B. R. Laron
Reply by ●February 27, 20102010-02-27
On Feb 27, 7:00�pm, "Laron" <jason.pi...@inbox.com> wrote:> >On Feb 26, 3:50=A0am, "Laron" <jason.pi...@inbox.com> wrote: > >> Hi all, > > >> =A0 =A0 Did acquisition and tracking with pilot channel sharing the > same > >> process in CDMA2000? the acquisition using xcorr find the coarse > delay,bu= > >t > >> how does tracking action? > >> =A0 =A0 Plan to using 8x oversampling,then fed the stream to a digital > ma= > >tched > >> filter to find best one from the eight. But really have no idea with > the > >> tracking process, do i need to using xcorr again when tracking? or pass > t= > >he > >> eight stream to the digital matched filter to find the best one? > >> when using 256bit DMF, case chip by chip input, tracking will cause the > >> stream chosen vary frequency; case 256 size buffer,then block by block > >> input, tracking will introduce a certain mount of delay. How should i > do. > > >> Wish your idea and thanks a lot. > > >> B. R. > >> Laron =A0 =A0 > > >The cross-correlation will need to run continuously, so that you get a > >new peak for each repetition of of the shortcode. > > >John > > The 32768 xcorr will take a certain long time, should we all use the 32768 > size xcorr during both acquisition and tracking, this will introduce > certain amount of delay. > � Another question is when everytime xcorr, we get a new delay, then shall > we shift the local generated pn sequence or shift the input data to align > with local sequence when despreading? > > Thanks. > B. R. > LaronFind the XC peak location and then thin off 32678 input samples (those that went into the XC) starting from the one at the peak location and striding by whatever your samples per chip is. Now you have a complex 32k vector that is aligned with the shortcode. You can get complex data symbols as sum(input x conj(sc * w64)) where sc is the shortcode, w64 is the walsh code, and input is your 32k vector. The sum is computed over blocks of N inputs depending on the symbol repetition. N might be 64 (no repetition, one symbol per walsh sequence) or 256 (one symbol per four walsh sequences). So you get a new symbol for every N symbols in the 32k inputs. Now comes the part you asked about earlier. You need to multiply these symbols by conj(pilot) to remove the phase & frequency offset. Pilot is just w0, so you can just compute a pilot symbol for every data symbol. HTH, John
Reply by ●February 28, 20102010-02-28
>On Feb 27, 7:00=A0pm, "Laron" <jason.pi...@inbox.com> wrote: >> >On Feb 26, 3:50=3DA0am, "Laron" <jason.pi...@inbox.com> wrote: >> >> Hi all, >> >> >> =3DA0 =3DA0 Did acquisition and tracking with pilot channel sharingth=>e >> same >> >> process in CDMA2000? the acquisition using xcorr find the coarse >> delay,bu=3D >> >t >> >> how does tracking action? >> >> =3DA0 =3DA0 Plan to using 8x oversampling,then fed the stream to adig=>ital >> ma=3D >> >tched >> >> filter to find best one from the eight. But really have no idea with >> the >> >> tracking process, do i need to using xcorr again when tracking? orpas=>s >> t=3D >> >he >> >> eight stream to the digital matched filter to find the best one? >> >> when using 256bit DMF, case chip by chip input, tracking will causeth=>e >> >> stream chosen vary frequency; case 256 size buffer,then block byblock>> >> input, tracking will introduce a certain mount of delay. How shouldi>> do. >> >> >> Wish your idea and thanks a lot. >> >> >> B. R. >> >> Laron =3DA0 =3DA0 >> >> >The cross-correlation will need to run continuously, so that you get a >> >new peak for each repetition of of the shortcode. >> >> >John >> >> The 32768 xcorr will take a certain long time, should we all use the3276=>8 >> size xcorr during both acquisition and tracking, this will introduce >> certain amount of delay. >> =A0 Another question is when everytime xcorr, we get a new delay, thensh=>all >> we shift the local generated pn sequence or shift the input data toalign>> with local sequence when despreading? >> >> Thanks. >> B. R. >> Laron > >Find the XC peak location and then thin off 32678 input samples (those >that went into the XC) starting from the one at the peak location and >striding by whatever your samples per chip is. Now you have a complex >32k vector that is aligned with the shortcode. > >You can get complex data symbols as sum(input x conj(sc * w64)) where >sc is the shortcode, w64 is the walsh code, and input is your 32k >vector. The sum is computed over blocks of N inputs depending on the >symbol repetition. N might be 64 (no repetition, one symbol per walsh >sequence) or 256 (one symbol per four walsh sequences). So you get a >new symbol for every N symbols in the 32k inputs. > >Now comes the part you asked about earlier. You need to multiply these >symbols by conj(pilot) to remove the phase & frequency offset. Pilot >is just w0, so you can just compute a pilot symbol for every data >symbol. > >HTH, > >JohnHi John That's very very helpful and a large step ahead. still 2 points confused me listed below. 1.Cause the pilot symbols(all zeros) only transmitted on I-channel and i q use different sequence, so how could we make out i channel's imagine part from the complex sampled data? 2.Cause the sync channel's frame head align with 1 after 15 consecutive zeros of short code, so we don't need to do symbol timing and just align walsh code with the short pn sequence, is this right? Thanks B. R. Laron
Reply by ●February 28, 20102010-02-28
On Feb 28, 12:44�am, "Laron" <jason.pi...@inbox.com> wrote:> >On Feb 27, 7:00=A0pm, "Laron" <jason.pi...@inbox.com> wrote: > >> >On Feb 26, 3:50=3DA0am, "Laron" <jason.pi...@inbox.com> wrote: > >> >> Hi all, > > >> >> =3DA0 =3DA0 Did acquisition and tracking with pilot channel sharing > th= > >e > >> same > >> >> process in CDMA2000? the acquisition using xcorr find the coarse > >> delay,bu=3D > >> >t > >> >> how does tracking action? > >> >> =3DA0 =3DA0 Plan to using 8x oversampling,then fed the stream to a > dig= > >ital > >> ma=3D > >> >tched > >> >> filter to find best one from the eight. But really have no idea with > >> the > >> >> tracking process, do i need to using xcorr again when tracking? or > pas= > >s > >> t=3D > >> >he > >> >> eight stream to the digital matched filter to find the best one? > >> >> when using 256bit DMF, case chip by chip input, tracking will cause > th= > >e > >> >> stream chosen vary frequency; case 256 size buffer,then block by > block > >> >> input, tracking will introduce a certain mount of delay. How should > i > >> do. > > >> >> Wish your idea and thanks a lot. > > >> >> B. R. > >> >> Laron =3DA0 =3DA0 > > >> >The cross-correlation will need to run continuously, so that you get a > >> >new peak for each repetition of of the shortcode. > > >> >John > > >> The 32768 xcorr will take a certain long time, should we all use the > 3276= > >8 > >> size xcorr during both acquisition and tracking, this will introduce > >> certain amount of delay. > >> =A0 Another question is when everytime xcorr, we get a new delay, then > sh= > >all > >> we shift the local generated pn sequence or shift the input data to > align > >> with local sequence when despreading? > > >> Thanks. > >> B. R. > >> Laron > > >Find the XC peak location and then thin off 32678 input samples (those > >that went into the XC) starting from the one at the peak location and > >striding by whatever your samples per chip is. Now you have a complex > >32k vector that is aligned with the shortcode. > > >You can get complex data symbols as sum(input x conj(sc * w64)) where > >sc is the shortcode, w64 is the walsh code, and input is your 32k > >vector. The sum is computed over blocks of N inputs depending on the > >symbol repetition. N might be 64 (no repetition, one symbol per walsh > >sequence) or 256 (one symbol per four walsh sequences). So you get a > >new symbol for every N symbols in the 32k inputs. > > >Now comes the part you asked about earlier. You need to multiply these > >symbols by conj(pilot) to remove the phase & frequency offset. Pilot > >is just w0, so you can just compute a pilot symbol for every data > >symbol. > > >HTH, > > >John > > Hi John > That's very very helpful and a large step ahead. still 2 points confused me > listed below. > 1.Cause the pilot symbols(all zeros) only transmitted on I-channel and i q > use different sequence, so how could we make out i channel's imagine part > from the complex sampled data? � > 2.Cause the sync channel's frame head align with 1 after 15 consecutive > zeros of short code, so we don't need to do symbol timing and just align > walsh code with the short pn sequence, is this right? > > Thanks > B. R. > Laron1. The pilot symbol is complex 2. Yes, the symbol timing is taken care of by the xcorr
Reply by ●March 2, 20102010-03-02
>On Feb 28, 12:44=A0am, "Laron" <jason.pi...@inbox.com> wrote: >> >On Feb 27, 7:00=3DA0pm, "Laron" <jason.pi...@inbox.com> wrote: >> >> >On Feb 26, 3:50=3D3DA0am, "Laron" <jason.pi...@inbox.com> wrote: >> >> >> Hi all, >> >> >> >> =3D3DA0 =3D3DA0 Did acquisition and tracking with pilot channelsha=>ring >> th=3D >> >e >> >> same >> >> >> process in CDMA2000? the acquisition using xcorr find the coarse >> >> delay,bu=3D3D >> >> >t >> >> >> how does tracking action? >> >> >> =3D3DA0 =3D3DA0 Plan to using 8x oversampling,then fed the streamt=>o a >> dig=3D >> >ital >> >> ma=3D3D >> >> >tched >> >> >> filter to find best one from the eight. But really have no ideawit=>h >> >> the >> >> >> tracking process, do i need to using xcorr again when tracking?or>> pas=3D >> >s >> >> t=3D3D >> >> >he >> >> >> eight stream to the digital matched filter to find the best one? >> >> >> when using 256bit DMF, case chip by chip input, tracking willcause>> th=3D >> >e >> >> >> stream chosen vary frequency; case 256 size buffer,then block by >> block >> >> >> input, tracking will introduce a certain mount of delay. Howshould>> i >> >> do. >> >> >> >> Wish your idea and thanks a lot. >> >> >> >> B. R. >> >> >> Laron =3D3DA0 =3D3DA0 >> >> >> >The cross-correlation will need to run continuously, so that you get=>a >> >> >new peak for each repetition of of the shortcode. >> >> >> >John >> >> >> The 32768 xcorr will take a certain long time, should we all use the >> 3276=3D >> >8 >> >> size xcorr during both acquisition and tracking, this will introduce >> >> certain amount of delay. >> >> =3DA0 Another question is when everytime xcorr, we get a new delay,th=>en >> sh=3D >> >all >> >> we shift the local generated pn sequence or shift the input data to >> align >> >> with local sequence when despreading? >> >> >> Thanks. >> >> B. R. >> >> Laron >> >> >Find the XC peak location and then thin off 32678 input samples (those >> >that went into the XC) starting from the one at the peak location and >> >striding by whatever your samples per chip is. Now you have a complex >> >32k vector that is aligned with the shortcode. >> >> >You can get complex data symbols as sum(input x conj(sc * w64)) where >> >sc is the shortcode, w64 is the walsh code, and input is your 32k >> >vector. The sum is computed over blocks of N inputs depending on the >> >symbol repetition. N might be 64 (no repetition, one symbol per walsh >> >sequence) or 256 (one symbol per four walsh sequences). So you get a >> >new symbol for every N symbols in the 32k inputs. >> >> >Now comes the part you asked about earlier. You need to multiply these >> >symbols by conj(pilot) to remove the phase & frequency offset. Pilot >> >is just w0, so you can just compute a pilot symbol for every data >> >symbol. >> >> >HTH, >> >> >John >> >> Hi John >> That's very very helpful and a large step ahead. still 2 points confused=>me >> listed below. >> 1.Cause the pilot symbols(all zeros) only transmitted on I-channel and i=>q >> use different sequence, so how could we make out i channel's imaginepart>> from the complex sampled data? =A0 >> 2.Cause the sync channel's frame head align with 1 after 15 consecutive >> zeros of short code, so we don't need to do symbol timing and justalign>> walsh code with the short pn sequence, is this right? >> >> Thanks >> B. R. >> Laron > >1. The pilot symbol is complex >2. Yes, the symbol timing is taken care of by the xcorr >As far as I understood, after the pilot acquisition, a digital-delay loop (DLL) should be used to track the pilot by correcting the on-time pilot with the 1/2 chip early and 1/2 chip late pilot.
Reply by ●March 3, 20102010-03-03
On Mar 2, 1:11�pm, "Frank_os" <spw...@gmail.com> wrote:> >On Feb 28, 12:44=A0am, "Laron" <jason.pi...@inbox.com> wrote: > >> >On Feb 27, 7:00=3DA0pm, "Laron" <jason.pi...@inbox.com> wrote: > >> >> >On Feb 26, 3:50=3D3DA0am, "Laron" <jason.pi...@inbox.com> wrote: > >> >> >> Hi all, > > >> >> >> =3D3DA0 =3D3DA0 Did acquisition and tracking with pilot channel > sha= > >ring > >> th=3D > >> >e > >> >> same > >> >> >> process in CDMA2000? the acquisition using xcorr find the coarse > >> >> delay,bu=3D3D > >> >> >t > >> >> >> how does tracking action? > >> >> >> =3D3DA0 =3D3DA0 Plan to using 8x oversampling,then fed the stream > t= > >o a > >> dig=3D > >> >ital > >> >> ma=3D3D > >> >> >tched > >> >> >> filter to find best one from the eight. But really have no idea > wit= > >h > >> >> the > >> >> >> tracking process, do i need to using xcorr again when tracking? > or > >> pas=3D > >> >s > >> >> t=3D3D > >> >> >he > >> >> >> eight stream to the digital matched filter to find the best one? > >> >> >> when using 256bit DMF, case chip by chip input, tracking will > cause > >> th=3D > >> >e > >> >> >> stream chosen vary frequency; case 256 size buffer,then block by > >> block > >> >> >> input, tracking will introduce a certain mount of delay. How > should > >> i > >> >> do. > > >> >> >> Wish your idea and thanks a lot. > > >> >> >> B. R. > >> >> >> Laron =3D3DA0 =3D3DA0 > > >> >> >The cross-correlation will need to run continuously, so that you get > = > >a > >> >> >new peak for each repetition of of the shortcode. > > >> >> >John > > >> >> The 32768 xcorr will take a certain long time, should we all use the > >> 3276=3D > >> >8 > >> >> size xcorr during both acquisition and tracking, this will introduce > >> >> certain amount of delay. > >> >> =3DA0 Another question is when everytime xcorr, we get a new delay, > th= > >en > >> sh=3D > >> >all > >> >> we shift the local generated pn sequence or shift the input data to > >> align > >> >> with local sequence when despreading? > > >> >> Thanks. > >> >> B. R. > >> >> Laron > > >> >Find the XC peak location and then thin off 32678 input samples (those > >> >that went into the XC) starting from the one at the peak location and > >> >striding by whatever your samples per chip is. Now you have a complex > >> >32k vector that is aligned with the shortcode. > > >> >You can get complex data symbols as sum(input x conj(sc * w64)) where > >> >sc is the shortcode, w64 is the walsh code, and input is your 32k > >> >vector. The sum is computed over blocks of N inputs depending on the > >> >symbol repetition. N might be 64 (no repetition, one symbol per walsh > >> >sequence) or 256 (one symbol per four walsh sequences). So you get a > >> >new symbol for every N symbols in the 32k inputs. > > >> >Now comes the part you asked about earlier. You need to multiply these > >> >symbols by conj(pilot) to remove the phase & frequency offset. Pilot > >> >is just w0, so you can just compute a pilot symbol for every data > >> >symbol. > > >> >HTH, > > >> >John > > >> Hi John > >> That's very very helpful and a large step ahead. still 2 points confused > = > >me > >> listed below. > >> 1.Cause the pilot symbols(all zeros) only transmitted on I-channel and i > = > >q > >> use different sequence, so how could we make out i channel's imagine > part > >> from the complex sampled data? =A0 > >> 2.Cause the sync channel's frame head align with 1 after 15 consecutive > >> zeros of short code, so we don't need to do symbol timing and just > align > >> walsh code with the short pn sequence, is this right? > > >> Thanks > >> B. R. > >> Laron > > >1. The pilot symbol is complex > >2. Yes, the symbol timing is taken care of by the xcorr > > As far as I understood, after the �pilot acquisition, a digital-delay loop > (DLL) should be used to track the pilot by correcting the on-time pilot > with the 1/2 chip early and 1/2 chip late pilot.By doing the XC at multiple samples/chip (I believe the OP mentioned 8) you effectively have the early and late signals in the sidelobes of the XC peak. John
Reply by ●March 4, 20102010-03-04
>On Mar 2, 1:11=A0pm, "Frank_os" <spw...@gmail.com> wrote: >> >On Feb 28, 12:44=3DA0am, "Laron" <jason.pi...@inbox.com> wrote: >> >> >On Feb 27, 7:00=3D3DA0pm, "Laron" <jason.pi...@inbox.com> wrote: >> >> >> >On Feb 26, 3:50=3D3D3DA0am, "Laron" <jason.pi...@inbox.com>wrote:>> >> >> >> Hi all, >> >> >> >> >> =3D3D3DA0 =3D3D3DA0 Did acquisition and tracking with pilotchan=>nel >> sha=3D >> >ring >> >> th=3D3D >> >> >e >> >> >> same >> >> >> >> process in CDMA2000? the acquisition using xcorr find thecoarse>> >> >> delay,bu=3D3D3D >> >> >> >t >> >> >> >> how does tracking action? >> >> >> >> =3D3D3DA0 =3D3D3DA0 Plan to using 8x oversampling,then fed thes=>tream >> t=3D >> >o a >> >> dig=3D3D >> >> >ital >> >> >> ma=3D3D3D >> >> >> >tched >> >> >> >> filter to find best one from the eight. But really have noidea>> wit=3D >> >h >> >> >> the >> >> >> >> tracking process, do i need to using xcorr again whentracking?>> or >> >> pas=3D3D >> >> >s >> >> >> t=3D3D3D >> >> >> >he >> >> >> >> eight stream to the digital matched filter to find the bestone?>> >> >> >> when using 256bit DMF, case chip by chip input, tracking will >> cause >> >> th=3D3D >> >> >e >> >> >> >> stream chosen vary frequency; case 256 size buffer,then blockby>> >> block >> >> >> >> input, tracking will introduce a certain mount of delay. How >> should >> >> i >> >> >> do. >> >> >> >> >> Wish your idea and thanks a lot. >> >> >> >> >> B. R. >> >> >> >> Laron =3D3D3DA0 =3D3D3DA0 >> >> >> >> >The cross-correlation will need to run continuously, so that youg=>et >> =3D >> >a >> >> >> >new peak for each repetition of of the shortcode. >> >> >> >> >John >> >> >> >> The 32768 xcorr will take a certain long time, should we all useth=>e >> >> 3276=3D3D >> >> >8 >> >> >> size xcorr during both acquisition and tracking, this willintroduc=>e >> >> >> certain amount of delay. >> >> >> =3D3DA0 Another question is when everytime xcorr, we get a newdela=>y, >> th=3D >> >en >> >> sh=3D3D >> >> >all >> >> >> we shift the local generated pn sequence or shift the input datato>> >> align >> >> >> with local sequence when despreading? >> >> >> >> Thanks. >> >> >> B. R. >> >> >> Laron >> >> >> >Find the XC peak location and then thin off 32678 input samples(thos=>e >> >> >that went into the XC) starting from the one at the peak locationand>> >> >striding by whatever your samples per chip is. Now you have acomplex>> >> >32k vector that is aligned with the shortcode. >> >> >> >You can get complex data symbols as sum(input x conj(sc * w64))where>> >> >sc is the shortcode, w64 is the walsh code, and input is your 32k >> >> >vector. The sum is computed over blocks of N inputs depending onthe>> >> >symbol repetition. N might be 64 (no repetition, one symbol perwalsh>> >> >sequence) or 256 (one symbol per four walsh sequences). So you geta>> >> >new symbol for every N symbols in the 32k inputs. >> >> >> >Now comes the part you asked about earlier. You need to multiplythes=>e >> >> >symbols by conj(pilot) to remove the phase & frequency offset.Pilot>> >> >is just w0, so you can just compute a pilot symbol for every data >> >> >symbol. >> >> >> >HTH, >> >> >> >John >> >> >> Hi John >> >> That's very very helpful and a large step ahead. still 2 pointsconfus=>ed >> =3D >> >me >> >> listed below. >> >> 1.Cause the pilot symbols(all zeros) only transmitted on I-channeland=> i >> =3D >> >q >> >> use different sequence, so how could we make out i channel's imagine >> part >> >> from the complex sampled data? =3DA0 >> >> 2.Cause the sync channel's frame head align with 1 after 15consecutiv=>e >> >> zeros of short code, so we don't need to do symbol timing and just >> align >> >> walsh code with the short pn sequence, is this right? >> >> >> Thanks >> >> B. R. >> >> Laron >> >> >1. The pilot symbol is complex >> >2. Yes, the symbol timing is taken care of by the xcorr >> >> As far as I understood, after the =A0pilot acquisition, a digital-delayl=>oop >> (DLL) should be used to track the pilot by correcting the on-time pilot >> with the 1/2 chip early and 1/2 chip late pilot. > >By doing the XC at multiple samples/chip (I believe the OP mentioned >8) you effectively have the early and late signals in the sidelobes of >the XC peak. > >JohnThe resolution should be 1/8 chip time i think. And John, can you do me a favor and leave your email-address to me? just in case when be trapped. my email address is warmfreetm@gmail.com, leave me message if you wish. :) Thanks B.R. Laron
Reply by ●March 4, 20102010-03-04
>>On Mar 2, 1:11=A0pm, "Frank_os" <spw...@gmail.com> wrote: >>> >On Feb 28, 12:44=3DA0am, "Laron" <jason.pi...@inbox.com> wrote: >>> >> >On Feb 27, 7:00=3D3DA0pm, "Laron" <jason.pi...@inbox.com> wrote: >>> >> >> >On Feb 26, 3:50=3D3D3DA0am, "Laron" <jason.pi...@inbox.com> >wrote: >>> >> >> >> Hi all, >>> >>> >> >> >> =3D3D3DA0 =3D3D3DA0 Did acquisition and tracking with pilot >chan= >>nel >>> sha=3D >>> >ring >>> >> th=3D3D >>> >> >e >>> >> >> same >>> >> >> >> process in CDMA2000? the acquisition using xcorr find the >coarse >>> >> >> delay,bu=3D3D3D >>> >> >> >t >>> >> >> >> how does tracking action? >>> >> >> >> =3D3D3DA0 =3D3D3DA0 Plan to using 8x oversampling,then fedthe>s= >>tream >>> t=3D >>> >o a >>> >> dig=3D3D >>> >> >ital >>> >> >> ma=3D3D3D >>> >> >> >tched >>> >> >> >> filter to find best one from the eight. But really have no >idea >>> wit=3D >>> >h >>> >> >> the >>> >> >> >> tracking process, do i need to using xcorr again when >tracking? >>> or >>> >> pas=3D3D >>> >> >s >>> >> >> t=3D3D3D >>> >> >> >he >>> >> >> >> eight stream to the digital matched filter to find the best >one? >>> >> >> >> when using 256bit DMF, case chip by chip input, tracking will >>> cause >>> >> th=3D3D >>> >> >e >>> >> >> >> stream chosen vary frequency; case 256 size buffer,then block >by >>> >> block >>> >> >> >> input, tracking will introduce a certain mount of delay. How >>> should >>> >> i >>> >> >> do. >>> >>> >> >> >> Wish your idea and thanks a lot. >>> >>> >> >> >> B. R. >>> >> >> >> Laron =3D3D3DA0 =3D3D3DA0 >>> >>> >> >> >The cross-correlation will need to run continuously, so thatyou>g= >>et >>> =3D >>> >a >>> >> >> >new peak for each repetition of of the shortcode. >>> >>> >> >> >John >>> >>> >> >> The 32768 xcorr will take a certain long time, should we all use >th= >>e >>> >> 3276=3D3D >>> >> >8 >>> >> >> size xcorr during both acquisition and tracking, this will >introduc= >>e >>> >> >> certain amount of delay. >>> >> >> =3D3DA0 Another question is when everytime xcorr, we get a new >dela= >>y, >>> th=3D >>> >en >>> >> sh=3D3D >>> >> >all >>> >> >> we shift the local generated pn sequence or shift the input data >to >>> >> align >>> >> >> with local sequence when despreading? >>> >>> >> >> Thanks. >>> >> >> B. R. >>> >> >> Laron >>> >>> >> >Find the XC peak location and then thin off 32678 input samples >(thos= >>e >>> >> >that went into the XC) starting from the one at the peak location >and >>> >> >striding by whatever your samples per chip is. Now you have a >complex >>> >> >32k vector that is aligned with the shortcode. >>> >>> >> >You can get complex data symbols as sum(input x conj(sc * w64)) >where >>> >> >sc is the shortcode, w64 is the walsh code, and input is your 32k >>> >> >vector. The sum is computed over blocks of N inputs depending on >the >>> >> >symbol repetition. N might be 64 (no repetition, one symbol per >walsh >>> >> >sequence) or 256 (one symbol per four walsh sequences). So you get >a >>> >> >new symbol for every N symbols in the 32k inputs. >>> >>> >> >Now comes the part you asked about earlier. You need to multiply >thes= >>e >>> >> >symbols by conj(pilot) to remove the phase & frequency offset. >Pilot >>> >> >is just w0, so you can just compute a pilot symbol for every data >>> >> >symbol. >>> >>> >> >HTH, >>> >>> >> >John >>> >>> >> Hi John >>> >> That's very very helpful and a large step ahead. still 2 points >confus= >>ed >>> =3D >>> >me >>> >> listed below. >>> >> 1.Cause the pilot symbols(all zeros) only transmitted on I-channel >and= >> i >>> =3D >>> >q >>> >> use different sequence, so how could we make out i channel'simagine>>> part >>> >> from the complex sampled data? =3DA0 >>> >> 2.Cause the sync channel's frame head align with 1 after 15 >consecutiv= >>e >>> >> zeros of short code, so we don't need to do symbol timing and just >>> align >>> >> walsh code with the short pn sequence, is this right? >>> >>> >> Thanks >>> >> B. R. >>> >> Laron >>> >>> >1. The pilot symbol is complex >>> >2. Yes, the symbol timing is taken care of by the xcorr >>> >>> As far as I understood, after the =A0pilot acquisition, adigital-delay>l= >>oop >>> (DLL) should be used to track the pilot by correcting the on-timepilot>>> with the 1/2 chip early and 1/2 chip late pilot. >> >>By doing the XC at multiple samples/chip (I believe the OP mentioned >>8) you effectively have the early and late signals in the sidelobes of >>the XC peak. >> >>John > >The resolution should be 1/8 chip time i think. > >And John, can you do me a favor and leave your email-address to me? justin>case when be trapped. >my email address is warmfreetm@gmail.com, leave me message if you wish.:)> > >Thanks >B.R. >LaronAnother question is how to choose rake receiver's finger delay. One or tow fixed chips or variable, is there any principle? I've seen in some implementation that the fingers' delay could be quite different like 0(finger0) 14(f1) 30(f2) etc. so could we dynamic adjust these delay by some algorithm? Thanks. B.R. Laron.
