Note: Descriptions are shown in the official language in which they were submitted.
WO93/23K3 ~ 8~9 PCI~US93/~)3692
METHOD A~D CIRC~lT FOR ~ELECIING TUN~G OF A RADIO
RECEIVER
B~ound of the l~ventio~
Th~ pre~t i~v~n~on rehteB ge~ y to radio recei~er8,
aDd, more par~cul~ly, to a me~hod for selec~ng t~ of a radio
~er to a ~eque~cy cba~l of a ~et of f~quen~ nels, and
as~o~ated cucui~y for implemen~g BUCh
0 A ca~munication Bylltem i~ operative to transmit
bet~reen t~o or Dlore locations, and in~des, at a
m~imu~, a tra~smi~er and a reoei~er interoonnected by a
co~unication channel. A xadio communication ~y~tem i8 a
co~mu licatio~ ~tem in ~i~ih the commu~ica~ion ~hannel
a compnse~ a radio ~equen~r ~ihanne~ wherein ~he radio f~equen~y
~el i~ defi~ ed by a raDge of frequencies of ~e communication
~p~ctn~. '
The tn~tter ~i~h form~ a por~on of 1 he radio
oommunicatio~ s~tem i~ludes C~Ni~ for conver~g the
~formation ~to a fonn ~uitable for ~n~ion th~of upon a radio
frequ~y channel. Su~h circuitry in~ludes modulation circuitr~r wbich
~onn~ a p~e88 refe~ed to a~ modulation. In ~u~h a proce~s, the
mation ~v~ich i8 to be tra~mitted i8 imprc~ed upon a radio
freque~:y electromagnetic ~a~e, com~os~ly seferred to a~ ~ canier
2S sig~l. ~e re~tant 8ig~al iB COmmODIy referred to a~ a modulated
sigDal. 8u~ lmltant Sig~ is also refensd to as a communication
dgDal a~ the modubted oignal include~ the i~fom~ation ~vhich i8 to be
commm~icat~d bet~ee~ the t~n~tter and 1 be recei~er.
Variou~ modulation scheme~ are kno~n for impressing 1 he
i~formation upon ~he camer dg~al to form ~hereby the communication
al. For iDstance, amplitude modulation, fireque~cy mod~ation,
pha~e modulation, and combinations thereof are all modulation
WO 93/23963 PCI/US93/036g?--`
809 - 2 - ~
sc~emes by whi~h information may be impressed upon a ca~ner wa~re to
form the communication dgnal.
Radio communication systems are advantageous in that no
ph~ical ~ection iB required bet~reen ~he transmitter a~d the
s r~ er; once the informaffon ~i~ is mod~lated to form a modulated
dg~al, the modlila~d dgual ma~r be tr-D~mitted o~rer large dista~6.
~ dditioDally, numorous modulated 8~ may be
simultaI~eoudy tra~mitted at different frequencies of the
~lectromagnetic f~quenc~r spectrm. T~n~don of oomm~nication
~o d~Dals on ~equency channels deftned upon oertain ~equency bands of
~ie ele*~netic f~eque~cy ~um are regulated by regulatory
bodie6.
- A t~o-way, radio communica'don system i6 a radio
communication ~gstem, dmilar to the radio commun~cation system
5 _ibed, but vhich further pes~ts both ~muni~ion of
infilrmation to a location, and tr~n~mi~ion of information ~om that
locati. Each location of su~h a t.~ay, radio communication sy~tem
o~ntains bo1 h a t~mitter and a rec~er. The t~n~itter and the
receiver pogitioned at a single location typically compn~e a unit referred
20 to as a radio t~iver, or, more simply, a t~sceiver.
A odlular commu~ica~on ~ystem is a tgpe of t~vay radio
communicatiQn o~rstem in ~rhich communication i8 permitted ~nth a
radio tr~cdver positiQnod at any location Wit~iD a geographic area
enc4mpa~s~d by the c~llular communication sy~tem.
2~ A oellular co~nu~ication ~bm i8 created by positioD~g
a plur~ity of fi~ed~ite radio tr~ dver6, referred to as ba~e statio~, at
~paoed-apart locations thro~ghout the goographic area.
I~e base station6 are CoD~ct~ to a conventioJ~ vireline, telephQnic
network. Each base statiQn ha6 a~ ia~d there~nth a porliQn of the
30 geographic area locatsd pronmate to each Qf such ba~e stations. Such
portions are refe~ed to as oeL~6. The plurality of cc118, each defi~ed by
corre~pondiDg onos of the base ~tations of 1 he plurality of base station6
together def~ne the co~rerage area of the cellular communication 6y6tem~
A radio tran~ rer, referred to ~ a eellular
36 communication system as 8 radiotelephone, positioned at any location
wit~in the co verage area of the cellular communication system i6 able to
WO 93~23963 PCI /US93/03692
-3~ 1 12809
communicate ~n~h a user of the conventional, wireline, telepho~ic
net~rork by ~ray of a balle station. CommuI~ica1ion signil6 ge~erated by
~he radioteaephoIIe are tran~nitted to a btue ~ on, and then, by way of
~he oonventio~, vrireline, teaephoDic network to a desired ~nreliI~e
5 location to e~ec~ate t~b~ telephoDic ~mmunication t~ere~ith.
TelephoDic an~catio~ may al80 be ef~ectuatsd ~nth the
radiotdeph~e UpO~I ~itiation at ~e wi~liDe location.
A co~ve~tion~ protocol o$ operation of mo~ llular
oommumcation 8~ determines to which of the ~e statio~s of the
to c~ular oDmmu~cation system the radiotelephone t~ mits, and
, c~mmu~cation ~ig~. Elfectuation of ~n~s~ion of
commuDica~on 8ig~ by a ba~e station to a radiotelephone i8 referred
to a~ a "oommm~ication do~n-link;" effectuation of tra~smission of
commuJ~ication ~ b~ a raaotelepho~le i~ referred to a
15 "communication up-link."
The f~ uen~ ~ha~els ~to ~hich the ~equency band
allocatod for cellular c~mmu~cation are dinted are further divided into
control ~ha~el~ and traffic ~haDnels. In oon~entional, cellular
c~mmunication ~bnu, ~he cont~ol ~el8 and traffic c~els are
20 defiDed to be of differing frequencie6. In ll~t~m8 U~i~g time dinsion
mul1iple~ te~que~, the control and t~c chaDnel~ may alBO be
deSned to be of ~imilar frequency channels, but defined to be of
as~imilar time ~lots there n.
The control cha~nel6 are allocated for transmio~ion of
25 I:ommu~cation ~gnals, here referred to as ca~tr~l ~ignals, by the ba~e
stations. The radiotelephones are operative to scan the contr~l channel6
(both during po~ver~g on of the radiotdephone and penodically dunng
operation thereof~. The power levels of the ~ s traDu~tted upon the
oontrol ~annels are au:erb.ined, and responsive to su~ moasured
30 values, t~e radîoteJephone att~mpts to aso~rtain the i~forma~don content
of the control dgnal generated upon one of the control cba~els. During
~uch stage of sig~ transmi~ion, if the information content of the
WO 93/23963 PCI`/US93/0369~
2~ ~. 2809
co~trol ~ignal tr~tted upon 1 he selected control c~annel may be
a~certailled, a~ e infon~latio~ conte~t of t he co~trol ~ignal
tl~Umitted UpO~I BU~h co~trol chaJ~n~ m~ets pre-defi~ed cntena, a
communicatioIl do~n-linl~ is e~ectuated. The ~rer circuit"~ of the
ra~otelep~e re~ tuned to ~e ~lected control ~hannel. In
e~eDce, the ra~otdep~oDe tune~in to t}~e selected cont~l ~hannel, and
~sten~" to ~e i~ ation bdDg tr_itted thereupon. Su~:h
opoTa~on of ~e N~otdophone is ~o~e~ refe~ed to a~ "c~mpiIlg" of
the radiotelep~one, and once a commumcation do~ k i8 effectuated
o bet~veen a base statioD aDd the ra~otslep~one, ~he radiotelephone i6
some~mes refe~d to a~ g "camped-to a base 6tation (or cell site)."
Once the co~u ~ication down-li~k ha6 been effectuated
between the ~diot~lephone and a base statian, rec~ver cim~try of t he
ra~otelepho~ may be pouered-down, ~d o~ly periodically powered-on
5 again in a desired duty ~rcle. During penod~ in whic}l the receiver
circuit~r is agam po~er~d, the information content of the control sig~nal
1~ tted upo~ ffu ~docbd coD~l ~haDnel (i.e., the control cbannel
to ubich the radiotsaepho~e is "campedn) iB monitored. (It i8 noted that,
at t mes, contr~il dgnale may also be 1;ransmitted UpOI~ the ~affic
- 20 ~hannel. Su~ih control ~ig~ are typically trl-n~nitted, however, after
a co~nunication li~ ha~ already been effeceuated between the
radiotelephone a~d the ba~e datio~)
Because the receiver cim~itrg i~ powered-on oDly
periodically, eIlergy con~umption of such circuitry is mi~mized once a
communication down-liDk has been effectuated uith a base station.
When a call is beil~g made to the radiotelephone, the
iDfQnnation coDtent of the control ~ dire~ the radiotelephone to
certain oIIes o the traffic ~hannels uhereupon voice com~nunication
may 1 hen commence.
Because of the increased populanty of use of such cellulsr
communication system6, ma~y of such c~lular communication
~, at times, are operated at full capacity. That is to say, at times,
wo 93/23963 Pcr/us93/03692
-s~ 21l2809
e~ available traffic ~hannsl of ths ~qusn~y bant allocatsd for
oeJlular commu~ca1;io~ i8 uset. To ~de acces6 to greater numbers
of wors of cuch o~Jlular ca~nu~uca~on ~, schemes ha~re bsen
de~elaped to u~lize mo~ ef~icien'dy ~he f~quency bands aJlocated for
s su~ use.
In par~cular, to ~c~e capaci~ llu~r communication
~bnu are b~ ~trod~d ~}~ich utilize more efficient modula~ion
~mes. Modulation u~heme~ ~bich malce u~e of ~s~tely-encoted
~farma~a~ ~ m~ efficiell~ly u~lize th~ ~equency ~iha~u~16
o allocatod for ~llular ~icatio~u. Henoe, u~e of ~u~h modulation
~heme~ ~t ~ater ~ o u~ to utilize ~imultsn~ 1y a
olilltllar oomm~ca'doll ~ Such modlalation s~hemes genera~e
c~uDicatio~ dg~alB ~rhich are am~able to tru~s~ion utili~ng
the ti~ multipl~iDe t~ques noted briefly hereinabo~re.
~s C~Ye~OD~, 0~1~ commu~cation ~tem~ and
~llubr ca~muD~ca~o~ ~ of incr --ed capac~ty are ge~rally
~compa'dble ~t~. Tbat~ to ~ay, ra~otdepho~os opera~ve m a -~
con~oDal~ c~ular clmuD~cation ~ystem are t op~rative ~ a
odlular ca~unumca~on ~tem of iDN~-ed capac~ty. (W~ile dual
20 mode ~adiotdepu~ are operative i~ dther o the cellu~
co~unication ~u, ~uch dual mode radiotelephones ~ilude dual
cu~uit~r por~o~s, ~ith one circi~y portion operative ~ one 8~8tem and
another cucuitry portion op~rative in the other 8~tem, ~h~eby one or
the other of the Ci~Nit~ portions is oporativo dopending upn the
2s oommuDication sy~bm in rhich the rad;iotelephone is to be operated.)
l~o or more cellular commuDicatio~ ~ystems are
some~mes i~talled in cerbin geog~aphical areas. For instanoe, both
con~ention~ alld i~ capacity, cellular communicatian bd~i
are installed in certain geographicel areas ~idi~g cdlular coverage
30 in either of ~uch ~. ln ol~er geographical aroa6, oDlg
co~rentioDal, c~illular commuDication qr8t~ are i~talled. (A
geographic a~a may, a~alogously, have only a~ increased-capacity
- wo 93/23g63 ~ 1 1 2 8 0 9 - 6 - PCI /US93/03697 ~
system in~talled.) A~d, ~ dill other ~eographical a~afi, no cellular
c~mmunicatio~ tems ue in~talled.
~s ted prenoudy, ~rhen the ~er circuitry of a
radiotel~pho~e i8 powered o l, the radiotdephone aear~es control
S ~hannels to detect 1 be pre~eDee of a co~trol oien~ transmitted
t~po~ Wh~ ~he ~diotalephone i~ ~tioned in a geographic area
Dot hanng odlular co~rage, su~ ~ear~ o~ e co~trol cha~lel6 doe8
t result ~n the detec~o~ of a ~igDal tsan~mitted by any balle sta'do~.
, a rs~otclephone anu~ to be operati~e in a
0 partic~ar one of the ocllular oommu~ on qn~tems (i.e., a
ca~ve~ti~al, oellular commu~cation system~ or a cellulu
commmucation ~ystom of increlued ca~ty3, but po~itioned at a
location ha~g ce~ular coverage by another, but incompatible, cellular
oommmncatio~ ~ystem al~o does Dot det~ t~e prese~ce of a oontrol
dgnal t~umitted up~ the d~fi~ed o~ntrol ~bannels of t;he cellular
oommmucatio~ sgstem in ~hich the radiotelephone iB operative.
Bocau~e the ~equenc~r band~ of ca~e~iioDal c~llular
commu~cations ~ and ceDular commu~ication ~y~tems of
increa~ed capu:ity are operative in ~equency bands hav~g o~erlappiDg
- 20 ~oqueDcies, a radiotdepho~e, uhe~ he control cJIannels,
may detect 1~ pre~ence oa control dgnal t~tted by the other of
the cellular commu~ication sydems. However, becau~e ~e sy~tems are
incompatible, the information content of such a detscted ~ignal cannot
be _tdned by ~uch radiotelephone.
- , ~any radiotelephono~ are ~o~ucted to be operat~d by
battery power supplie6. Becau~e battes~r power supplie6 are of fi~ite
energy storage capacity, ~uch radiotelephones are operative for ODly a
limited period of ~me. 8e~bing by the radiotelephone of the control
cb-nn~ for control 8ig~al8 tralumitted thereupon ~quire8 po~ve~Dg of
~e ~adiotelephone. The radiot~le~hone sear~ ot o~y for the
pre~ce of dgnals upon the co~trol ~nn~, but, additionally, al~o to
deteTmine the infonnation content of any detected 8igDal.
WO~93/23963 PCI/US93/03692
-7- ~112809
If the radioblephone i~ posi~oned at a location hav~g no
o~llular coverage, or hanDg c~llular oov~e of an ~compatible
o~ular commu~ on ~ystom, oontinued ~ar~g by t~e
rsdiotelephone o~1 he o~ntrol ~ha~els re~ults in deplet;ion of t~e stored
e~r o ~e batto~y po~or ~upply ~rbi~h po~vers 'she radiot~lephone.
Su~ oo~ued ~ Nreore, can re~ult in se~rere limitation in
the operatio~ penod athe radiot~ep~e to commu~ucate
tbe~oug~, an ~re amount of ~tored energy is depleted
uur~ing the eontrol e~a~el~.
0 What i8 Deoded, ~erefore, is means for limiting con1inual
~g by a ~adiotd~oDo o~ co~trol ~ha~lelB ~rhen a
co~icatio~ li~ eant be e~tabli~hed ~ith a ba~e station.
Swllm~ of the I~vention
T~e pro~t invontion, ac~y, advantageously
provide~ a m~hod, aDd a~o~ated c~ uitry, for overcom~g the
limitations o~he i~ting art.
The present invention fur~er advantageously pronde6
meaI~s for li~ting contiIIual ~ing by a radiotelephone of control
B when a eomm~eation liDI~ cannot be established ~nth a ba~e
station.
The pre~ent invention includes further ad~antage6 and
featuros, the detdb of wbieh ~ill become more apparent byqeeding the
detailed descnption of the pr~e~ed enibodiments herei~belo~v.
In a~ with the pre~ent invention, a method, and
a~sociated cir~Nit for impl~menting ~uch, for ~electiDg tUD3~g of tuDing
~itry of a radio roo~er to a frequency ~hannel of a set of frequency
nels defiIIed upon a frequen~r band i8 disclo~ed. Ea~h frequen~y
~hannel of ~e set of frequen~r ~hannels is ~uitable for t~nsmission
~hereupon of a communication ~ignal ~n~tted b~ a ~ssn~U;er of a
group of remotely-positionod tranu~tters. The tu~i~ Qrcuit~ of the
radio re~eiver i6 tuned to oa~h frequen~ nel of the set of ~quen~y
W O 93/23963 PC~r/US93/03692-_
2112809 - 8 -
nel~ defined upon ~he ~equen~y band. Power leve~s of
oommu~catio~ ignal6 t~tted upon indindual one~ of the
f~equenc~r ~nn~ of the ~et of frequen~ ha~els are measured.
E~quen~y ~hannels upon ~ h communications Illg~Qal6 of mea6ur~d
s po~ver level~ beyond a predet~rm~ned mi~imum po~er level are selected
to fwm a first ~et of f~eque~ ~nnel6. A d~tenni~ on is made
~er a ~ommu~icatio~ may be efectuated bet~re~ the radio
reoei~er and ~dindual ones of the tran~mitter which l~nilmits
commu~ication d gDalB upon the f~equen~y channels of the first subset
o of f~quen~r ~s. Tu~iDg of the tu~i~g ~it~r of the radio
reooi~r to a ~oq~ cha~el upo~ ~rhich a communication ~igDal is
mitted by a tr~tter to which a commu~ication li~k with the
radio receiver msy be e~ectuated is selected when such communication
IjD1C is possible.
1~ :
Bnef Desdption of the Dra~nngs
q~ne present invention wDl be better understood when read
20 in light of ~e aocompan~g dra~i~gs in which
~ IG. 1 i8 a par~ hematic, par~al block dia~ram of a
odlular communication sysbm in which the method and circuit of the
prefemd embod~ent of the present invention i8 operati~
EIG~ 2-IiB a ~hematic ~epreu~tation of a portion of a
2~ frequency band allocated for cellular ccmmunications;
l~G. ~II is a ~hematic representation of a sulgle
f~equenc~ cha~el illu~tratislg time ~lot~ defined ther~upon a~ utilized
in a 'dme di~nsion multiplesiDg technique;
- FIG. 3 i8 a logical block di-gram of a radio recei~rer
30 i~uding the ~rcuit of the prefe~d e~bodiment of the present
~ve~t~on;
WO 93/23963 PCI`/US93/03692
9 ~11 280~
PIG. 4~ a ~ta~on of t~e relationship between the
po~rer lev~ of c~trol dg~ m~ured d~in~ operation of the
preferred embodim~t of t~e pre~e~t ~vention aDd a d~ally-
establi~hed ~oue floor den~ed therefirom;
EIG. 4-II u a representation of the r~latio~hip between the .
po lrer le~ o control dg-lals me~Dd d~ operati~ of 1 he
p~d embodim~t o 1~ present ~ve~tion and an abso~ute- ~alued
Doise floor,
~G. ~ u a r~ntation illustratiDg t~e relatio~ip
o betw~ the po~ver le~l o~ a previoudy-mea~ured sigDal a~d the po~ver
level of ~ ~d upa~ easurem~t ~eroo, a com~on of su~h
po~rer lo-eb is u~zed dunDg operatio~ of 1 he p~erred embodiment o
1 he pr~e~t inventio~
FIG. 6 i~ a logical flow di-gmm of an algont}~m ~odying
~e me1~od ~ffle prd~ed ~bodiment of 1he p~tiDvs~tio~;
FIG. 7 i~ a logical flo~v diagram ~ng 1~e ms1~ tsps of
a preferrod embo~nt of ~he p~t invon~on; a~d
~IG. 8 is a blo~ di-gr~ o a radio tran~o~iver ~cauding
t~e circuitry of the prefe~d embodiment of the preseDt i~reDtio~.
Des~ riptio~ of ~e Prefe~ed Embodiment~
.
RefemDg fir~t to ~e s~hematic illustratio~ of FIG. 1, a
cellular communication q~tem, ~ferr~d to generally by referenoe
25 nu~l lQ0, i8 8howm ~ me~tio~ed herei~ e, a odlular
oommuni`cation ~tem i~ ~rmed by po~itio~Dg numerous ba~e ~tation6
at ~paoed-apart lo~tio~ roughout a geographical ar~a. .8u~ ba~e
~u are illdicated in ~IG. 1 by poq~ts 104, 108, 112, 116, 120, 122, 126,
and 1~ ile dght base ~tatio~s are illustrated in the fig~re, it is to be
30 understood, of course, that a ~ypical ce~lular communication s~tem,
representsd by c~llular cammuDication system 100, i8 conventionally
comp~ised of siguifioantly greater numbers of base stalio~s.
WO 93/23963 PCI/US93/0369~
21~ 2809 -10-
Ea~h base ~ta'do~ 130 co~ta~ ~try ~tting
~n~ion of commu~ca~on ~als tnn~mitted by the ba~e ~ on
to a plur~ity ora~otdephon~ ~rhe~ BU~ radiot~lepho~e~ are
oned at lo~ n~ the vicu~it~r of re~pec~re ones of t~e ba~e
S ~ oD~, a~d to ~e ccmmuDica~ dgDals ~n~tted by ~uch
plurality o~radiotelepho~.
Eu~hba~ d;a~ 104-130 i~ coupled to a conven~onal,
~ine, t~lephonic ~et~rorlc. Su~ co~ec~o~ u repre~ented in the
fig~ by ~e 134 ~r~ e ~tation 130 and ~vireJine net~vork
0 1~8. Co~a~ bet~e~ ~irdine net~rork 138 a id other oIIe~ of the
ba~ ~ oDs 104-126 may be similar~y ~ho~.
The pod~o~g of ~ of the base statio~ 104 130 form~g
o~ular commuDicatio~ ~D~m 100 i~ ly ~lecbd to en~ure that at
le~t a~e ba~o ~tatio~ u po~itioned to reosive a oo~mu~ca1io~ ~igDal
1s-n~tt~d by a ra~otd~a~e po~i~oned at any location throughout
tho g o~raphical area ~ 8~ 100, ther~by defining 1 he
odlular o~ area o~e system. That i~ to ~ay, at lea~ e ba~e
cta~ 104-130 mu t be ~ in the ~miudo~ ge of a
radiotelepl~e po~itioned at ally such lo~a~on ~roughout the
g~ ical aroa. (Becau~e tbe m~imum dgnal B~glh, and hence,
~ don range, of a ~al 1n-n~tted by a base ~tation
i~ typically groater than the m~imum dgnal ~ngth, and
co~spondil~g ~um tr-n~io~ raDge, of a ~ignal generated by
a radiotelepho~e, the ~um tran~s~ion range of a ~igDal
generated by a radiotelepho~e i8 a p~ma~ filctor whi~ih mu~t be
coD~idered ~he~ podtio~g the ba~e statio~ of the c~lular
commumcatioII ~y~tem.)
B_e of the ~paced~ ature of ~e po~itioDi~g of the
ba~e ~tio~, pcr~o~s of the geographical area throughout whi~ baE~e
~tatia~s 104-130 are located are a~so~ated ~ indindual ones of the
ba~e ctatioDs. P~ioIu of the geograpbical area pro~imate to ea~h of the
spaced-apart ba~e ~ ioDs 104-130 deSne "cel18" ~rhi~h are represented
wo g3/23963 2 1 1 2 8 o 9 PCI/US93/03692
.
m tbe figure by area~ 144, 148, 152, 166, 160, 162, 166, and 170. Cell6 14
170 tog~er fo m 1~e geograp~ic~ area alld def~ne the ooverage area
encompa~d by odlular oommunica1;ion ~ystem 100. A radiot~lephone
po~iffoned ~ ou~dsrie~ of a~y of 1h~ odl8 144-170 of s~tem lO0
ma~ t~umit, aDd ~re, modulated ~ignals to, and from, at lea~t one
~munica1ia~ ~tem 100 iB re~re~tative of a
co~ventio~al, ~llular oommu~ica~on a~tem or a odlulsr
commumcatio~ ~tem of iDc~ed capacity.
0 ~ also men~m~ed p~nou~ly, ~e general protocol of
oporaffoD of imffa~ of commmucation in a c~llular commu~ica~on
qctsm m~ol~a detec~oD by a radiotelephone of commu~cation aignala,
here ref~d to aa contral ~a, tn~tted by ~ano~ onea of the
baae ~tation~ ranoua all_ of the oontrol ~hamlel8 defi~ed Ul t he
oommumc~tion ~atom Ea~ ba~e atatio~ of ~he cdlular
oo~mucation ~ m tra control 8ig~ on predefined control
cb~nd~ to ide~tify ~e preso~oe of su~ base ~ta~oD, a~d thereby to
~ffect~ate a co~u~ieatia~ do~-link ~i1~ a radiotelephone once the
radiot~epho~ e il~fo~maiion co~ts~t of the control dgDal
~_t~ed upa~ a ~lected coDtrol ~ el. (Agai~, ~rben t~
dind~ multiple~ t~niquea are utilized, coDtsol and tsaffic
~els may be defined at similar frequencies, but in diasimilar time
~lots.)
Once a cammu- ication down~ been effectuated
bet~ree~ the radiotelepb~ne a~d a base station, por~o~s of ~e r~rer
~itry of the radiotelepholle may be powered-do~, to be re-po~ered
~herea~er i~ a de~red duty c~e to ascertain, dur~g re~ultant ~odic
~tor~6, ~he iDfo~atio~ co~t~t of the coDt~ol ~al tr~mi~d upo~
When a call is made to the radiot~lephone, the il~formation
c~ntent (i.e., the data) of the control ~i~al instruct~ the radiotelephone
to be tuned t~ par~cular traffic ~ els defined upon the ~llular
WO 93~23963 æ 1 ~ 2 8 0 9 PCI /US93/0369?~
communica~ion ~y~tem to penmt two~way communication between the
radiotelepho~ d the ba~ tatio~ Othenvi~e, portio~ of t~e recei~er
circuit~r of the radiotelephone i8 powered-do~m according to 1 he de~ired
du~ c~ile.
Ho~ever, whe~ ~he n~diotdepho~le i6 po~itioned beyond 1 he
area of a o~llular oommumca~on ~ tem, a ~earch of the
oo~l cbanneb of the oommu~oation ~tem doe~ ~ot result ~ the
detec~on of a dgnal pen~ttiDg e~ectua~on of a comml~nication li~
For in~t~oe, a ~otelepho~e, i~dicated in t~e figure by radiotelephone
0 174, u po~itioned be~ond the oellular coverage area of cellular
oommmucatian ~m 100. A ~ h of the oontrol ~ihannels by the
radiotelephone ~ positianed begond the odl~ar coverage area doe~
not re~ult in effec~ation of a oommu~cation li~ wi~ any of the
~als tra~ttodb~ y oft~e base ~tation6 104-1~0 of ~tem 100.
Repeated ~bing of ea~h of the control ~ha~els othe
oommunication ~ to detect 1he pre~ence of a dgnal tran~itted
t~pon, a~d ~e informa~ t o~ any ~ detected dgnal, i6
both time~ and eD~r con~umpti~e. AB a radioteaophone i8,
in many i~tano~s, powered by a batte~r po~ver ~upply, energy
oo~nption of the radiot~lephone iB des red to be limited to ~na~ze
the p~od of ~iiity of tbe ~diot~lephone ~nth ~ batte~ po~ver
BUpply.
AB alBo me~tio~ed previou~ly, due to the introdu~tion of
ceJlular oommunication ~y~temB of im:rea~d capacity, cell llar
2~ co~erage area~ ro or more c~lular ooD~mullicatian ~ystems may
o~erhp b;ot~ ~aphically ~nd in f~equency. In EIG. 1, points 204 and
208 ropre~t ba~e stations of a ~econd ceJlular commuDication system,
uld c~8 214 aDd 218, ~how~ ~ hat~h, rq~ ent covcrago aroas of t~e
ceals of the seco~d cellular ca~u~icatio~ ~tem. Shaded area 222
so repre~ents o~erlappi~g, goographically, of co~erage area~ of 1 he two
odlular co~uDication qd~m8. A radiot~lephone located in area 222
iB able to detect control ~al8 tra~mit~d by both base station 122 of
~vo 93~23963 PCI /US93/03692
-13- ~11280Y
~y~tem 100, and ba~e statiaD 208 of ~he ~ecoDd communica~on ~ystem.
Du~g a sear~ of oo~t~ nels of 1~e cellular communication
q~stem in ~ i~ the radiot~l~phone i~ opera~i~e, ~he control ~ignal
~erated by a ba~e ~tation of the other of 1~e commm~ication system~
may be detected b3r ~e ~adiotel~pho~e. A communication do~-link
he base ~ a~ of ~ othor c~ communication ~y~tem
ca~ot be effectuated a~ the t~o oommunicatian ~rstems are
~compa1ible. The debctod ~ontrol si~al o~ ~h control chamlel
~hould, accordin~y, be i~d by the radiotelepho~le.
0 Additio~ally, when ~e radiotelephoqle iB iDitially po~itioned
bo~ond ttle oeJlular co~e~age area othe commumcation ~y~tem in
~hich ~e radiotel~phone is op~a1i~e, (here, for pU~pO8 of illust~atioIl,
o~ular communication ~stem 100), but iB subsequently relocated to be
~ithin the co~erage aroa of the c~llular communication ~tcm, the
~adiotdephane mu8t be d~e to detect the pres~e of oo~trol dg~
tr_t~ed upon the oontral ~nneb of the conunuDication systcm
o-loe po~itioned ~ntbin the co~e area thereof. Howe~rer, again, such
oontin~al ~ng of the oontrol cha~els of the commmi~cation
system to detect the ~oe of oontrol sig~als thereupo~l caD be quite
en~ cons~mpti~e.
FIG. 2-I is a cchematic representation of a firequency band,
~ned to generally by r~erence num~l 300, allo~ated for c~llular
oom~nuDication~. E~quency band 300 i~ divided into numerou~
&equency cha~nels, ~omo of ~rhich are designated to be control
2~ cba~hels, here de~igDated by Dl, D2, . . . D", and tr~c ch~el~ Vl,
V2, V3, . . . Vn. Upon po~er~g-on of a radiotelephooe, ~he general
p~otocol of operation of iDitiation of ~sbment of a oom~numcatio~
li~ ~vith a ba~e cta~ , the ra~otelephone ~ear~es es~h of ~he oontrol
~ nels defiDed upon fr~queDc~r ba~d 300.
FIG. 2-lI is a s~hematic represent~on of a ~ngle
fhquenoy ¢b~el, here designatsd by referenoe numeral ~06, and the
time ~lotc defined thereupon o~er a pe~iod of time. Frequency cba~el
WO 93/23963 PCI'/US93/0369?----
2 1128 09
306 represent~ 1;ime ~ defined upon a ~gle f~equen~r cha~nel whe~
time-di~ril~ion m~ le~g t~hniques are u1ilized. Frequen~y channel
306 defines a plur~ity o~'dme ~lots ~hereupo~ UsiDg the designations of
~IG. 2-I, time ~lots Vl ~oug~ Vn are defi~d to be traffic chaD~els,
aDd ot~er ~me ilot~ Dl ~hrough DD.are d~ to be control ChaD~ 8.
E IG6. 2~ d 2-II u~lize ~imilar de~ation6, a~ the
method and cir~Nit of ~e preferred embodim~ts of tl~e pre~ent
~vention are op~le to ~ oontr~l ~nnd~ defi~ed eit~er
oonventi~ally or in a time-division multiplesed ~tem.
0 l~iDg ci~Nit~y of the receiver por~on of ~uch
r~diotclephone t~es tbe ra~otd~phone to e~ of the control ~hannel6
Dl, D2, . . . Dn to detect ~he pr~ of oontrol ~8 t~ mitted UpO~l
any of the control ~a~els. The p~er levels of any detected control
~igDals o~ a~y of the ctr~l ctuDn~ are me-~uTed, and a
oommusicatio~ li~ i8 attemptet to be efectuated ~nth the tra~itter
~i~ih tealumits the detected sigDal of greatest po~ver le~el (by
~rtd~ the i~fo~atio~ content of su~h detected sigDal).
A commul~ication down~ k may be effectuat~d with such
tramlmitter ~ben the information content of the control ~igDal iB
~rblinabae by the radiotelephone. Tbat is to sa~, ~vhen an attempt i6
made to fft~ a communicatioII do~linlc ~vith a base ~tation of an
_patible oellular communication system, the infonnation content of
su~ co~trol sigDal ca~ot be ascertai~ed by the radiot~lepbo~e. Such
data sigD~ ~hould be y~ored by the ~otelepho~e m s~uent
searche~ of the oo~trol ~a~el ~rhen atte~nptulg to e~ectuate a
comm~cation IjD~ e of the ba~e stations of a oeJlular
commu~ication sy8km.
It ~ w ted that the po~er le~ of 01gDal8 detected by
receiver circuitry may be qui~ldy and efficie~'dy (i.e., ~ith little e~lergy
SO co~umption) determined, ~rherea6 determiDation of the iDfonnation
content of an enooded dgnal detect~d by the reoei~er typically require6
opera1ion of ~gnal proce~ung circuitry. 8uch circuitry require6
93/23963 PCl /US93/03692
,~j 2112809
re~ati~ely dgnifics~t amountB of ~eagy for operation. T~e pre~ent
in~ention adnrantageoudlr minimizes the ti~es ~ wbi~ ~u~
proo~ing circ~itry mu~t be operated.
Tuming ~e~t to the logical blo~k diagram of FIG. 3, a
circuit~ reerred to gener~ly by refere~oe nu~neral 400 comprised of t~e
dements encompas~sd bq the block Isho~ in hat~, of the preferred
nbodiment of t~e pr~sent invention iB ~lO~ Circu;it 400,
illw~ated in FIG. 3, fi~s a postion of a radio r~iver, referred to
g~dly b~ reference m~meral 406. Redio reoei~r 406 may, for
~ample, compri~e the receiver ~itry portion of a radio tran~ceiver,
w~ as a radiotelephone, ~rati~e in a cellular communication
~tem.
Radio recei~er 406 iB operative to search predefined control
~hannels, su~h as caDtrol channe~s Dl-Dn sho~m in FIG. 2-I or FIG. 2-
Il to detect the presenoe of coDtrol dgnal~ mitted upon i~di~idual
o~es o~the control et~.
CoDtrol l~ha~els, of whi~h lin J.12 are indicaiive,
t~mitted by ~itters, su~ ~ansmitter 416, are detected by
ante~na 418 of receiver 406. ~als represe~tative othe signt~ls
det~d by a~teDna 418 are generated on li le 420 and suppJied to
progr~m~le t~down~version circuit~r 422. Cira~it~ 422
tune6 t he rece~ver to certain fhquenc~ nel6, here initially the
control ~hannels, respondve to ~als supplied 1 hereto on lines 436.
Circui~y 422 generates signal~ on line 448 ~p~ta~e of
the C~! l~ dB ~nt}lin par~cular ones of ~he f~eque~r cha~nels to
whi~ cuit~ 422 tl~nes the receiver 406. The ~ generat~d on
line 448 are supplied to demodulator 458 and ~1 streDg~ mea~uring
Qrcuit~y 468. Demodulator 458 g~nerates a demodulated dgDal on line
464 ~rhi~h i8 wpplied to decoder 470. Deooder 470 generates ~als on
line 476 whi~h are applied to processiDg devioe 482. Deooder 470 i8
fur~er operative to generate a deooded dg~l on line 486 ~bi~ih i6
coupled to transducer 488, su~h as a spealcer.
wo 93~23g63 2 1 12 g O 9 16 PCI`/US93/03692_
Sig~al str~ me~in~ circ~g 468 generate~ a ugnal
o~ line 492 ~},i~ u oou~ed to an ~put of p~oce~ device 482 to
~u~ply ~bereby proo~g de~ioe 482 wi1~ ma'don r~lating to the
power level of the d~ g~eratod on liIIe 448. ~8 ~he signal generated
oll line 448 i~ ~dica1ive of`a ~al det~d by antenna 418, the leve~ of
1~e ~al geD~ated o~ o 492 ~ ~imila~ly indicative o1he power le~rel
oftbs ~al dete~dby ~teD~a 418.
M~os~y d~t 496 i~ f~er il~u~ated in 1 he figure
amnN:ted to pn~ing d~oe 482 by line~ 498.
o I~l opera~on, ra~o reoeiver 406 f~rst ~earc~e~ each c~el
of a predeSenninea ~ot cf ~s oo~trol ~iha~el~ defined upon a
commuDica~on ~tem to detect the presence of control ~ign~s
~umitt~ thereup~
Proo~g donoe 482 geDerates dg~ on li~e 436 to cause
t~iDg of circ~i~ 422 to ea~ o the oont~ hannels in sequence.
W~ t~e reo~er 406 ~ tuDed to ea~ of the control channel6, 11ig~lal6
iDdic~tive of ~e det~ed dg~l o~ ~e respec~e ones of ~e contr~l
cb~ are g~qd by circuitr~r 422 on line 448. Sig~al dreng~
m_iDg circ~utr~r 468 D~ea ~e amplitudes of the ~8
- 20 ge~rated o~ line 448 and gcDerates 1~18 on line 492 indica~ve of~uch po~er levels. P~o~Dg denoe 482 stor~s such mea~ured value~
iII memo~y elemont 496. P~oo~d~g device 482 is operative to comlate
1 he measured po~er 1Ovea8 aIld the frequency chaDnels on which such
~als are tr n~tted.
2s - Onoe the power l~els of the data dg~als Dmitted upon
the ~OU8 control ch~els have beeD measured, proces~g device 482
i8 operativ~ to dete~ne ~hether an attempt should be made to
oBt~h a commu~ication do~-link ~nth a tran~tter ~rhich
~n~ts a coDtro~ al upo~ one of the co~ltrol ~ nels.
In order to m~ke such desermination, processor 482 form~; a
fir~t ~ubset of control cha~els of the set of control Cha~l8. The
control cha~nels of ~rhi~ the first sub~et i~ c~mpri~ed are selected
~VO 93/23963 21 1 2809 PC~r/US93/03692
- 17 -
re~po~ive to ~e po~ver le~els of ~e control E~ignal8 tsaD~tted
tllereupo~.
In the preferr~d embodimeJlt, oDly co~ ihannel6 upon
~ ih data dg~als having po~er 1~ bey~d either: 1.) a
5 d~ca~y-ed~d "~e floor" level; or 2.) aI~ absolut~valued
Dl~ise floor are u~lected to ~rm ~he ~_B of l~le fir~t ~bset of control
~annel~.
The dy~amically~tabli~h~d noise floor is e~tabli~hed by
oowillg ~e po~rer l~nel~ of`ea~ o~e co~tral dg~ measured by
0 dgDal ~ me~aring ~i~ 468. Tbe n~e floor i~ e~tablished
at a po ver lo~el at a oerbin ~ue above a measured power level of lowest
magDitude.
FIG. 4 I i~ a represe~ta'do~l of ~he d~cally-established
ue floor, do~ignated i~ 1 he figure b~r line ~0. Ea~h a~o~ ~60
5 d~ates a dgnal det~cted ~on a oo~tro~ nel by recei~er ~06 of
~IG. 3. The hoight of ea~ arrow ~60 is iDdicative o t~e power level
t~eof. Li~e ~0 dedgnati~g the id~ca~y~establi~hed noise floor i6
e~li~d at a oe~tdn po~er level, indicated by ~et 570, above t~e
po~er le~el of ~e ~ of ~he lowest power levd, ~ubh dg~al beiDg
20 ~ted b!lr ~e ar~ow 660 positio~d at the ~t-most dde of the
figure. F~Quency cb~ upo~ w~i~h data silEDal~ of power level~
greater t~an this naise floor are selected to fonn the fir~t subset of
co~trol ~ha~s. ~1~e ~ralue of the dy~cally-es~blished, noise
floo~ is dependent upon the measured power le~el ~lues, the ~alue of
25 ~`Doi~e floor 80 established is ~ranable, dependi~g upon the actual,
measured power level6 of the oontrol d gllal6.
The absolute-~ued Doise floor i~ a power level of a ~elected
ma~itude. FIG. ~II i~ a ~tation of the ab~lute-~ralu~d, noise
floor, d~ated in the figure byline 60~ h a~ 610 de~ate~ a
30 dgnal detecbd up a control ~ . The d gDalB repre~ented by
a~Tows 610 oorrespond to 8ig~al8 ~ pre8 ~ t~d by arrow~ ~60 of FIG. 4-I,
and the height~ of each arro~v are indicative of the power level thereof.
WO 93/23963 2 1 1 2 ~ O 9 PCI /US93/03692~
- 18-
E reque~ nel6 upon ~}lich control 8ignalfii of power level6 greater
than 1~ noi~e floor are al~o selected to fo~m ~he first 8ub8et of control
channels.
Hence"n the preerred embodiment, control channel6 are
s ~lected to fon~ the fir~t ~ot acontrol ~ ~ if a oontrol ~Fnal
mitted t~reupon i~ greater ~a~ either ~he dyna~cally-
~i~YI Doi8e floor or the ab~olute ~alued ise floor.
An attempt to ~ctuate a communica~on link ~ a
~_itter ~ ich tr_ts a control dg~ to recei~er 406 i~ made
0 only ~nth traD~tters w}~i~ trans~ts ~ignal6 upon control ~hannel~
ot~ t ~et of ~o~tral ~
A commu~ ation li~ is effectusted oDly ~vhen decoder 470
i~dicates the pr~ce of ~alid iDformation of the c~ntrol ~ignal once
demodulatedby demodulator458, aI~d ~upplied th~reto on line 464. (I~at
is, dieooder 470 generates dgD~ on line 476 wh~n the infoDation-
co~t~t of t~e co~ol ~il tra~tted upon the ~lected control
~ba~el may be a~certai~) The dg~al generated b~ decoder 470 on
~e 476 and ~up~d to an ~put opro~ d~ice 482 indicat~
proper decodiDg of ~e iI~fo~mation c~tent of ~uch a control s~ d,
hence, an i-~dication that a commmYica~on lin~ may be effectuated with
1he tr~tter ~vhich tN~its such a control ~gnal.
If a commumcatioII li~ may not be effectuated ~ith any of
the traD~tt0 w}~ich tr~momit the control 11ignal8 upon the f~equen~y
channeas of w~ first ~bset of f~equency cha~nels, ~e radio receiver
2~ pau~s far a certain time period pnor to again oommenc~g to attempt to
e~tabli~ a commu~ication li~ ~n1 h a tr~munitter. Dur~g 8u~ih time
period; por~ons of the cira~itry of the receiver may be po~rered-down to
li~t energg uulge of the reoeiver 406 du~g su~h per.iod. (For i~utance,
docode~ 470, typically c~sed of a dieital ~gnal prooes~or, may be
po rered-dow~ dunng 8uch ~me period.)
WQg3/23963 _~9_ 21,~28n9PCr/U593/0369Z
In a preferred embodiment, the time period du~iDg which
por~o~ o ~e reoei~rer power do~ the l~r of a fised amount of
~me (e.g., fifl;e~ seoo~d~) and the 1ime p~iod gi~en by t~e equation:
he ~umber of ~quen~r ~ha~lels of t~e fir~t
s sub~et ~ z%
~hore:
TP i~ 1~ ~mo ~od (in ~econd~);
s i~ me penod r~ed to mea~ure t}~e power levels of
the data dgnals tr_it~ed u~on a~y of the control ~ 18;
0 y is tbo ~ r~d, onoe a deciaion has ~ made to
attcmpt to o~ili~h a ~ ication li~c ~i~ ono othe ~e station6,
of cir~ 422 to tmlo reooi~er 406 to a partidsr control ~ha~el; and
Z iB a do~rod duty cy~e of the radio roceiver.
~fter the ~ ponod dun~g wbich the recei~er po~rer~-
do~ ela~, po~r i~ uppliod to a~ ~e circuit component~ of
~he ~r 406 aJ~ o ~ 422 ~ ~ operative to tu~e the
to ~ of ~o cootraa ch~els o~e ~oque~lcy ba~ lhe
~r l~d~ ~ ~ of the dg~ab 1~n~1nittod u~a~ ea~ of ~be
re~e o~o~ o~ the co~trol ~ha~e~ are a~ measured (i.e., re
measured) by c~it 468, ~d dglU-18 i~dicati~re of ~ measured
po~ror le~s aro ~piod o~ line 492 to prooe~ng de~ice 482.
P~g d~i~ 4sa is opera~e to ~re 1he r~mes~ed po~ver
ls of the oo~ol d~ t~Dsmitted UpOD the resp~cti~re ones of
co~trol ~, ~d to com~e su~ asured power.lenl~
nr V~. ~oudy-me~uured po rer lovels of 1 he dgDd8
upon the frequen~y cbaJ~nels of t}le first subset of~equen~;y
c~a~els.
P~S device 482 is operati~ e to fi~n a ~ d ~ubset of
control chaD~els. O~lly contral ~hannel6 upon ~vbich d~ta 8~8
ha~ing power le~ ~bi~h: l.) were previou~ly less thaD the
dgDamically-o~tablished noise floor, and ~rbi~ih, upon re measurement
are a~e BU~h d~Damically e~tabli~hod lloi~e floor, 2.) ~rere previoudy
wo 93/23963 Pcr/us93/036g?--
211 2809 -20- .
lesg ~n ~he absolute-valued noi~e iloor, snt w~i~h, upon r~
n~urement sre ~ove ~ olute~alued noi~e floor; or 3.) eshibit a
~ignificant nse in power le~el (for i~tance, ~ increa~e ill power le~el of
~ deciW~) are ~lec~d to form t he ~han~ls of th~ ~cond ~ et of
5 co~lcha~el~ ~d,acammunication~ attemptedtobe
effectuat~d anl~ ~nth tr n~mitters ~rhi~h t~mt8 ~8 upon
~qu~g dunDeb of ~is ~ecoDd subset. D~ooder 470 i8 again operative
to generate ~ignalll on line 476 to indicate ~rhether a commuDication link
may be effectuated
1 o (It is ted that other methods of ~electing the secoDd ~ et
f ~D eb-nnel~ may al~o be utilized. For iD~t~, in ~ubstitution
for ~tep~ 1.) and 2.) abo~e, colltrol ~a~nea~ upon ~hi~h data dgnal6
ha~iDg po~er le~el~ ~rhich ~vere preniou~ly le~ 1~an both the
d~n~ly e~tabli~d ~oise floor aDd ~he ~ibsolute-valued noi~e floor,
and ~hich, u~on re me~t are abo~re either o~e of the noise
floors may be u'dlized to fonn the ~cond ~ et of co~trol d~
More particul~ly, P~e de~ioe 4sa i~ operative to
dbtenni~e upon whi~h frequency chauneas are ~als which were
previou~ly b~low dther ~the noise floor~--i.e., b~low eit~er ~e
20 d~amically~t~i~ed Dosse floor or t~e absolut~ralued ~ e floor--
a~d rhich as r~measurod, are abo~e the re~cti~e one of tbe ~ue
floor~, or are of a dgDifica-ltly ~a~d mag~itude.
Iine 499 is fur~er ill~trated in the f~gure pro~idi~g a line
for an e~te~ input to prooe~g de~ioe 482 to reset opera~on of
2s receiver 406 at any 1ime. Such a dgnal may be generated, for esample,
by actuation of an actuation ~ h co~ected to line 499.
~ IG. 6 i~ a ~ntation of operation of p~g device
482 to dete~e vrhi~ equen~ ~_ to ~lect to ~n~ the ~econd
sub~t of frequen~ el6. Again, attempts are made to effectuate a
30 co~u~cation li~ ~ith o~ly those I~D~tt~rs ~vhich tramlmit
dgn~ll6 upon oontrol ~hannels of su~h seoond ~ub~et.
~v~ 93/23963 Pc~r~us93Jo3692
8 0 9
HoTizontall~ne 650 represent~ the dy ~ oa~yqestab~shed
nonse ~oor, and ~un~u~ntEllbne 6~;5 represQnts ~he absolute~alued noise
~oor. (It i8 Oed ~hat~he re~ative value4 of~he nonse ~oor~ could al80 be
rerer~ed, ~nzL, ~he ab~w~ute~valued nonse ~oor Dl~y ~ ofa v~ue greater
tbuLl ~he d ~ ct~ly-e~t bi~3~ed no~se ~oor.) hrrow ~Kh6 repreBe~ts a
~4gDE~ tr luLIitted upon a freq~ency c~Eum ~l }u~ yg E~liDit~i~y-
rce~uRIrea pKnverlevelbffu~th ~hat ofD~nse ~ocrs 6~iO Euld ~ 5. (Iti6
noted t~t w isefloor~ 6UUD auua 6~i6 oorse1FKnDa to non~e floor6 5~UD E~d 605
of EIC~s. 4!I and 4~II,rosFffK~iv~ he f ~ ency cbEu~nel upon wb~ch
o ~gDE~ 6~6 i~tran~ritted does ~otforr~ a FKn~ion of~he f~r3tEndb~et of
frequu~lcy ~b~umel~ as the pKnver level of EigD~ 6Uh6, upd~l ~t~
moasurement, ~ benoath 'dhe noise floon.
Ho~vever, after the ~rer F~u~e~ for the time period
det~d ~y 1~e E~ne-Dobd algorithm, E~d the power lev~ of ~he
sig~ t~munitted on ~e ~arious o~es olf ~he co~trol ~ha~els are r~
measured, ~e dgnal generated on t3he ~ame corkr~ el, E~d bhere
~dicatod by a~v 644, d~ ~ }iat~ht i~ abo~e at least o~e of the na~e
floors. 8u~ oo~trol ~ha~el u ~lected to form a co~trol ~hannel of t~he
seco~d ~ulbset of fr~queD~y ~el6. And, a cor~mumcatior~ dow~
- 20 i~ at~ted to be offectllated ~nth a t~tter which trsnsmits a
ooDtrol dgDal ~on a ~lected corltrol ~iha~el of ~he ~cond s~ot of
control ~el~. A control cha~el having a control Big~
mit~ed t3horeupon of significantly ~crea~ed power level~
(irre~ecti~e of whether t!he re-mea~ured value es~eeds a no~e floor) i6
also selected to fosm 1~e ~ nd gub~et of control c~il6. Such a
signal is ~dicated in EIG. ~ by arrow 670, shown in hat~h.
If, after the po~e~ level~ of the data ~igDals 1~nu~t~ed
upon the respective o~es of the co~trol ~ihannels are re-me~red, no
communication down-link can be effectuated, the radio reoeiver 406
again pauses for a 1ime period, and t~be C~Nit~ of t~e reoeiver power6-
do~m once agam. ln a preferred embodiment, the predeterm~d time
WO 93/23963 2 112 8 0 9 2~ PCI /US93/0369?~--
period i8 a 'dme period corresponding to the gr~ater of a fi~ed time
period, or 1 he pre~iou~ly-noted algon~hm.
That is, ~ ~me penod dunng whi~h portions of the
reoeiver po~ver down i~ ~e greater of a fised amouD.t of ~me (e.g., fifl;een
d tbe 1ime ~od given by ~e equatia~:
TP - (s~r ~ the nu~ber of f~equency c~els of the first
~t)) ~ z%
~here:
0 TP is 1he ~me period (in seco~ds);
s is ~he ~me penod required to measure 1 he po~ver levelfi of
~e data d~ls tr_itted upon any of the o~trol cha~nel6;
y i~ the 1ime r~ o~ce a de~sion ha~ made to
attempt to est~Ji~ a o~umcation li~ ~nth one othe ba~e stations,
of ~ 422 to t~ne roooiver ~06 to a par~icular cont~ hannel; and
z is a de~d duty ~:ycae of ~e ~o receiv~r.
With re~¢ence again to EIG. 1, when the radiotelephone is
located bey~d the area of ceal~ar cove~e of oe~ular communication
~tom 100, ~8 taD~t~d by vanous o~es of the base station6 upon
~he co~tr~ll ~neb are beDeath the noue floo¢~. A radiotelepho~e
i~umporatiDg cir~it~ dmi~ar to radio recei~ror 406 ~ not attempt to
e~t~i~ a communication do~n~ nth a~y othe ba~e stations
~n~ttiDg a~y of such ~ignals on any of ~he f~equency ~s~el~.
- Ho~vor, ~he~ the radiot~lephoD~e i~ repo~iioIIed to be loca~ed ~nt}~in
2s the ceJluhr coverage area of celluhr commu- ication ~rstem 100, aDd
~e power le~els of the data dgJ~dB tra~mitted on ~he ~rarious one~ of
~e co~ol ~nn~b by the ba~e stations are re-me~ared, at lea~t one of
the controa dgDtllB ~ill no~ be of a po~er level in escess of the noi~e
aoors or ~vDl be of a dgl~ificantly ulcreasod po~er level. Contr~l
eh~nds upon whic}l such data sigI als ~ D~tted are ~elected to
form the control chann~s o the ~co~d subset of ~que~r channel8,
and an attempt i8 made to efectuate a commul~ication li~k with the base
~,vo 93/23963 . . PCl`/VSg3/03692
-23~ 2809
~ta1ion whi~h transmit~ ~uch ~ al upon one of such control channels.
e radio receiver circui~y power~-down for a predetermined 1ime
pe~iod afl;er a deterniDa~on i~ made that a communica~on link cannot
be e~tabli~ y of t;tle tra~mitter~ w~i~h ~it co~trol
~; llig~lB UpO~I ~ranOUII ones of the contral ~haD~aB, ~nergy usage of the
radio iB n~zed.
Such a prooes~ of ~electi~ ntr~l ~hannels to fo~ e
~econd Bub~et of co~t~l ~a~nel~ i~ repeated, oomm~ation do~-
links are attempted to be e~ectuated, and powe~down of 1~e receiver
o =~ occur~ if no do~m-li~ ca~ be effectuated continuea. After a
~elected ~e penod, su~ a~ ~utes, if a commu~cation down-
li~ ca~ot be effectuated, ~he ~tem ia re-iDitia3ized to dete~e
a first ~ibset of con~ol chan~eas. .
I~inl nest to 1 he logical flow diagram of P IG. 6, an
~ithm, r~ferred to ge~erally b~r reference numeral ¢80,
in~rpora~g 1 he method of ~e prefemd e~odimell~ of t~e p~e~ent
imrention ~ ~ow~ ~t, and as mdicated by bl~ 684, ~he power l~els
of llignals tran~mitted upo~ ea~ of the co~ mea~ured.
The fir~t subset of oontrol channels is fo~ed, as indicated by bloek 688,
- 20 and an attempt i8 made to establish a communication do~vn-link ~vi1~ a
~umitter wl~ich tn~lumits a oontrol ~ignal upo~ one of su~h
channels, as indicated by blo~k 692.
At decision blo~ 696, a detennina1ion i8 made whether a
communication do~n~ k may be efFectuated. If a do~ k may be
2~ effectuated, the yes branch i~ taken to block 700, ~nd the tuni~g
frequency of t~e re~iver tu~ng circuit~r iB ma~tained at 1~e fiequency
of the selected coJlt;rol chan~el. OtherQn~ e no branc}l is ta~e~, 1he
me~ed power levels are saved, as indicated by blo~k 704, and portio~s
of the receiver power-do~ for a 'dme penod, a~. ~dicated by block 708.
After ~e 1ime penod elapses, ~he pOrtiO~16 of the reo~iver
power-on again, and ~he power le~rels of the control ug~d8 tra~lBmit~ted
upon the controi channels are re~mea~.ured, a~. indicated by bloc~ 708.
W093/~3g63 2112 809 24 - pcr/uss3/o36s~
The ~ d ~ et of co~trol ~ha~lB i~ fo~ned, a~ indicated by block
712, and an att~mpt to ~t~h a do~ li~ with a ~mitter which
trlmu~ts a co~trol ~al upon one of ~uch ~annel~ iB made, a6
i~dicated by blo~ 716.
s At deci~ blo~lc 720, a det~~ tion is made whether a
communication do~-li~c may be ~echlated. If a down-link may be
e~ted, t}~e yes b~ i8 ta~ to blo~ 724, and the t~g
~quen~y of t~e ~ver t~ Uit~y i8 ~ cbd at the ~ of
~he ~lected c~tral ~el. O~hennse 1~e ba~h is talcen, t}~e
o II_ed power levels are saved t,o update the st,ored power level6
tho~eby, as il~dicated by bloclc 728, a~d ~e porlions of ~e recei~er power-
down for a 1ime pcriod, as indicated by blo~k 732.
After ~e time period ~lapses, a detenninat,ion i8 made,
iDdicated by hlo~lc 736, a~ to wbether or not al~ estended t~me period l~ince
5 fir~t m~ 1he po~rer le~els of the control 8~ (at blo~k 684) has
1~ If o, ~e ~e~ bra~ iB tal en to blo~ 684, and ~e proces~ i8
repeat~ 0~, ~he no bra~c~ is talcen to b~o~k 768, a~d the power
level~ of the control signals are re-measured.
l~ine nest to the logical flo~ gram of FIG. 7, the
method steps af the p~eerred ~bodiment of the method, referred to
~Iy by ref~oe numeral 750, of the pr~t invention are l;.sted.
Method 7~0 selects t~ of tu~g circuit~r of a rsdio r~ei~er to a
h~ ~hannel of a set of frequency cha~l8 defined upon a
~ band. Eu:h freque~ nel of the set of frequellcy
~ha~els i~ suitable for transmission thereupon a communication
sig~al tbi~t~ed by a tramlmitter of a group of remotely-posi'doned
tr~D~tters.
Eirst, and as ~dicated by block 756, the tu~g circuitry of
the radio receiver i8 tuned to each ~qu~cy ~ nel of the set of
So ~equency cbaDnels defiIled upon the frequency band~
~VQ 93J23963 w 1 1 2 ~ O 9 Pcr/us93/03692
- 2~ -
Ne~ d as indicated by block 762, 1 he power le~rels of
oommu~ication dg~ n~tted upo~ individual one~ of the
~qu~ _~ of the ~et ~ ~uency ~ are mea~ured.
N~t, and a~ indicated by blo~k 768, 1 he f~e~uen~y ~hanrlel6
s upon ~vhi~h cammuDicatio~ dgDal~ are trdn~tted of measured power
lov~ beyond a mi~imum po~or lo~ to ~rm a fir~t ~ et o~firequen~y
N~t, and a~ indioated by blo~lc 774, a deten~n-tio~ iB
made as to ~he~her a commu~icatio~ may be effectuated bet~veen
0 the sa~o ~oo~ver and ~dividual one8 of the tnm~tters whic~
Dt8 commu~icati~ dgDal~ upon the f~equen~y chamlel~ of the
first ~b~et o 1~equ~ channe~.
l~en, ei~er, a~ ~dicated by blo~ks 778 and 782, tun~g of
~he tu~ cu~itry o~e radio reoeiver i~ s~lected to a
5 ~ha~il upo~ ~ich a commu~ication dgnal tr~m~tted by a
~umitter to ~bich a commu~ ica~wl li~ with the radio reoeiver may
be dfe~ated i8 ~elocted, or 1.) ~e t~ ~try a~the radio recei~rer
i~ re tu~ed to ea~h frequ~mcr ~ nel of the ~et of frequency cha~nels,
2.) the po~er levels of the commm~ication 8ig~?i are re-measured, 3.) a
20 ~d sub~et of f~enq ~ha~d8 i8 formed, and 4.) tun~g of the
~adio reoeiver to a *equ~r ~ba~el o~the ~ d ~ et of frequency
cha~els i8 ~lectod ~vhe~ a oommu~catio~ li~ may be effectuated
there~ith.
Eg~ly, t~ to the blo~k di~m of FIG. 8, a radio
25 traD-aiver, d as a radiotelephone, referred to generally by refere~ce
numeral 800, is sho~ Tr~ ceiver 800 inc~ude~ circuit 806,
compri~ tbe eleme~ts ~nthin the blo~ sho~vn in hat~h, of a preferred
_diment of the prose~t ~rentio~. Circuit 806 correspo~d~ to cucuit
400 of FIG. 3. Tbe roooiver portion of radio transceiver 800 is llimilar to
30 radio receiver ~06 sho~ i~ the blo~k diagram of FIG. 3, a~d ~peration
thereof ~1 ~ot agam be de~ibed ~ detail. E~min-tio~ of the receiver
por~ of radio tr~ eiver 800 indi~atss that radio tran~oeiver 800
WO 93/23963 PCl`/US93/0369~-
` 21t2809 -26-
in~udes antenna 818 to wbi~h ~ne 820 ~ oonne~ed forLnterconnec~Dg
ante~na 818 to p~ogr~ible t~do~m oon~er~ion cira~i~ 8æ.
C~x~a~o~ ofcu~N~try822 ~ contro~ed by input d~ upp~ed ~hereto
on ~D~ 836. C~ try 822 generate~ a E~U~ o~ e 848 wk~h is
s coupled to demodulator Qrcui~ 858 a~ld ~al ~treng~ measur~g
cir~i~y 868. Demodl~lator cucuitry 8~8 generate~ a demod~ated
dg~al on li~ 864 w~ i~ ~uppJied to decoder 870.
Dooodbr 870 generat a ~al O~ e 876 w~i~h i8 coupled
to an input op~ing dcvice 882. D~ooder 870 fi~er generste~ a
0 deoodet ~1 on line 886 wbdch is ~uppJied to transducer 888, ~ a
~er. 8ig~al ~ngth mea~un~g cm uit 868 generates a BigD~
~bdch i8 ~upp~d to p~Dg de~ice 482 by ~ay of line 892. Memo~y
e~eme~t 896 8 fi~her coupled to prooes~g t~ice 882, thereby way of
li~ 898, ~ li~e 899 ~de~ bn~ input to ~e proo~ssing
s denoe882.
R~dio ~n~ 800 i~ fi~rther sho~n to inc~ude a tranu~it
por~o~ han~g oo~nponent portia~ ~how~ gener~lly to ~ilude a
tr~ducer, su~ as a ~dcrophone, 908, en~oder 912, modulator 916, and
progr_le ~g-up~ er~on circuity 922. Operation o circui~y
922 is c~tra~ed by ~put ~ ~upplied thereto b3r way of line 928.
Ci~ uitr~r 922 generates a dgDal o~ liDe 934 ~ coupled to antenna
818 to pen~t tra~lsmi~ion ~ infon ation dFnal6 therefrom.
Wb~e the pr~eDt in~ention hss been described in
coDIlection ~ e pr~erred embodiment~ sho~ in the ~iou~
~8, it is to be understood that other similar unbodiment6 may be
u~d and modifications and additions may be made to 1 he described
anbodi~s for performing ~e same fuDction of the present in~ention
~ithout de~ia~g ~hereh~ Tberefore, the present invention sho~d
not be limited to any ~gle embo~ment, but rather construed in breadth
and ~cope in aa:~nce ~il~ the recitation of ~he appended claim6.
