United States Patent [19J
`Grauel et ai.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,573,206
`Feb. 25, 1986
`
`[75]
`
`(54] METIIOD AND MEANS FOR AU.OCATING
`THE VOLUME OF TRAFFIC OVER
`DIFFERENT CONTROL CHANNELS OF A
`CELLULAR RADIO SYSTEM
`Inventors: Christoph Grauel, Feucht, Fed. Rep.
`of Germany; Pbllippe Duplessis;
`Alain Tarabout, both of Velizy
`Cedex, France
`[73] Assignee: U.S. Pbllips Corporation, New York,
`N.Y.
`(21] Appl. No.: 562,382
`[22] Filed:
`Dec. 16, 1983
`Foreign Application Priority Data
`[30)
`Dec. 17. 1982 (DE] Fed. Rep. of Oennany ....... 3246742
`(51]
`Int. Cl.' .......................... H04B 7/00; H04Q 7/02
`[52] u.s. Cl. ················•······················· 455/33; 455/34;
`455/56
`[58] Field of Search .................. 455/31.33, 34, 54, 56,
`455/38; 179/2 EB
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,582,787 6/1971 Muller eta! .•........................ 455/33
`3,898,390 8/1975 Wells eta! ............................ 455/34
`4,127,744 11/1978 Yoshikawa eta! ................... 455/54
`4,228,319 10/1980 De Jagger et al. .............. 179/2 EB
`
`4,360,297 11/1982 Bowen et al. ......................... 455154
`
`FOREIGN PATENT DOCUMENTS
`53930 4/1980 Japan ..................................... 455/33
`Primary Examiner-Jin F. Ng
`Attorney, Agent, or Firm-Thomas A. Briody; William
`J. Streeter; Leroy Eason
`
`[57]
`ABSTRACT
`A cellular radio system in which the mobile radio sta(cid:173)
`tions in the wne of any base radio station assign them(cid:173)
`selves to the control channels allocated to that base
`station so as to evenly spread the volume of traffic over
`such control channels. The base station transmits on
`each control channel a channel group code signifying
`the range of group code numbers allocated to that par(cid:173)
`ticuJar control channel. Each mobile station stores its
`identifying group code number, scans the group code
`numbers of all control channels, and assigns itself to the
`control channel having a channel group code which
`includes its group code number. The spread of traffic
`over the various control channels can be changed by
`the base radio station simply by changing the channel
`group codes of the various control channels, without
`addressing specific commands to the mobile radio sta(cid:173)
`tion.
`
`11 Claims, 2 Drawing Figures
`
`r--------------
`1
`
`~-~w ..... ~
`
`I
`
`""'-
`
`SJMI
`
`'
`.
`
`MOBILE RADIO S'tll10lo! ..J
`
`NS
`
`Lipoff Exhibit 10
`10/20/15
`
`C-Cation 2026
`Arris Group, Inc., and Cox Communications, Inc. v. C-Cation Technologies, LLC
`IPR2015-00635
`1
`
`

`
`U.S. Patent Feb. 25, 1986
`
`Sheet I of2
`
`4,573,206
`
`TRANS.
`
`-l
`I
`I
`I
`I
`I
`I
`I
`I
`I
`- - - - - - - - _ss_ - - - _j
`
`TST
`
`BASE RADIO STATION
`
`,-
`
`COMBINATIONAL
`SWITCHING CIRCUIT
`
`1
`I
`I
`I
`L_
`
`MOBILE RADIO STATION
`
`Spk
`
`MS
`
`FIG.l
`
`2
`
`

`
`U.S. Patent Feb. 25, 1986
`
`Sheet 2 of2
`
`4,573,206
`
`CHANNEL CONTROL CIRCU T
`f t p 0
`
`Sp21
`
`ABS1
`
`I
`CHANNEL CONTROL CIRCUIT)KSTl
`
`1
`
`KST2
`
`CHANNEL CONTROL CIRCUIT "A
`
`l
`
`1
`
`1
`
`\ KSTn
`
`BASE RADIO STATION
`
`BS ·
`
`FIG.Z
`
`3
`
`

`
`1
`
`4,573,206
`
`METHOD AND MEANS FOR ALLOCATING THE
`VOLUME OF TRAFFIC OVER DIFFERENT
`CONTROL CHANNELS OF A CELLULAR RADIO
`SYSTEM
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The invention concerns a process for spreading the
`volume of traffic over different control channels of a 10
`radio transmission system, and apparatus for practicing
`such a process.
`2. Description of the Prior Art
`In a radio communications system (radio transmission
`system) known from DE-AS 27 33 503 the service area 15
`(the entire primary coverage area) is divided up into a
`large number of zones (radio zones) (cellular system)
`and each radio zclne is allocated at least one control
`channel (organisation channel) and several traffic chan(cid:173)
`nels. In a radio zone with a large number of mobile 20
`telephone subscribers (mobile radio stations) the trans(cid:173)
`mitter/receiver in the radio station (base) has to be
`provided with several control channels. To simplify the
`transmission and reception separation filter the trans(cid:173)
`mission and reception frequency band is split up into an 25
`upper and a lower band. The mobile radio stations are
`divided up into at least two groups each of which uses
`one of the transmission and reception frequency bands.
`The division of the transmission and reception fre(cid:173)
`quency band into two bands is chosen so that both 30
`groups of mobile radio stations share a common band.
`At least some of the control channels are located in this
`common band.
`A mobile radio station of a first group selects a con(cid:173)
`trol channel, e.g. for the establishment of connections. 35
`To this end the mobile radio station scans the control
`channels allocated to the first group for one with a good
`signal-to-noise ratio. If the signal-to-noise ratio of the
`selected control channel deteriorates because of inter(cid:173)
`ference to the radio field propagation or for some other 40
`reason, then the mobile radio station, on receipt of a
`certain control channel code, can also use a control
`channel allocated to another group, e.g. the second
`group. This allocation of control channels of another
`group is only undertaken in a radio zone if it has a small 45
`number of mobile radio stations.
`If there are several control channels available in a
`radio zone, then the volume of traffic corresponding to
`the mobile radio stations located and registered as being
`in this radio zone is spread over the control channels of 50
`this radio zone. In the known radio transmission system
`(DE-AS 27 33 503) the mobile radio stations are split up
`into groups to reduce the cost of the transmitter and
`receiver separation filter. Regard for the traffic situa(cid:173)
`tion, in particular a system of control by spreading the 55
`volume of traffic over different control channels, is
`neither anticipated nor mentioned. If four control chan(cid:173)
`nels are allocated to a radio zone, for example, and if
`there are in that radio zone only two out of a total of
`four groups of mobile radio stations, then the volume of 60
`traffic in the zone is spread over two control channels
`allocated to on! y the two groups of mobile radio sta(cid:173)
`tions.
`If the number of control channels in a radio zone
`belonging to that radio woe or the frequency and con- 65
`sequently the channel number of a control channel
`changes, then the mobile radio stations should automati(cid:173)
`cally and independently assign themselves to the thus
`
`2
`formed new set of control channels. If, for example, a
`new control channel is allocated to the radio wne, then
`everything possible should be done to prevent the al(cid:173)
`ready existing control channels and the new control
`channel from becoming temporarily overloaded in the
`short term by a large number of individual transfers of
`mobile radio stations.
`The problem underlying the invention was to devise
`a process for spreading the volume of traffic over differ(cid:173)
`ent control channels of a radio wne. In the event of a
`change in configuration, i.e. in the event of a control
`channel failure, the mobile radio stations should require
`no individual change commands to a new control chan(cid:173)
`nel.
`
`SUMMARY OF THE INVENTION
`The process in accordance with the invention pro(cid:173)
`vides the means for an approximately uniform spread of
`the volume of traffiC over different control channels of
`a radio wne of a radio transmission system.
`Some of the many mobile radio stations are in radio
`contact with the base radio station.
`If the case of the known radio transmission system
`(DE-AS 27 33 503) when it comes to an establishment
`of connections from the base radio station to the mobile
`radio station the latter has to be called on all the control
`channels in the radio zone. This unnecessary overload(cid:173)
`ing of all the control channels can be avoided by the
`process according to the invention. At the same time
`the number of transfers of mobile radio stations on an
`overloaded control channel can be kept low. The vol(cid:173)
`ume of traffic on the different control channels at any
`one time can be determined in the base radio station by
`traffic metering. The variable number of groups in the
`radio transmission system known to both the base radio
`station and the mobile radio station is chosen so that in
`each radio wne the various groups are spread as evenly
`as possible. The number of groups (ntp) shows into how
`many groups the total number of mobile radio stations
`located in the radio coverage area of the base radio
`station have been divided. The mobile radio station can
`assign itself to a control channel in a clear-cnt fashion
`by combining the group code number with the number
`of groups and group code transmitted via the control
`channel. The group code (atp) in a control channel
`shows which groups of mobile radio stations are al(cid:173)
`lowed to use that channel. By changing it the base radio
`station has a simple means of controlling the spread of
`the volume of traffic over its different control channels.
`Advantageous versions of the invention are described
`in the subclaims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`In the drawings:
`FIG. 1 is a circuit block diagram of a radio transmis(cid:173)
`sion system comprising a base radio station and a mobile
`radio station in accordance with the invention; and
`PIG. 2 is a circuit block diagram of an alternative
`form of base radio station in the circuit of FIG. 1.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`The invention will now he described in greater detail
`and explained for different cases.
`The radio transmission system is made up of several
`levels that are built up on top of one another. The low(cid:173)
`est level consists of what are known as radio zones.
`
`4
`
`

`
`4,573,206
`
`4
`MS are divided into 100 groups TP. Each mobile radio
`station is identified by a group code number K which is
`part of a stored identification code mid of such mobile
`radio station MS. A mobile radio station MS may be
`allocated to one of the groups TP on the basis, for exam(cid:173)
`ple, of the last two figures y z of its identification code
`mid. The allocation criterion mtp is then the same as the
`two final figures y z. A mobile radio station MS with an
`identification code 59988 accordingly belongs to the
`I 0 group TP = 88. TI1e base radio station BS transmits a
`group code atp to the mobile radio stations MS on each
`control channel CCH. By comprising the received
`group code atp and its stored group code number K the
`mobile radio station MS can derive an unequivocal
`15 allocation to a control channel CCH. The group code
`atp transmitted by the base radio station BS to the mo(cid:173)
`bile radio stations MS can, for example, consist of two
`parts, a largest and a smallest identification code num(cid:173)
`ber ltp and ftp. A mobile radio station MS assigns itself
`20 to that control channel CCH for which the condition
`
`3
`Depending on the height of the aerial masts of the base
`radio stations BS and with a transmitter power of a
`maximum of 50 watts the radius of these radio zones can
`lie between 5 and 15 km. Each radio zone is covered by
`a base radio station BS, which can relay conversations
`from and to the public telephone network via radio
`relay equipmenL Several adjoining radio zones can be
`combined into what is known as a paging area. The
`locations of all the mobile radio stations MS are subject
`to constant monitoring by the base station where they
`are stored in an address book. If a mobile radio station
`MS changes its paging area, then a change is made in
`the address book.
`If a telephone subscriber of a public telephone net(cid:173)
`work wishes to contact a mobile radio station MS a
`selective call is transmitted in all the radio zones of the
`paging area in which the mobile radio station MS is
`registered at that moment.
`The transmission and reception frequency bands he 1
`for example, between the 860 and 960 MHz. The duplex
`distance between transmission and reception frequency
`bands can be 45 MHz and each transmission and recep~
`tion frequency band can he subdivided into channel
`widths of 25 kHz. The channels are used in duplex
`operation. Depending on the volume of traffic each 25
`radio zone of the radio transmission system is allocated
`a number of traffic channels and at least one control
`channel CCH. This means that in geographically ad(cid:173)
`joining radio zones different frequencies (control chan(cid:173)
`nels) are used. To distinguish between a control channel 30
`CCH and a traffic channel each of them is given a spe(cid:173)
`cial code. If a control channel CCH fails or is subject to
`interference any traffic channel can take over the func(cid:173)
`tions of the co~trol channel CCH by a change in code.
`In this way it is possible to dispense with the duplication 35
`of control channels CCH that would otherwise be nec(cid:173)
`e~arv for reasons of reliabilitv.
`In the radio transmission sv~tem known from DE-AS
`27 33 503 a mobile radio station, once switched on, runs
`an orientational search for the control channel with the 40
`best signal-to-noise ratio. The channel number of this
`control channel is stored and the mobjle radio station
`goe...~ into a state of rest. TI1e mobile radio station moni(cid:173)
`tors the signal-to-noise ratio of this control channel. If
`the signai~to-nolse ratio of the control channel stored at 45
`that moment falls below a given value, then the rnnbile
`radio station scans other control channels in a search
`mode and compares the signal-to--noise ratios. A change
`in radio zone can be identified by this comparison and
`the mobi1e radio station stores the channeJ number of 50
`Ll)e- corresponding control channel. Accordingly there
`are mobile radio stations in a radio zone which are
`ready to transmit and receive or which at a given mo(cid:173)
`ment establish connectjons with the pnblic telephone
`network or with a mobile radio statJon of the radio 55
`transmjssion svstem via the control channel CCH, ba~e
`radio stations ;nd radio relay equipment. In the known
`radio transmission system (DE-AS 27 33 50}) the mo(cid:173)
`bile radio st.atlon stc1res the control channel that has the
`highest signal-to-noise ratio. In this way, according to 60
`the traffic situation. the volume of traffic on different
`cor.trcJ channels of a radio zone mav varv.
`In the radio transmission svstern all the~ mobile radio
`~tations 1\1S located in its ~ea are divided up into a
`constant numbe-r ntp of g;-cups TP< Each mobile radlo
`sn:~tion is permanently and uncquivocaHy aHocated to
`one of these groups TP. To simplify the description it is
`3:S).Umed in the following that the mobile radio stations
`
`is satisfied. In the examples below mtp will be taken as
`being equal to K
`Case I
`At a given moment three control channels CCH I, 2
`and 3 are allocated to a radio zone, with the channel
`numbers 589, 614 and 765. The volume of traffic in the
`radio coverage area of the base radio station BS is
`evenly spread if each such control channel carries a
`third of the volume of traffic. In the group code atp
`transmitted on control channel CCH I (with the channel
`number cnr=589) the base radio station BS makes it
`knO\\<'D that the smallest identification code number
`ftp=OO and the largest identification code number
`ltp= 32. On control channel CCH2 (with the channel
`number cnr=614) the hase radio station BS rransnrits to
`the mobile radio station MS a smallest number ftp=33
`and a largest number ltp=.65. Correspondingly on con(cid:173)
`trol channel CCH3 (with the channel number cnr = 765)
`a smallest number ftp=66 and a largest number ltp=99.
`The mobile radio station MS with the group code num(cid:173)
`ber K ~ 88 (identification code 59988) assigns itself to
`control channel CCH3 because the condition
`
`66~ 88,~99
`
`is satisfied for this channel. The channel number
`cnr= 765 of control channel CCH3 can be stored in the
`mohile radio station MS. Because of thls unequivocal
`allocation the mobile railio stations MS can be paged by
`the base radio station BS on control channel CCH3.
`Having been switched on each mobile radio station
`MS so as.signs itself to a control channel CCH of a radio
`zone. In the subsequent course of events the mobile
`radio station MS continually che-cks that the condition
`for this control channel CCH is satisfied. lf this condi(cid:173)
`tion ce..'lses to be satisfier! then a search begins in the
`Inobilc radio station JvfS for a new control channel CCH
`which satisfies the condition at that moment. If several
`c0ntroi channels CCH satisfy this condition. then the
`mobile radio station MS wlll~ as a matter of prcferenceJ
`assign itself to the one with the highest signal-to-noise
`65 ratio or to the one received with the greatest field
`strength. If the base radio station BS transmits a code
`for the paging area in addirion to the group code atp,
`then a change of paging area can be identified in the
`
`5
`
`

`
`4,573,206
`
`20
`
`5
`mobile radio station MS. Only when the mobile radio
`station MS recognises such a change will there be any
`rerouting via the chosen control channel CCH of the
`new paging area.
`As a means of controlling the spread of the volume of
`traffic over its control channels the base radio station
`BS can change the largest and smallest numbers ltp and
`ftp. An uneven spread of the volume of traffic can be
`ascertained in the base radio station BS by traffic meter(cid:173)
`ing on the control channels CCH. In addition to the 10
`advantage that specific change commands are unneces(cid:173)
`sary for each individual mobile radio station MS when
`the largest and smallest numbers ltp and ftp change,
`there is the advantage of a reduction in the volume of
`traffic on the individual control channels CCH. In a Is
`radio wne a page to a particular mobile radio station
`MS must only be transmitted on one control channel
`CCH, since the mobile radio station MS, if at all, will
`have assigned itself to one particular control channel
`CCH of this radio zone.
`Case 2
`In this example it is assumed that the volume of traffic
`is divided up into the following proportions: 40% on
`control channel CCHI, 40% on control channel CCH2
`and 20% on control channel CCH3. Therefore, the base 25
`radio station BS reallocates the volume of traffic so the
`smallest identification code number ftp is set as 00 and
`the largest identification code number ltp as 39 on con-
`t ~ol channel CCHI, the smallest number ftp=40 and the
`largest number ltp=79 on control channel CCH2 and 30
`the smallest number ftp = 80 and the largest number
`ltp=99 on control channel CCH3. As a result of the
`change in the largest and smallest numbers ltp and ftp
`mobile radio stations MS with a group code number K
`of 33 to 39 change from control channel CCH 2 and 35
`assign themselves to control channel CCHJ. Mobile
`radio stations MS with a group code number K of 66 to
`79 (previously control channel CCH3) assign them(cid:173)
`selves to control channel CCH2.
`Case 3
`A change in configuration of the control channels
`CCH becomes necessary if, for instance, a control chan-
`nel CCH fails. In this example it has been assumed that
`control channel CCH2 fails and the base radio station
`BS or radio relay equipment designates a control chan- 45
`nel with channel number 623 as a substitute. The new
`control channel CCH2 with channel number cnr= 623
`(previously control channel CCH2 with channel num-
`ber cnr=614) takes over the functions of the failed
`control channel CCH2 by transmitting identifying so
`codes ranging from the smallest number ftp=33 10 the
`largest number ltp=65 to the mobile radio stations MS.
`Case 4
`As in case 3 it is assumed here that control channel
`CCH2 fails, with the difference that the base radio sta- 55
`tion BS or the radio relay equipment does not designate
`any new control channel CCH2 as a substitute. The base
`radio station BS transmits the smallest identifying code
`number ftp=OO and the largest identifying code number
`ltp=49 on control channel CCHI (with channel num- 60
`ber cnr=589). And on control channel CCH 2 (with
`channel number cor= 765, previously control channel
`CCH3) the base radio station BS transmits the smallest
`number ftp=50 and the largest ltp=99. The volume of
`traffic is therefore spread equally over control channels 65
`CCH I and CCH2. The mobile radio stations MS, which
`had previously assigned themselves to control channel
`CCH2, now spread themselves over control channels
`
`6
`CCHI and CCH2 in equal amounts. Mobile radio sta(cid:173)
`tions MS that have and reassign themselves find their
`new channel after a search.
`It is assumed here that the base radio station BS trans(cid:173)
`mits a 16 bit word as the group code atp on two control
`channels CCHl and CCH2. The number of mobile
`radio stations located in the radio coverage area of the
`radio transmission system is divided into 16 groups TP
`in accordance with a number of groups ntp = 16.
`The allocation criterion mtp is calculated in each
`mobile radio station MS. That is, for example. the re(cid:173)
`mainder of the division of the stored group code num(cid:173)
`ber K by the number of groups ntp. Thus, the mobile
`radio station MS with the group code number K=88
`determines the criterion mtp to be equal to 8 (i.e., the
`remainder of 88/16).
`If the base radio station BS transmits a group code
`
`atp= llll 1111 0000 0000
`
`on control channel CCHJ and a group code
`
`atp=OOOOOOOO!lllllll
`
`on control channel CCH2, the smallest figure ftp and
`largest figure ltp of control channel CCH1 are 0 and 7
`respectively (on control channel CCH2 ftp=8 and
`ltp= 15). The mobile radio station MS with the criterion
`mtp=8 consequently assigns itself to control channel
`CCH2.
`In this example the first bit of the group code alp is
`allocated the criterion mtp = 0, the second bit the crite(cid:173)
`rion mtp =I, etc., last bit being allocated the criterion
`mtp=15. The mobile radio stations MS assign them(cid:173)
`selves to a particular control channel CCH if such chan(cid:173)
`nel has, e.g., a logical I characteristic state at the bit
`location of the group code atp allocated to the criterion
`mtp. The mobile radio station MS for which mtp=8
`therefore assigns itself from the above information to
`40 control channel CCH2.
`The described spread of the volume of traffic over
`different control channels can be varied in steps.
`FIG. 1 shows a control device in the form of a block
`diagram. The base radio station BS contains memories
`Sp and Spntp, whose outputs are each connected to an
`input of a group control circuit TST, and n channel
`control circuits KSTl to KSTn, corresponding to the
`number n of allocated control channels CCH.
`Each channel control circuit (e.g. KSTl) has a ftrst
`memory Spl, whose input is connected to an output of
`the group control circuit TST and whose output is
`connected to an input of an inquiry control circuit
`ABSl. The output of the inqnlry control circuit ABSl
`is connected to the input of a transmitter St.
`Located in the mobile radio station MS are a receiver
`E and a first memory SpMa, whose output is connected
`to an input of a combinational switching circuit V.
`The mobile radio station also contains a second mem(cid:173)
`ory SpK, whose output is connected to an input of the
`combinational switching circuit V.
`Stored in the base radio station BS in the memory Sp
`is a number n equal to the number of control channels
`CCH allocated to the base radio station BS and in the
`memory Spntp the number of groups ntp of mobile
`stations. The two numbers n and ntp are fed to the
`group control TST which derives a group code atp for
`each control channel from these members, which is
`
`6
`
`

`
`4,573,206
`
`45
`
`7
`stored in the memory Spm (m= 1, ••• n) of the associ(cid:173)
`ated channel control KSTm.
`The group codes atp are read out and fed to the asso(cid:173)
`ciated transmitter Sn by means of the inquiry control
`ABSn.
`The transmitted group code atp is received in the
`receiver E located in the mobile radio station MS and is
`fed to the first memory SpMa. The stored group code
`atp is compared with the identifying group code num(cid:173)
`ber K of station MS stored in the second memory SpK lO
`by the combinational switching circuit V. Such com(cid:173)
`parison is made as described above. Available at a ter(cid:173)
`minal En of the combinational switching circuit V is a
`control signal for allocating the mobile radio station MS
`to one of the control channels CCH.
`FIG. 2 shows a a modified version of the system in
`FIG. 1 in which each channel control circuit KSTn
`(n= 1, ..• n) of the base radio station BS is provided
`with two memories Spll and Sp21. A smallest number
`ftp is stored in the frrst memory Spll and in the second 20
`memory a largest number ltp. These two numbers are
`used for the group code atp, as described above. The
`two memories Sp and Spntp and the group control
`circuit TST in the base radio station BS in FIG. 1 are
`unnecessary in this modified version of the system 25
`therein.
`What is claimed is:
`1. A process for spreading the volume of traffic over
`different control channels of a radio communication
`system in which a plurality of base radio stations form a 30
`cellular system of radio zones in a geographical ar(cid:173)
`rangement, the base radio station of each zone having a
`plurality of control channels and traffic channels allo(cid:173)
`cated thereto over which it communicates with a plural-
`ity of mobile radio stations in such zone, such process 35
`comprising:
`dividing the total number of mobile radio stations in
`the radio communication system into a number of
`groups (ntp) identified by respective channel group
`codes (atp), each such channel group code (atp) 40
`corresponding to a range of identifying group code
`numbers (K);
`storing in each mobile radio station (BS) a particular
`identifying code number (K) which identifies such
`mobile radio station (BS);
`transmission by each base radio station (BS) of re(cid:173)
`spective channel group codes (alp) on the respec(cid:173)
`tive control channels (CCH) allocated to it, and
`reception from such control channels (CCH) of
`such channel group codes (atp) by the mobile radio 50
`stations (MS) in the zone of such base radio station
`(BS);
`causing each mobile radio station (MS) to compare
`the channel group codes (atp) received thereby
`with the identifying code number (K) stored 55
`therein to select the channel group code (atp)
`which corresponds to such stored identifying code
`number (K);
`and causing each mobile radio station (MS) to assign
`itself to the control channel (CCH) which corre- 60
`sponds to the channel code group (alp) selected by
`such mobile radio station (MS).
`2. A process as in claim 1, in which the identifying
`code number (K) stored in any mobile radio station
`(MS) is part of a complete identification code (mid) 65
`which is stored in such mobile radio station (MS).
`3. A process as in claim 2, in which the group code
`number (K) is derived from the final two figures (yz) of
`
`8
`the identification code (mid) stored in the mobile radio
`station (MS).
`4. A process as in claim 1, in which the base radio
`station (BS) transmits a largest and a smallest number
`(ltp and ftp) to the mobile radio stations (MS) as part of
`each channel group code (atp).
`5. A process as in claim 1, in which !'RCh group code
`(atp) is in the form of a series of binary digits, the loca(cid:173)
`tion of each individual binary digit corresponding to a
`particular identifying code number (K).
`6. A process as in claim 1, in which the mobile radio
`station (MS) derives a criterion (mtp) from its identify(cid:173)
`ing code number (K), and compares the criterion (mtp)
`with each channel group code (atp) in order to deter-
`IS mine the control channel ( CCH) to which to assign
`itself.
`7. A process as in claim 6, in which the criterion (mtp)
`is the remainder of the division of the identifying code
`number (K) of the mobile radio station (MS) by the
`number of groups (ntp) into which the total number of
`mobile radio stations in the radio communication sys(cid:173)
`tem are divided.
`8. A process as in claim 6, in which the criterion (mtp}
`is the same as the last two figures (yz) of the complete
`identification code (mid) of the mobile radio station
`(MS).
`9. A process as in ·claim 1, in which each base radio
`station (BS) determines the group code (atp) of each of
`the control channels (CCH) allocated to it.
`10. A process as in claim 9, in which the base radio
`station (BS) determines the group codes (atp) so as to
`equalize the volume of traffic on all the control chan·
`nels (CCH) allocated to it.
`11. In a radio communication system wherein a plu(cid:173)
`rality of base radio stations form a cellular system of
`radio zones corresponding thereto in a geographical
`arrangement, the base radio station of each zone having
`a plurality (n) of control channels (CCH) and traffic
`channels allocated thereto over which it communicates
`with a plurality of mobile radio stations in such zone,
`the total number of mobile radio stations in the radio
`communication system being divided into a number of
`groups identified by respective channel group codes
`(atp) each of which corresponds to a range of identify(cid:173)
`ing code numbers (K), each base radio station compris(cid:173)
`ing a transmitter and each mobile radio station compris(cid:173)
`ing a receiver; apparatus for spreading the volume of
`traffic over the control channels allocated to any base
`radio station (BS), such apparatus comprising:
`a plurality (n) of channel control circuits (KST) re(cid:173)
`spectively corresponding to the control channels
`(CCH) allocated to the base radio station (BS);
`each of said channel control circuits (KST) compris(cid:173)
`ing means for storing codes indicating the range of
`identifying code numbers of one of said channel
`group codes (atp), whereby respective codes are
`associated with
`respective control channels
`(CCH);
`the input of each channel control circuit being con(cid:173)
`nected to the storing means and the output of each
`channel control circuit being connected to the
`radio transmitter thereof to convey said stored
`codes thereto for transmission over such control
`channel (CCH);
`first and second memory means comprised in each of
`said mobile radio stations (MS), the second mem(cid:173)
`ory means of each mobile radio station (MS) stor-
`
`7
`
`

`
`4,573,206
`
`9
`ing a code number identifying such mobile radio
`station (MS);
`the receiver in each mobile radio station (MS) being
`adapted to receive the codes transmitted by the
`transmitters of all control chanRels and to convey
`them to the first memory means comprised in such
`mobile radio station (MS) for storing therein;
`and a combinational switching circuit comprised in
`each mobile radio station (MS) adapted to compare
`
`10
`the stored identifying code number in the second
`memory means therein with the code stored in the
`first memory means therein and to produce a con(cid:173)
`trol signal signifying the control channel (CCH)
`corresponding to the identifying code number of
`said mobile station, such control signal causing
`such mobile radio station (MS) to allocate itself to
`such control channel (CCH).
`• • • * •
`
`10
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`15
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`20
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`25
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`30
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`35
`
`40
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`45
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`50
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`55
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`60
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`65
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`8