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`US007016676B2
`
`(12) United States Patent
`Walke et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,016,676 B2
`Mar.21,2006
`
`(54) METHOD, NETWORKAND CONTROL
`STATION FOR THE TWO-WAY ALTERNATE
`CONTROL OF RADIO SYSTEMS OF
`DIFFERENT STANDARDS IN THE SAME
`FREQUENCY BAND
`
`(58) Field of Classification Search ................ 455/434,
`455/435.2, 438, 414.4, 432.2, 207, 553.1,
`455/22, 314; 370/464--469, 395.5, 395.52,
`370/395.53
`See application file for complete search history.
`
`(75)
`
`Inventors: Bernhard Walke, Wuerselen (DE);
`Stefan Mangold, Aachen (DE)
`
`(73) Assignee: Koninklijke Philips Electronics N.V.,
`Eindhoven (NL)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 411 days.
`
`(21) Appl. No.:
`
`10/089,959
`
`(22) PCT Filed:
`
`Aug. 8, 2001
`
`(86) PCT No.:
`
`PCT/EPOl/09258
`
`§ 371 (c)(l),
`(2), ( 4) Date: Apr. 4, 2002
`
`(87) PCT Pub. No.: W002/13457
`
`PCT Pub. Date: Feb. 14, 2002
`
`(65)
`
`Prior Publication Data
`
`US 2002/0168979 Al
`
`Nov. 14, 2002
`
`(51)
`
`Int. Cl.
`H04Q 7/20
`(2006.01)
`(52) U.S. Cl. ................ 455/434; 455/553.1; 455/434.2;
`370/466; 370/467
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`5,239,662 A *
`5,710,766 A
`6,052,594 A *
`6,310,866 Bl*
`6,377,782 Bl *
`6,501,741 Bl*
`6,580,700 Bl *
`6,587,680 Bl *
`6,631,259 Bl *
`6,687,243 Bl *
`6,728,244 Bl *
`6,735,452 Bl *
`6,754,200 Bl *
`6,792,286 Bl *
`
`8/1993 Danielson et al. . . . . . . . . . . 709 /246
`1/1998 Schwendeman ............ 370/329
`............. 455/450
`4/2000 Chuang et al.
`10/2001 Kronestedt et al. ......... 370/330
`............. 455/3.01
`4/2002 Bishop et al.
`12/2002 Mikkonen et al. .......... 370/310
`............... 370/332
`6/2003 Pinard et al.
`7/2003 Ala-Laurila et al. ........ 455/411
`10/2003 Pecen et al. ............. 455/426.1
`2/2004 Sayers et al. ............... 370/356
`4/2004 Takabatake ................. 370/392
`5/2004 Foster et al. ............. 455/562.1
`6/2004 Nishimura et al.
`......... 370/349
`9/2004 Bharath et al.
`.......... 455/554.2
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`1119137 Al
`W09923790
`WO
`* cited by examiner
`
`1/2000
`10/1998
`
`Primary Examiner-Cong Van Tran
`
`(57)
`
`ABSTRACT
`
`interface-control protocol
`The invention relates to an
`method for a radio system, which has at least one frequency
`band provided for the two-way alternate utilization of a first
`and a second radio interface standard. The radio system
`comprises a number of stations, which each function in
`accordance with a first radio interface standard and/or in
`accordance with a second radio interface standard, in which
`a control station is provided that controls the two-way
`alternate utilization of the frequency band.
`
`9 Claims, 3 Drawing Sheets
`
`Zeit -
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`Broadcast Phase
`
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`
`Page 1 of 8
`
`

`

`U.S. Patent
`US. Patent
`
`Mar.21,2006
`hdar.21,2006
`
`Sheet 1 of 3
`Sheet170f3
`
`US 7,016,676 B2
`US 7,016,676 132
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`Page 3 of 8
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`

`

`U.S. Patent
`US. Patent
`
`Mar. 21, 2006
`Mar. 21, 2006
`
`Sheet 3 0f3
`Sheet 3 of 3
`
`US 7,016,676 B2
`US 7,016,676 B2
`
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`Page 4 of 8
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`Page 4 of 8
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`

`

`US 7,016,676 B2
`
`1
`METHOD, NETWORK AND CONTROL
`STATION FOR THE TWO-WAY ALTERNATE
`CONTROL OF RADIO SYSTEMS OF
`DIFFERENT STANDARDS IN THE SAME
`FREQUENCY BAND
`
`The invention relates to a method of alternate control of
`radio systems of different standards in the same frequency
`band.
`A radio system for wireless transmission of information is
`allowed to use transmission power only in accordance with
`standards. The national regulation authority determines on
`what frequencies with what transmission power and in
`accordance with what radio interface standard a radio sys(cid:173)
`tem is allowed to transmit. For this purpose there is provided 15
`for so-termed ISM frequency bands (Industrial Scientific
`Medical) that radio systems transmit in the same frequency
`band in accordance with different radio interface standards.
`An example of this is the US radio system IEEE802.lla and
`the European ETSI BRAN HiperLAN/2. The two radio 20
`systems transmit in the same frequency bands between 5.5
`GHz and 5.875 GHz with approximately the same radio
`transmission method, but different transmission protocols.
`In the event of interference, method were standardized for
`an active switching to another frequency within the permit- 25
`ted frequency band, for controlling transmission power and
`for the adaptive coding and modulation to reduce interfer(cid:173)
`ence. Radio systems of wideband LANs of the radio inter(cid:173)
`face standards ETSI BRAN HiperLAN/2 and IEEE802.lla
`utilize the same radio transmission method, a 64-carrier 30
`OFDM method and an adaptive modulation and coding.
`About the same modulation and coding methods (Link
`Adaptation, LA) are defined for the two standards.
`The Medium Access Control (MAC) of the two systems
`is totally different. ETSI BRAN HiperLAN/2 utilizes a 35
`centrally controlled reservation-based method in which a
`radio station takes over the role of a central instance co(cid:173)
`ordinating the radio resources. This central radio station
`(Access Point, AP) which may be an access point to the wide
`area network, periodically signals every 2 ms the MAC 40
`frame structure from the AP and the associated stations if
`required.
`The IEEE802.lla standard describes a CSMNCA (Car(cid:173)
`rier Sense Multiple Access/Collision Avoidance) method not
`based on reservations, in which all the radio stations listen 45
`in on the medium and assume that the channel is unused for
`a minimum duration (Short InterFrame Space, SIFS) before
`802.lla-MAC frames, thus user data packets, are transmit(cid:173)
`ted if necessary. The method is highly suitable for self(cid:173)
`organizing ad hoc networks, but requires positive acknowl(cid:173)
`edgements of all the packets. Measures supporting service
`quality (Point Coordination Function PCF) in addition allow
`the support of multimedia applications. FIG. 2 shows by
`way of example the sequence for media access in accor(cid:173)
`dance with IEEE802.lla. In accordance with a variant of the 55
`standard a station is to then transmit an RTS packet (Ready
`To Send) and wait for a CTS packet (Clear To Send) from
`the addressed station before it is allowed to transmit user
`data. All the other stations in the radio coverage area set a
`time monitoring (Network Allocation Vector, NAY) and do
`not transmit until the addressed station has sent an acknowl(cid:173)
`edgement (ACKnowledge, ACK).
`Wideband LANs in accordance with the HiperLAN/2 and
`802.lla standards will operate in the same frequency band
`in the future between 5.15 and 5.825 GHz. The wideband 65
`LANs work with Transmitter Power Control (TPC), it is
`true, with adaptive radio transmission methods and the
`
`2
`Dynamic Frequency Selection (DFS) to minimize the alter(cid:173)
`nating interfering effects, these methods, however, do not
`make optimum use and spreading possible of the radio
`channels over the stations which transmit in accordance with
`5 different standards. The guarantee of the service quality
`necessary for the multimedia applications is impossible in
`the case of interference caused by their own stations or
`stations of outside systems. In case of alternating interfer(cid:173)
`ence, systems do not work efficiently and occupy a fre-
`10 quency channel even at low transmission rates.
`It is an object of the invention to provide a method, a
`wireless network and a control station which make efficient
`use of radio transmission channels possible.
`This object is achieved for the method in accordance with
`the invention by an interface control protocol method for a
`radio system, which system comprises at least a frequency
`band provided for the alternate use of a first and a second
`radio interface standard, the radio system comprising sta(cid:173)
`tions which operate in accordance with a first radio interface
`standard and/or a second radio interface standard, respec(cid:173)
`tively, a control station being provided which controls the
`alternate use of the frequency band.
`The invention is based on the idea of providing a com(cid:173)
`prehensive standard exchange of implicit or explicit control
`information in systems that have the same radio transmis(cid:173)
`sion methods but different radio transmission protocols. This
`makes a simple and efficient use possible of a radio channel
`via a plurality of radio interface standards.
`The radio system comprises one or more stations. The
`stations may be, for example, computers of a wireless local
`area network. These stations may be arranged, for example,
`only for operation in accordance with a first or second radio
`interface standard. But it is also possible for stations to
`operate in accordance with both the first and the second
`radio interface standard.
`A first number of stations preferably forms a wireless
`local area network in accordance with a first radio interface
`standard and a second number of stations forms a wireless
`network in accordance with a second radio interface stan-
`dard. The first radio interface standard may be, for example,
`the HiperLAN/2 standard and the second radio interface
`standard may be the IEEE802.lla standard.
`For these two standards is reserved the frequency band
`from 5.15 GHz to 5.825 GHz.
`In accordance with the invention a control station is
`provided which controls the alternate use of the common
`frequency band of the two radio interface standards.
`The control station is preferably a station that may operate
`in accordance with both the first and the second radio
`50 interface standard.
`The control of the alternate use of the common frequency
`band may be effected in various ways. For example, it is
`possible to provide certain predefinable time intervals for the
`use of the first and second radio interface standard and
`allocate the frequency band alternately to the first radio
`interface standard and then to the second radio interface
`standard in a kind of time-division multiplex mode.
`However, it is advantageous to effect the allocation by
`means of adaptive protocols. The common radio channel can
`60 then be utilized more effectively particularly when the
`demand for transmission capacity in accordance with the
`first and the second radio interface standard varies.
`In the advantageous embodiment of the invention as
`claimed in claim 2, the control station is provided, on the one
`hand, for controlling the access to the frequency band for
`stations operating in accordance with the first radio interface
`standard. If the first radio interface standard is, for example,
`
`Page 5 of 8
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`

`

`US 7,016,676 B2
`
`3
`4
`the HiperLAN/2 standard, the control station performs the
`standard to interpret the radio channel as interfered and
`function of the central controller (Access Point AP) in
`occupy another radio channel for its own operation.
`accordance with this standard. In that case the stations of the
`The efficient common use of a radio channel by different
`HiperLAN/2 standard send a request for capacity to the
`radio systems may be achieved via a suitable control pro(cid:173)
`control station and the control station allocates transmission 5
`tocol method. Such a radio interface control protocol
`capacity to each respective station.
`method enables a first station of a radio system working in
`accordance with the first radio interface standard to control
`On the other hand, the control station is provided in an
`advantageous embodiment of the invention as claimed in
`the access times to the radio channel by other stations. For
`claim 2 for releasing the common frequency band for access
`this purpose this first station then has to carry out functions
`by stations operating in accordance with the second radio 10
`described in another, second radio interface standard in
`interface standard, if stations operating in accordance with
`addition to the functions laid down by its own first radio
`the first radio interface standard do not request access to the
`interface standard at times at which stations working in
`frequency band. In this advantageous embodiment of the
`accordance with the first radio interface standard do not send
`invention the first radio interface standard is given priority
`and do not expect information in accordance with the
`15 standard from the first station, while the first station or a
`over the second radio interface standard in this manner. The
`further station determines the duration for which the first
`release of the common frequency band for the second radio
`station is allowed to transmit in accordance with the second
`interface standard may be effected, for example, explicitly
`by the sending of control information to the stations of the
`radio interface standard. The duration of the operation in
`second radio interface standard.
`accordance with the second radio interface standard need not
`be determined exactly but may also be determined approxi(cid:173)
`Alternatively, it is possible, for example, that the point 20
`mately. A transmission in accordance with the first radio
`coordinator provided in accordance with the IEEE802.lla
`interface standard can provide that the first station termi(cid:173)
`standard operates as the central control station and controls
`nates the use of the radio interface in accordance with the
`the alternate access of stations of the first and second radio
`interface standard to the common frequency band. In this
`second radio interface standard without taking resulting
`advantageous embodiment of the invention the point coor(cid:173)
`25 interference into account in stations that send in accordance
`dinator could for example periodically render the common
`with the second radio interface standard.
`The object of the invention is achieved for the network by
`frequency band available to another radio interface standard,
`for example, to the HiperLAN/2 standard.
`a wireless network that has at least one frequency band that
`In the advantageous embodiment as claimed in claim 3,
`is provided for the alternate use by a first and a second radio
`the control is effected in that the control station determines 30
`interface standard, while the wireless network comprises
`the respective duration in which the stations operating in
`stations that work in accordance with the first and/or the
`accordance with the second radio interface standard can
`second radio interface standard, a control station being
`provided which controls the alternate use of the frequency
`utilize the common frequency band. Determining the dura(cid:173)
`tion may advantageously be effected as claimed in claim 4
`band.
`Several examples of embodiment of the invention will be
`in that the control station sends a broadcast signal which 35
`further explained below with reference to the drawing in the
`informs the stations of a time period in which the frequency
`FIGS. 1 to 3, in which:
`band can be used by stations operating in accordance with
`FIG. 1 shows the frame structure in accordance with the
`the second radio interface standard.
`It is an advantage of the invention that when radio systems
`ETSI BRAN HiperLAN/2 standard,
`FIG. 2 gives a diagrammatic representation of the access
`are operated in phases in which no information is sent or 40
`received by a radio station in accordance with a first radio
`to a radio channel in systems in accordance with the
`interface standard, the additional sending of information in
`IEEE802.lla standard, and
`FIG. 3 shows two wireless local area networks in accor(cid:173)
`accordance with another radio interface standard becomes
`dance with a first and a second radio interface standard.
`possible, so that the access to the radio channel can be
`FIG. 1 shows the structure of the HiperLAN/2-MAC
`controlled by competing radio systems.
`It is then possible for a first radio station operating in
`frame.
`FIG. 2 diagrammatically shows the media access in
`accordance with a first radio interface standard to addition(cid:173)
`ally carry out certain functions described in a second radio
`systems working in accordance with the radio interface
`interface standard, while the first radio station or a coordi(cid:173)
`standard IEEE802.lla.
`nating further radio station that transmits in accordance with 50
`In a HiperLAN/2 system the central controller can be
`the first radio interface standard determines the beginning
`controlled via the Access Point (AP) which periodically
`and duration of the phase that may be used by the first station
`generates the MAC frame and then transmits the data of the
`for transmission in accordance with the second radio inter(cid:173)
`broadcast phase to individually control the service quality
`(packet delay sending rate and so on) of individual links.
`face standard.
`Transmission in FIGS. 1 and 2 with respect to the asso-
`Depending on the radio interface standard, beginning and 55
`duration can be defined only approximately, while the
`ciated standards is understood to mean that a HiperLAN/2
`AP in a partially unused downlink, uplink and direct-mode
`respective standards are violated regularly or from time to
`phase could dispense with sending useless (dummy) infor(cid:173)
`time. The first station may preferably end the phase during
`mation and giving 802.11-systems no opportunity to observe
`which it transmits in accordance with the second radio
`interface standard, while disregarding resulting interference 60 an unused channel for a period of time SIFS and starting the
`run as shown in FIG. 2. The AP could readily regain the
`in stations operating in accordance with the second radio
`control in which the transmission in accordance with the
`interface standard.
`HiperLan/2 standard does not suppress the broadcast phase,
`The first radio station may, in addition to functions in
`but transmission takes place. Likewise, the function PCF of
`accordance with the second radio interface standard, also
`65 the 802.11 standard could be used to occasionally render the
`carry out functions that cause radio systems working in
`radio channel available to HiperLAN/2 systems with a time
`accordance with the second radio interface standard or radio
`limit (periodically).
`systems working in accordance with the first radio interface
`
`45
`
`Page 6 of 8
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`

`US 7,016,676 B2
`
`25
`
`30
`
`20
`
`5
`The alternate control of radio systems of different stan(cid:173)
`dards, which control is proposed here and discussed with
`respect to an example of the wideband LANs ETSI BRAN
`HiperLAN/2 and IEEE802.lla, may guarantee in a hetero(cid:173)
`geneous environment in which various radio systems simul(cid:173)
`taneously transmit very close together in the same spectrum,
`a decentrally controlled adaptivity relative to the transmis(cid:173)
`sion capacity available in the respective systems for the
`management of the respective current traffic supply, of the
`required service quality and of the environment of use. 10
`When the integrated controller in accordance with the inven(cid:173)
`tion is used, different radio systems may be made compatible
`in the way that they constructively coexist in the same
`frequency band and then can provide services that require a
`high service quality. The radio spectrum is clearly used more 15
`efficiently; without the implementation of the new method
`this is only possible with respective exclusively used radio
`channels.
`FIG. 3 diagrammatically shows two wireless local area
`networks.
`A first wireless local area network comprises three sta(cid:173)
`tions 10, 11 and 12. These three stations 10, 11 and 12 work
`in accordance with the first radio interface standard A, for
`example, in accordance with the HiperLAN/2 standard.
`A second wireless local area network includes four sta(cid:173)
`tions 14, 15, 16 and 17. These four stations 14, 15, 16 and
`17 work in accordance with the second radio interface
`standard B,
`for example, m accordance with
`the
`IEEE802.lla standard.
`The stations may be, for example, computers which
`include a radio interface. The communication between the
`individual stations is effected in a wireless fashion, for
`example, by radio.
`For wireless local area networks in accordance with the 35
`HiperLAN/2 and IEEE802.lla standards the frequency
`band is comprised between 5.15 GHz and 5.825 GHz.
`A central control station 13 is provided which controls the
`alternate access by the first wireless network and the second
`wireless network to the common frequency band.
`This may be effected in an advantageous manner in that
`the station 13 sends a broadcast message to the stations 14
`to 17 of the IEEE802.lla standard when the stations 10 to
`12 do not need transmission capacity. This broadcast mes(cid:173)
`sage preferably contains time information which informs the
`stations 14 to 17 of the IEEE802.11 standard how long they
`are allowed to utilize the common frequency band. During
`this time the control station 13 can also carry out functions
`in accordance with the IEEE802.lla standard, for example, 50
`also be used for data transmission in accordance with the
`IEEE802.lla standard.
`If the stations 10 to 12 of the first wireless network are
`HiperLAN/2 stations, the control station 13 preferably also
`operates as the central control station (Access Point) of the 55
`HiperLAN/2 network and co-ordinates its radio resources.
`In HiperLAN/2 systems it is planned beforehand at what
`time the stations are allowed to send. For this purpose the
`HiperLAN/2 systems have a central controller (Access
`Point, AP) which receives the requests for capacity from the 60
`various stations and assigns capacity accordingly. The cen(cid:173)
`tral control station 13 is preferably also provided for carry(cid:173)
`ing out the function of the access point of the HiperLAN/2
`standard. The central control station 13 then periodically
`signals every 2 ms the MAC frame structure in accordance 65
`with the requirements of the individual stations of the
`HiperLAN/2 network.
`
`6
`Alternatively, it is also possible, however, in HiperLAN/2
`systems for the function of the access point and the function
`of the alternating control of the access to the common
`frequency band by the first wireless network and the second
`5 wireless network to be realized in separate stations. In that
`case, however, with respect to the duration in which the
`frequency band can be utilized by the first or second radio
`interface standard a data exchange is necessary between
`these separate stations.
`Alternatively, it is possible, for example, for the point
`co-ordinator provided in accordance with the IEEE802.11
`standard to operate as a central control station and to control
`the alternate access to the common frequency band by
`stations of the first and second radio interface standards. In
`this embodiment the point co-ordinator would, for example,
`periodically render the common frequency band available to
`another radio interface standard, for example, to the Hiper(cid:173)
`LAN/2 standard.
`What is claimed is:
`1. An interface-control protocol method for a radio system
`which has at least one common frequency band that is
`provided for alternate use by a first and a second radio
`interface standard, the radio system comprising:
`stations which operate in accordance with a first radio
`interface standard and/or a second radio interface stan(cid:173)
`dard, and
`a control station which controls the alternate use of the
`frequency band,
`wherein the control station controls the access to the
`common frequency band for stations working in accor(cid:173)
`dance with the first radio interface standard and(cid:173)
`renders the frequency band available for access by the
`stations working in accordance with the second radio
`interface standard if stations working in accordance
`with the first radio interface standard do not request
`access to the frequency band.
`2. The method as claimed in claim 1, herein the control
`station determines the respective duration in which the
`stations working in accordance with the second radio inter-
`40 face standard are allowed to utilize the frequency band.
`3. The method as claimed in claim 1, wherein the control
`station sends a broadcast signal informing the stations of a
`time duration in which the common frequency band can be
`used by stations working in accordance with the second
`45 radio interface standard.
`4. The method as claimed in claim 2, wherein the duration
`of operation in accordance with the first and second radio
`interface standards is laid down only approximately while
`the respective standards are violated regularly or from time
`to time.
`5. The method as claimed in claim 1, wherein the control
`station also carries out functions which cause radio systems
`in accordance with the first radio interface standard to
`interpret the radio channel as interfered and to seize another
`radio channel for its own operation.
`6. An interface-control protocol method for a radio system
`which has at least one common frequency band that is
`provided for alternate use by a first and a second radio
`interface standard, the radio system comprising:
`stations which operate in accordance with a first radio
`interface standard and/or a second radio interface stan(cid:173)
`dard, and
`a control station which controls the alternate use of the
`frequency band,
`wherein the control station terminates the use of the radio
`interface in accordance with the second radio interface
`standard by transmitting in accordance with the first
`
`Page 7 of 8
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`US 7,016,676 B2
`
`7
`radio interface standard, without taking account of
`resulting interference in stations working in accordance
`with the second radio interface standard.
`7. An interface-control protocol method for a radio system
`which has at least one common frequency band that is 5
`provided for alternate use by a first and a second radio
`interface standard, the radio system comprising:
`stations which operate in accordance with a first radio
`interface standard and/or a second radio interface stan(cid:173)
`dard, and
`a control station which controls the alternate use of the
`frequency band,
`wherein the control station controls the access to the
`common frequency band by stations working in accor(cid:173)
`dance with the first radio interface standard and in that 15
`duration and type of control of the radio interface in
`accordance with the second radio interface standard is
`determined by a further station and transmitted to the
`control station.
`8. An interface-control protocol method for a radio system 20
`which has at least one common frequency band that is
`provided for alternate use by a first and a second radio
`interface standard, the radio system comprising:
`stations which operate in accordance with a first radio
`interface standard and/or a second radio interface stan- 25
`dard, and
`a control station which controls the alternate use of the
`frequency band,
`
`8
`wherein the control station, m addition to functions in
`accordance with the second radio interface standard,
`also carries out functions which cause radio systems in
`accordance with the second radio interface standard to
`interpret the radio channel as interfered and to seize
`another radio channel for its own operation.
`9. A wireless network comprising at least one common
`frequency band provided for alternate use by a first and a
`10 second radio interface standard, the wireless network com(cid:173)
`prising:
`stations which work in accordance with a first radio
`interface standard and/or in accordance with a second
`radio interface standard, and
`a control station which controls the alternate use of the
`common frequency band,
`wherein the control station controls the access to the
`common frequency band for stations working in accor(cid:173)
`dance with the first radio interface standard and(cid:173)
`renders the frequency band available for access by the
`stations working in accordance with the second radio
`interface standard if stations working in accordance
`with the first radio interface standard do not request
`access to the frequency band.
`
`* * * * *
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