(12) United States Patent
`Trompower
`
`I IIIII IIIIIIII Ill lllll lllll lllll lllll lllll lllll lllll lllll llllll llll llll llll
`
`US006215982Bl
`US 6,215,982 Bl
`Apr. 10, 2001
`
`(10) Patent No.:
`(45) Date of Patent:
`
`(54) WIRELESS COMMUNICATION METHOD
`AND DEVICE WLTH AUXILIARY RECEIVER
`FOR SELECTING DIFFERENT CHANNELS
`
`(75)
`
`Inventor: Michael L. Trompower, Navarre, OH
`(US)
`
`(73) Assignee: Cisco Systems, m e., Saa Jose, CA (US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by O days.
`
`(21) Appl. No.: 08/672,426
`Jun. 28, 1996
`{22) Filed:
`..................................................... H048 15/00
`lnt. Cl.7
`(51)
`(52) U.S. Cl . ............................. 455/63; 455/452; 455/561
`(58) Field of Search .............................. 455/63, 454, 452,
`455/561, 62,513,514,161.1, 161 .2, 161.3,
`132,134,135; 375/220
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,216,432 * 8/ 1980 Jmazeki el al. ...................... 455/296
`4,792,984 • 12/ 1988 Matsuo ................................. 455/ 161
`5,101,501 * 3/1992 Gilhousen el al. .................. 455/442
`5,142,550
`8/1992 Tymes .
`7/ 1993 Ghisler el al. .
`5,230,082
`11/1993 Wheatley, ill .
`5,267,262
`5,287,384
`2/ 1994 Avery e l al. .
`5,361,399
`11/ 1994 Linquist et al..
`5,375,259 * 12/ 1994 Lee ....................................... 455/134
`1/1995 Cooper et al. .
`5,386,435
`5,390,366
`2/1995 Kasugai .
`5,442,627 * 8/1995 Viterbi el al. .................. , ....... 370/22
`
`5,452,471 *
`9/ 1995
`5,475,864 •
`12/1995
`5,483,666 *
`1/ 1996
`5,506,867 *
`4/ 1996
`7/1996
`5,539,923
`8/ 1996
`5,546,397
`5,594,949 *
`1/1997
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`5,640,414
`J2/J997
`5,697,055
`* 12/1997
`5,701,590
`5,794,145
`• 8/ 1998
`* J0/ !998
`5,822,686
`5,825,764
`10/1998
`5,940,452
`• 8/ 1999
`* 4/2000
`6,047,175
`* cited by examiner
`
`Leoplkd el al. ............ ......... 455/454
`Hamabe ................................. 455/63
`Yamada el al ......................... 455/62
`Kotzio el al ......................... 375/220
`Matsumoto.
`Mahany.
`Andersson el al. ................. 455/67.1
`Blakeney, 11 el al. .
`Gilhousen el al. .
`Fujnao1i ct al. .. ..................... 455/63
`Milam .................................. 455/426
`Lundberg el al. ................ 455/ J6l.3
`Rudolph ............................... 370/337
`Rich ..................................... 455/137
`Trompower .......................... 455/422
`
`Primary Examiner-Edward F. Urban
`Assistant Examiner-'filamun Gesesse
`{74) Attorney, A.gem, or Firm-Arter & Hadden LLP
`ABSTRACT
`
`(57)
`
`A wireless communication device and method which
`includes the introduction of a auxiliary receiver or trans(cid:173)
`ceiver which is included in a base station or mobile terminal
`in addition to a transceiver used to communicate between
`devices. The auxiliary receiver or transceiver serves to
`monitor substantially continuously the noise conditions on
`available communication channels other than the channel
`currently being utilized for communication between devices.
`Whenever the noise conditions on the current channel goes
`above a preset threshold level, for example, the base station
`or mobile terminal is informed by virtue of the operation of
`the auxiliary receiver or transceiver of the best alternative
`channel to which to change.
`
`38 Claims, 8 Drawing Sheets
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`Marvell Semiconductor, Inc. - Ex. 1006, Page 0001
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
`
`

`

`U.S. Patent
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`Apr. 10, 2001
`
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`Marvell Semiconductor, Inc. - Ex. 1006, Page 0002
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
`
`

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`Marvell Semiconductor, Inc. - Ex. 1006, Page 0003
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
`
`

`

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`Marvell Semiconductor, Inc. - Ex. 1006, Page 0004
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
`
`

`

`U.S. Patent
`
`Apr. 10, 2001
`
`Sheet 4 of 8
`
`US 6,215,982 Bl
`
`300
`
`START
`
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`SAMPLE NOISE
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`Fig. 4
`
`Marvell Semiconductor, Inc. - Ex. 1006, Page 0005
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
`
`

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`Marvell Semiconductor, Inc. - Ex. 1006, Page 0006
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
`
`

`

`U.S. Patent
`
`Apr. 10, 2001
`
`Sheet 6 of 8
`
`US 6,215,982 Bl
`
`300
`
`START
`
`CONDITIONS
`ON ALL
`CHANNELS
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`
`Fig. 6
`
`NO
`
`Marvell Semiconductor, Inc. - Ex. 1006, Page 0007
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
`
`

`

`U.S. Patent
`
`Apr. 10, 2001
`
`Sheet 7 of 8
`
`US 6,215,982 Bl
`
`201/352 \
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`
`Marvell Semiconductor, Inc. - Ex. 1006, Page 0008
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
`
`

`

`U.S. Patent
`
`Apr. 10, 2001
`
`Sheet 8 of 8
`
`US 6,215,982 Bl
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`Marvell Semiconductor, Inc. - Ex. 1006, Page 0009
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
`
`

`

`US 6,215,982 Bl
`
`1
`WIRELESS COMMUNICATION METHOD
`AND DEVICE WITH AUXILIARY RECEIVER
`FOR SELECTING DIFFERENT CHANNELS
`
`TECHNICAL FIELD
`The present invention relates generally to wireles.s com(cid:173)
`munication systems, and more particularly to a device used
`therein including an auxiliary receiver for selecting different
`channels.
`
`2
`mobile terminals registered to the base station indicating that
`the base station will be going temporarily off-line. This
`avoids the possibility of a mobile terminal transmitting
`information to the base station during such a time when the
`5 base station is not configured to receive such information.
`The base station then utilizes its transceiver to scan com(cid:173)
`munication conditions (e.g., noise conditions) on all other
`available channels.
`Based on such analysis, the base station then determines
`10 whether it is desirable to change to a new channel which
`may offer improved communication conditions (e.g., lower
`noise conditions). If more favorable conditions are available
`on another channel, the base station then returns to the
`original channel and attempts to inform all mobile terminals
`15 to jump to the newly selected channel. Otherwise, the base
`station simply remains on the original channel and informs
`the mobile terminals that the base station is back oo line.
`There arc, however, a number of drawbacks associated
`with such ao approach for determining to which channel the
`base station should change, if at all. The requirement that the
`base station go off-line in order to search for other channels
`significantly reduces overall system performance.
`Additionally, the base station typically assesses the noise
`conditions on each of the other channels over a short period
`of time and often leads to skewed results when, for instance,
`noise conditions arc high or low oo a particular channel due
`to conditions which are ooly temporary. Similar difficulties
`also exist for mobile terminals which evaluate the noise
`conditions in order to initiate channel switching.
`In view of the aforementioned shortcomings associated
`with conventional communication systems involving differ(cid:173)
`ent channels on which the base stations and mobile terminals
`may communicate, there is a strong need in the art for a
`system and met.hod for minimizing loss io system perfor(cid:173)
`mance associated with devices initiating a change in com(cid:173)
`munication channels. Further, there is a strong need in the art
`for a system and method of changing channels utilizing
`information which accounts for temporary fluctuations in the
`communication conditions on other channels.
`SUMMARY OF THE INVENTION
`The wireless communication device aod method accord-
`ing to the present ·invention minimizes the aforementioned
`problems associated with searching for a new channel.
`Specifically, the present invention introduces an auxiliary
`receiver or transceiver which is included in a base station or
`mobile terminal in addition to a transceiver used to com(cid:173)
`municate between devices. The auxiliary receiver or trans(cid:173)
`ceiver serves to monitor substantially continuously the noise
`conditions on available communication channels other than
`the channel currently being utilized for communication
`between devices. Whenever the noise conditions on the
`current channel goes above a preset threshold level, for
`example, the base station or mobile terminal is informed by
`55 virtue of the operation of the auxiliary receiver or trans(cid:173)
`ceiver as to t11e best alternative channel 10 whi.ch to change.
`Alternatively, even if the noise conditions on the present
`channel are not above a predetermined threshold, the base
`station or mobile terminal still may change to another
`60 channel if there is signilicaotly less noise on another chan(cid:173)
`nel. Further, since the auxiliary receiver or transceiver can
`substantially continuously monitor all other channels, an
`average noise condition can be determined so that temporary
`noise conditions on a given channel do not skew the selec-
`65 tioo process.
`According to one particular aspect of the invention, a
`wireless communication device is provided, including: a
`
`30
`
`25
`
`BACKGROUND OF THE INVENTION
`In recent years, the use of cellular communication sys(cid:173)
`tems having mobile terminals which communicate with a
`hardwired network, such as a local area network (LAN) and
`a wide area network (WAN), has become widespread. Retail
`stores and warehouses, for example, may use cellular com(cid:173)
`munications systems to track inventory and replenish stock.
`The transportation industry may use such systems at large
`outdoor storage facilities to keep ao accurate account of
`incoming and outgoing shipments. In manufacturing 20
`facilities, such systems are useful for tracking parts, com(cid:173)
`pleted products and defects.
`A typical cellular communication system includes a num(cid:173)
`ber of fixed base stations or access points interconnected by
`a system backbone. Also included in many cellular commu(cid:173)
`nication systems are intermediate base stations which are not
`directly connected to the system backbone. Intermediate
`base stations, often referred to as wireless base stations or
`repeaters, increase the area within which base stations
`connected to t11e system backbone can communicate with
`mobile terminals.
`Associated with each base station is a geographic cell. A
`cell is a geographic area in which a base station bas sufficient
`signal strength to transmit and receive data from a mobile 35
`terminal or other device with an acceptable error rate.
`Typically, base stations will be positioned aloog the back(cid:173)
`bone such that the combined cell area coverage from each
`base station provides full coverage of a building or site.
`Further, it is also typical to have the cell area of coverage 40
`from two or more base stations to overlap or be co-located.
`Wireles.s communication systems such as those described
`above require that a base station and a mobile terminal
`communicate on the same frequency channel in order to
`exchange information. Often times, the noise level on a 45
`particular channel may become excessive and therefore a
`base station, for example, will initiate a move to a different
`frequency channel where better system performance can be
`achieved. Prior to changing to a different frequency channel,
`however, the base station must go off-line from its current 50
`channel to search for other channel candjdates and to
`evaluate the current noise conditions of those channels.
`Unfortunately, by going off-line the base station cao oo
`longer communicate with other devices on what had been
`the current channel utilized by the base station. As a result,
`communications between the base station and any mobile
`terminals registered thereto are suspended so as to reduce
`overall system performance.
`As an example, in a known frequency agile direct
`sequence spread spectrum (DSSS) system a base station is
`able to select among a plurality (e.g., live) available chan(cid:173)
`nels on which to communicate. On occasion, the base station
`may determine that the noise conditions oo the current
`channel are too high for reliable communications and there(cid:173)
`fore decide to move to a new channel among the available
`channels. In order to determine which channel to move to,
`the base station broadcasts a message to be received by all
`
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`

`US 6,215,982 Bl
`
`4
`FIG. 7 is a block diagram of a mobile terminal including
`an auxiliary receiver or an auxiliary receiver and transmitter
`in accordance with the present invention; and
`FIG. 8 is a block diagram of a wireless base station
`including an auxiliary receiver or an auxiliary receiver and
`transmitter in accordance with the present invention.
`
`5
`
`20
`
`3
`lransceiver including a transmiller and a receiver for trans(cid:173)
`mitting and receiving wireless communications selectively
`on any of a plurality of channels; and an auxiliary receiver
`for evaluating communication conditions on at least one of
`the plurality o[ channels while the transceiver communicates
`on another of the plurality of channels, and for providing
`information based on the communication conditions to the
`transceiver.
`According to another aspect of the invention, a method is
`provided in relation to a wireless communication device 10
`including a transceiver having a transmitter and a receiver
`for transmitting and receiving wireless communications on
`any of a plurality of channels, and an auxiliary receiver. The
`method includes the steps o[: the transceiver communicating
`on a channel selected from the plurality of channels; the
`auxiliary receiver evaluating communication conditions on
`each of the plurality of channels while the transceiver
`communicates on the selected channel, and selecting another
`channel for the transceiver to communicate on from among
`the plurality of channels based on the information provided
`by the auxiliary receiver.
`In accordance with still another aspect of the invention, a
`cellular communication system is provided. The system
`includes a backbone; a plurality of base stations each
`coupled to the backbone; at least one mobile terminal, each 25
`of the at least one mobile tenninal communicating with the
`backbone via a selected one of the plurality of base stat ions,
`and each of the base stations including: a transceiver for
`communicating with the at least one mobile terminal and
`including a transmitter and a receiver for transmitting and 30
`receiving wireless communications selectively on any of a
`plurality o( channels; and an auxiliary receiver for evaluat(cid:173)
`ing communication conditions on at least one of the plurality
`of channels while the transceiver communicates with the at
`least one mobile terminal on another of the pluxality of 35
`channels, and for providing information based on the com(cid:173)
`munication conditions 10 the transceiver.
`To the accomplishment of the foregoing and related ends,
`the invention, then, comprises the featuxes hereinafter fully
`described and particularly pointed out in the claims. The 40
`following description and the annexed drawings set forth in
`detail certain illustrative embodiments o( the invention.
`These embodiments are indicative, however, of but a few of
`the various ways in which the principles of the invention
`may be employed. Other objects, advantages and novel 45
`features of the invention will become apparent from the
`following detailed description of the invention when con(cid:173)
`sidered in conjunction with the drawings.
`BRIEF DESCRJPTION OF THE DRAWINGS
`FfG. 1 is a block diagram of a wireless cellu.lar commu(cid:173)
`nication system in accordance with tbc present invention;
`FIG. 2 is a block diagram of a base station including an
`auxiliary receiver in accordance with the present invention;
`FIG. 3 is a table containing noise condition information
`which is maintained in memory based on information pro(cid:173)
`vided by the auxiliary receiver in accordance with the
`present invention;
`FIG. 4 is a flowchart suitable for programming the base
`station of FIG. 2 to select a new channel based on noise 60
`conditions in accordance with the present invention;
`FIG. 5 is a block diagram of a base station including an
`auxiliary receiver and transmitter according to another
`embodiment of the present invention;
`FIG. 6 is a flowchart suitable for programming the base
`station of FIG. 5 to select a new channel based on noise
`conditions in accordance with the present invention;
`
`15
`
`DESCRIPTION OF TI-IE PREFERRED
`EMBODIMENTS
`The present invention will now be described with refer(cid:173)
`ence to the drawings, wherein like reference numerals are
`used to refer to like elements throughout.
`Referring initially to FIG. 1, a wireless network in the
`form of a cellular communication system 100 is shown in
`accordance with the exemplary embodiment of ihe present
`invention. The cellular communication system 100 includes
`a local area network 105 having a system backbone 110 and
`a plurality of base stations 115 coupled thereto. The back(cid:173)
`bone 110 is shown 10 be a hardwired data communication
`path made of twisted pair cable, shielded coaxial cable or
`fiber optic cable, for example. Alternatively, the backbone
`110 couJd be wireless in nature so as to provide an added
`dimension of flexibility. As is cooveotiooal, each base
`station 115 serves as an access point through which wireless
`communications may occur between devices coupled to the
`system backbone 110 and one or more mobile terminals 117
`included in the system 100.
`To the exemplary embodiment, the system 100 is a direct
`sequence, spread spectrum (DSSS) system in which each of
`the base stations 115 is capable of communicating on any
`one of a plurality of channels at different respective fre(cid:173)
`quencies. Thus, for example, if the noise level for a particu(cid:173)
`lar channel on which a base station ll5 is operating becomes
`excessive, the base station ll5 will determine whether to
`initiate a change to another channel found to have less noise.
`In this sense the system 100 is considered to be frequency
`agile whereby each base station 115 can seleaively choose
`among a plurality of channels on which to operate. lo the
`event a base station 115 initiates a change to another
`channel, the base station 115 communicates such informa(cid:173)
`tion to any mobile terminals 117 which are registered to the
`base station 115. Each mobile terminal 117 is configured to
`adjust its own parameters accordingly so as to operate on the
`newly selected channel.
`By way of example, each base station US together with
`the other devices in the system are designed to operate in
`either the 902-928 MHz or 2.4-2.48 GHz bands. Such bands
`represent unlicensed bands provided by tbe FCC for low
`50 power communication devices in the U.S., although opera(cid:173)
`tion in other bands is certainly within the scope of the
`invention. Within each band there are five predefined chan(cid:173)
`nels A through Eat different respective frequencies on which
`DSSS communications can be carried out. Each base station
`55 115 is capable of selecting any one of the channels A through
`E on which to communicate as is discussed more fully
`below.
`According to conventional DSSS techniques, communi(cid:173)
`cations involving the base stations 115 and mobile terminals
`117 involve utilizing a predetermined spreading code known
`as a pseudo noise (PN) sequence to spread tbe data being
`transmitted. This involves spreading each data bit which is
`1ransmitted into a plurality of sub-bits, commonly referred to
`as chips, using the PN sequence. Data which is received is
`65 despread according to the same PN sequence.
`In order 10 expand the effective communication range of
`the base stations 115, one or more wireless base stations 120
`
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`

`US 6,215,982 Bl
`
`s
`also may be included in the cellular communication system
`100. As is conventional, each wireless base station UO
`associates itself, typically by registration, witb aootber base
`station, whether hardwired or wireless, such that a commu(cid:173)
`nication link is formed between itself and other devices 5
`situated on the system backbone 110.
`Each base station US, UO is capable of wirelessly
`communicating with other devices in the system 1()() via a
`respective antenna 125. A geographic cell 127 associated
`with each base station 115, 120 defines a region, or area of 10
`coverage, in which successful wireless communication may
`occur. Depending on the type of antenna US and the output
`power of the respective base station, the cell 127 may take
`one of several different forms and sizes. For example, in the
`event the antenna US is an omni-directional antenna, a 15
`generally spherical cell area coverage is obtained. However,
`a directed yagi-type antenna or other form of antenna could
`also be used as will be readily appreciated.
`According to the exemplary embodiment of the present
`invention, each base station US also includes an auxiliary 20
`antenna U9. The auxiliary antenna U9 preferably is of the
`same type as described above with reference to the antenna
`125 and provides equivalent cell coverage 127. As is dis(cid:173)
`cussed more fully below, the auxiliary antenna 129 is
`coupled to an auxiliary receiver or transceiver included in 25
`the base station US. The auxiliary receiver or transceiver is
`configured to operate substantially independently of a main
`transceiver also included in the base station US and which
`is used for carrying out conventional cellular communica(cid:173)
`tions. Specifically, the auxiliary receiver or transceiver in 30
`combination witb the antenna U9 allows the base station
`115 to scan substantialJy continuously the noise conditions
`of any or all or the available communication channels A
`through E to determine if, and when, the base station 115
`may wish to switch from one channel to another. For 35
`example, if a base station 115 is currently operating on
`channel A and the auxiliary receiver determines that noise
`conditions on channel C are much lower, the base station 115
`may initiate a change from channel A to channel C. Such
`configuration has advantages over prior art systems having 40
`only one transceiver aod one antenna, in that the base station
`115 is able 10 maintain continuous, uninterrupted commu(cid:173)
`nications with the mobile terminals 117 io its cell 127 area
`even during the scanning process.
`As previously mentfooed, the cellular communication
`system 100 includes one or more mobile terminals 117. Each
`mobile terminal 117 communicates with devices <m the
`system backbone UO via a selected base station 115, L20.
`Upon roaming from one cell 127 to another, the mobile
`terminal 117 is configured to associate itself with a new base
`station 115, 120.
`FIG. 2 represents a block diagram of a given base station
`115 within the system 100. The base station includes a main
`transceiver 200 and an auxiliary receiver 201 wbich are each
`controlled by a microprocessor 202. The main transceiver 55
`200 includes a transmitter 204 and a receiver 206 for
`respectively transmilling and receiving conventional cellular
`communications via the antenna 125. The transceiver 200 is
`conventional in design and is capable of operating oo any
`one of five different channels A through E as controlled by 60
`the microprocessor 202. Control signals and data are
`exchanged between the microprocessor 202, the transmitter
`204 and the receiver 206 by way of a cootroVdata bus 208
`connected therebetweeo. Since the particular design of the
`main transceiver 200 is generally cooveotiooal and is oot 65
`necessarily germane to the present invention, further detail
`is omitted.
`
`6
`The auxiliary receiver 201 as shown in FTG. 2 is provided
`in the base station 115 to scan substantially continuously the
`channels A through Eon which the main transceiver 200 is
`oot currently operating on in order to evaluate noise condi(cid:173)
`tions. Thus, the provision of the auxiliary receiver 201
`avoids the necessity of the receiver 206 io the main trans-
`ceiver 200 having to go "off-line" with respect to tbe mobile
`terminals 117 in order to evaluate noise conditions on the
`other available channels as in conventional devices.
`Consequently, overall system performance is greatly
`enbaoced as will be appreciated. Tbe auxiliary receiver 201
`includes a radio frequency (RF) section 222 and a modula(cid:173)
`tion section 224. As is described more fully below, the
`receiver 201 is controlled by the microprocessor 202 with
`respect to the operation of the RF section 222 and the
`modulation section 224. A memory 228 such as a RAM or
`the like is also included in the receiver 201 aod can serve as
`data storage. In addition, the memory 228 includes a non(cid:173)
`volatile portion for storing appropriate operating code to be
`executed by ihe microprocessor 202 for carrying out the
`functions described herein. The manner in which the micro-
`processor 202 can be programmed to carry out such func(cid:173)
`tions will be readily apparent to those having ordinary skill
`in the art based on the description provided herein.
`Signals which are received by the auxiliary antenna U9
`are provided to an RF downconvcrter circuit 234 included in
`the RF section 222. The RF downconverter circuit 234 is
`driven by a frequency syntbesizer 236 which produces an
`output frequency on line 238 which is input to the RF
`downcooverter 234. The RF dowocooverter circuit 234
`includes a mixer (not shown) which mixes tbe incoming
`signals from the antenna 129 down to a corresponding base
`band signal provided oo line 240. The frequency synthesizer
`236 is controllable by the microprocessor 202 via line 242
`in order to control the specific channel on which tbe receiver
`201 receives a signal. Specifically, the microprocessor 202
`provides control information to the frequency synthesizer
`236 which causes the synthesizer to selectively produce an
`output frequency on line 238 corresponding to the carrier
`frequency of any of channels A through E. Accordingly, by
`adjusting the output frequency of the frequency synthesiter
`236 the microprocessor 202 can determine whether the
`receiver 201 receives signals on channel A, 8, C, I) or E.
`Tbe RF section 222 also includes a conventional received
`45 signal strength indicator (RSSI) circuit 242 which produces
`an output on line 244 indicative of the RSSI level of any
`signals received on a particular channel at a given time. The
`output of the RSSI circuit 242 is provided to the micropro(cid:173)
`cessor 202 which samples the output as described below in
`50 order to evaluate the noise cooditioos of each particular
`channel A through E.
`The base band signal provided on line 240 from the RF
`dowacooverter circu it 240 is input to a PN decoder circuit
`250 included in the modu.lation section 224. The PN decoder
`circuit 250 is designed to despread the signal from the RF
`downconverter circuit 240 according to the particular PN
`sequence utilized in the system 100. The actual PN sequence
`is not critical to the invention, although the PN decoder
`circuit 250 is designed to include an output on line 252
`which is indicative of a degree of correlation between any
`data in the received signal and the PN sequence. As will be
`appreciated, as the receiver 201 receives signals on any
`given channel (i.e., chan.nels A through E), the receiver 201
`receives aoy noise which may be existent on the particular
`channel al that time. Io addition, the receiver 201 may
`receive intelligible signals which are being transmitted from
`the base stations 115, 120 or mobile terrniaals within the
`
`Marvell S