(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2002/0068608 A1
`
`Souissi
`Jun. 6, 2002
`(43) Pub. Date:
`
`US 20020068608A1
`
`(54) METHOD AND APPARATUS FOR A
`SOFTWARE CONFIGURABLE WIRELESS
`MODEM ADAPTABLE FOR MULTIPLE
`MODES OF OPERATION
`
`(76)
`
`Inventor:
`
`Slim Salah Souissi, San Diego, CA
`(US)
`
`Correspondence Address:
`COUDERT BROTHERS
`3rd Floor
`600 Beach Street
`San Francisco, CA 94109 (US)
`
`(21)
`
`Appl. No.:
`
`09/925,565
`
`(22)
`
`Filed:
`
`Aug. 8, 2001
`
`Related US. Application Data
`
`application No.
`(63) Non-provisional of provisional
`60/224,727, filed on Aug. 11, 2000. Non-provisional
`of provisional application No. 60/227,723, filed on
`Aug. 24, 2000.
`
`Publication Classification
`
`(51)
`(52)
`
`(57)
`
`Int. Cl.7 ...................................................... H04M 1/00
`US. Cl.
`............................................ 455/557; 455/420
`
`ABSTRACT
`
`The present invention provides for a software configurable
`wireless modem that can be configured using software
`downloaded by a host computer. The user can select a
`preferred mode of operation, or mode selection can be done
`automatically based upon whether one or more predeter-
`mined criterion, such as a location of the modem, are met.
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`Patent Application Publication
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`Jun. 6, 2002 Sheet 2 0f 14
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`US 2002/0068608 A1
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`Patent Application Publication
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`Jun. 6, 2002 Sheet 5 0f 14
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`US 2002/0068608 A1
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`Fig. 4
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`Patent Application Publication
`
`Jun. 6, 2002 Sheet 6 0f 14
`
`US 2002/0068608 A1
`
`Fig. 5
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`Patent Application Publication
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`Jun. 6, 2002 Sheet 7 0f 14
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`Patent Application Publication
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`US 2002/0068608 A1
`
`Jun. 6, 2002
`
`METHOD AND APPARATUS FOR A SOFTWARE
`CONFIGURABLE WIRELESS MODEM
`ADAPTABLE FOR MULTIPLE MODES OF
`OPERATION
`
`[0001] This application claims the benefit of US. Provi-
`sional Application No. 60/224,727 filed Aug. 11, 2000 and
`US. Provisional Application No. 60/227,723 filed Aug. 24,
`2000.
`
`FIELD OF THE INVENTION
`
`[0002] The present invention is directed to wireless radio
`frequency modems and, more specifically,
`to detachable
`wireless radio frequency modems that can be configured for
`multiple modes of operation using software downloaded by
`a host computing device.
`
`BACKGROUND OF THE INVENTION
`
`[0003] Current wireless radio frequency (“RF”) modems
`that cooperatively operate with a host computing device
`(“host computer”) typically include: (1) a radio portion, also
`called an RF front end or an RF head; (2) a modulator/
`demodulator portion, also called a baseband processing unit
`or baseband chip; (3) a central processing unit (“CPU”) or
`processor; (4) a memory; and (5) an interface. During a
`receive mode of a wireless communication process, these
`modem components collectively to receive an electromag-
`netic RF signal, wherein the received RF signal contains
`information to be extracted. In a transmit mode, the com-
`ponents work collectively to transmit an electromagnetic RF
`signal, wherein the RF signal contains the information to be
`transmitted.
`
`[0004] During the wireless communications process, the
`modem components collectively operate to perform three
`principal modem functions: RF conversion, baseband pro-
`cessing and protocol stack control. During the receive mode,
`RF conversion is the preparation of the RF signal received
`at the antenna for demodulation and, during the transmit
`mode RF conversion is the preparation of the modulated
`baseband analog signal for transmission. During the receive
`mode, baseband processing is the demodulation of the
`modulated baseband analog signal to extract a plurality of
`data bits that correspond to the information being received,
`and during the transmit mode it is the generation of the
`modulated baseband analog signal from a plurality of data
`bits.
`
`[0005] As part of the above wireless communications
`process, data bits being transmitted are wrapped with pro-
`tocol bits of data to facilitate transmission, routing, and
`receiving of the data bits. Likewise, this protocol data must
`be removed to accurately reproduce, in the receiving RF
`modem, the data that was sent. The adding or stripping of the
`protocol bits, also called protocol stack control, is generally
`performed by the processor in the RF modem under the
`control of a protocol stack software program stored in the RF
`modem’s memory. Finally, the interface feeds the data bits
`from the host computer to the RF modem for processing and
`transmission and feeds to the host computer the reproduced
`data bits that were extracted from the RF signal.
`
`[0006] The host computer may typically be a laptop or
`palmtop computer, a Personnel Digital Assistant (PDA), a
`point of sale terminal, or some other computing system.
`
`Typical interfaces between the wireless RF modem and the
`host computer are RS-232, USB, Parallel Port, IrDa, PCM-
`CIA, or Compact Flash. However, other interfaces are also
`used, including a variety of proprietary interfaces. More-
`over, there are many wireless RF standards that must be
`considered in the design of any wireless RF modem. Some
`examples include: circuit switched commercial telecommu-
`nications standards including AMPS, CDMA (IS95A & B),
`and GSM; packet switched standards including CDPD,
`1XRTT, GPRS, EDGE, and W-CDMA; and proprietary
`wide area wireless networks such as Metricom, Re-Flex,
`FLEX, Mobitex, and ARDIS.
`
`[0007] Typically, detachable wireless modems are single
`mode and can operate according to only one of the above
`telecommunications standards. However, the trend is toward
`more flexible wireless modems that are capable of operating
`according to multiple modes, i.e., multiple telecommunica-
`tions standards. Prior art multi-mode modems are limited,
`however, in that they do not take advantage of the attached
`host computer in configuring the modem to operate under
`multiple standards. Most prior art multi-mode modems
`achieve the different modes of operation through additional
`hardware in the modem. Moreover, although some modems
`have components that are programmable, the modem typi-
`cally self-configures using software stored in the modem’s
`memory.
`
`[0008] What is needed is a detachable wireless RF modem
`that is constructed to be configured for different modes of
`operation with minimal need for additional hardware, result-
`ing in a lower cost multi-mode modem. What is also needed
`is a modem that uses its host computer for reconfiguration
`and eliminates the need for additional memory to store
`relevant reconfiguration software, again reducing the cost of
`the multi-mode modems.
`
`SUMMARY OF THE INVENTION
`
`[0009] The present invention is directed at addressing the
`above-mentioned shortcomings, disadvantages, and prob-
`lems of the prior art.
`
`[0010] Broadly stated, the present invention comprises a
`detachable software configurable wireless radio frequency
`(“RF”) modem that facilitates wireless data communications
`according to a plurality of modes of operation. The RF
`modem is constructed to plug into a host computing device
`having a storage unit and a central processing unit (“CPU”),
`said host computing device operative to download software
`into said RF modem in response to a trigger signal generated
`by said RF modem, to enable said RF modem to change
`from a present mode of operation to a selected alternate
`mode of operation. The RF modem according to the present
`invention includes an antenna for receiving or transmitting
`an electromagnetic RF signal, a software configurable RF
`front end coupled to said antenna for performing RF con-
`version, a software configurable baseband processor coupled
`to said RF front end for performing baseband processing, a
`software configurable modem CPU coupled to said base-
`band processor and said RF front end for performing pro-
`tocol stack control and for facilitating said RF modem mode
`change, and a modem reconfiguration trigger for detecting
`that at least one predetermined criterion has been met and for
`generating said trigger signal in response thereto that iden-
`tifies said selected alternative mode of RF modem operation.
`16
`
`16
`
`

`

`US 2002/0068608 A1
`
`Jun. 6, 2002
`
`The modem CPU operates in response to said downloaded
`software to reconfigure said RF front end, said baseband
`processor and said modem CPU so as to cause said RF
`modem to operate according to said selected alternative
`mode of operation.
`
`[0022] FIG. 8 is a flow diagram illustrating a method
`according to another embodiment of the present invention
`for configuring an RF modem to operate according to an
`alternative mode of operation, wherein the mode change is
`pursuant to a user’s request;
`
`In an alternate embodiment of the present inven-
`[0011]
`tion, the RF modem further comprising a geographic posi-
`tioning device coupled to said modem CPU for determining
`the geographic location of said RF modem.
`
`[0012] The present invention also comprises a method for
`generating a mode change in a detachable and software
`configurable wireless radio frequency (“RF”) modem from
`a present mode of operation to a selected alternate mode of
`operation. The method comprises the steps of: detecting
`whether at least one predetermined criterion has been met;
`scanning a predetermined plurality of RF modem modes of
`operation to determine one or more modes of operation that
`satisfy said at least one predetermined criterion; selecting a
`mode of operation from said one or more modes of operation
`determined in the previous step; generating said trigger
`signal to identify to said host computing device the identity
`of the mode of operation selected in the previous step; and
`configuring said RF modem using the software downloaded
`from said host computing device to cause said RF modem to
`operate according to said mode of operation selected by the
`method.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0013] The forgoing aspects and the attendant advantages
`of this invention will become more readily apparent by
`reference to the following detailed description, when taken
`in conjunction with the accompanying drawings, wherein:
`
`[0014] FIG. 1 is a schematic illustration of a prior art
`system 100 for wireless data communications comprising a
`wireless RF modem that is connected to a host computer;
`
`[0015] FIG. 2A shows a schematic illustration of a system
`according to a preferred embodiment of the present inven-
`tion comprising an RF modem that is adaptable to operate
`under a plurality of modes of operation and that plugs into
`a host computer;
`
`[0016] FIG. 2B is a schematic illustration of a preferred
`implementation of the RF Interface of FIG. 2A, and how the
`components of the RF Interface are interconnected to the
`Modem CPU and to the baseband processor;
`
`[0017] FIG. 3 shows a chip layout for the Modem of FIG.
`2A;
`
`[0018] FIG. 4 is a flow diagram illustrating a method
`according to one embodiment of the present invention for
`configuring an RF modem to operate according to an alter-
`native mode of operation;
`
`[0019] FIG. 5 is a flow diagram illustrating a method
`according to another embodiment of the present invention
`for configuring an RF modem to operate according to an
`alternative mode of operation;
`
`[0020] FIG. 6 is a block diagram illustrating a system
`detector implementation according to one embodiment of
`the present invention;
`
`[0021] FIG. 7 illustrates a plurality of criterion that, when
`met or detected, could provide the basis for reconfiguring the
`RF modem to operate according to an alternative mode of
`operation;
`
`[0023] FIG. 9 illustrates a display of a wireless PDA
`showing several
`icons from which a user can select
`to
`automatically reconfigure the software configurable RF
`modem according to the present invention;
`
`[0024] FIG. 10 illustrates a display of a computer, such as
`a laptop, showing a menu from which a user can select to
`automatically reconfigure the software configurable RF
`modem according to the present invention;
`
`[0025] FIG. 11 is a flow diagram illustrating a method
`according to another embodiment of the present invention
`for configuring an RF modem to operate according to an
`alternative mode of operation, wherein the mode change is
`pursuant to a user’s request;
`
`[0026] FIG. 12 is a flow diagram illustrating a method
`according to another embodiment of the present invention
`for configuring an RF modem to operate according to an
`alternative mode of operation, wherein the mode change is
`based on a modem generated list of compatible modes of
`operation; and, FIG. 13 is a flow diagram illustrating a
`method according to another embodiment of the present
`invention for configuring an RF modem to operate according
`to an alternative mode of operation, wherein the mode
`change is based upon the location of the wireless modem.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`[0027] FIG. 1 is a schematic illustration of a prior art
`system 100 for wireless data communications comprising a
`wireless radio frequency (“RF”) modem 110 that is con-
`nected at Controller Interface 125 to a host computer 120.
`RF modem 110 is constructed to function according to a
`single mode of operation, i.e., according to a single tele-
`communications standard.
`
`[0028] RF modem 110 comprises an Antenna 126, an RF
`head for RF conversion, a baseband processor for baseband
`processing, a Controller 113 that is a central processing unit
`(“CPU”) for modem 110 for performing protocol stack
`control, and an EEPROM 112, wherein a protocol stack
`software program is stored. The RF head includes an RF
`Switch 127, a Receiver 115, a Synthesizer 116 and a
`Transmitter 114, and the baseband processor includes a
`Demodulator 111 and a Modulator 117. Host computer 120
`includes a Power Source 124, a Processor 121 that is the
`CPU, a Memory 123 and an Operator Interface 122.
`
`[0029] The components of RF modem 110 are intercon-
`nected as shown by the solid lines with arrows between
`those components, wherein the direction of the arrows
`indicate the flow of data during the wireless data commu-
`nications process. The components of host computer 120 are
`interconnected as shown by the solid lines with arrows
`between those components, wherein the direction of the
`arrows indicate the flow of data during the wireless data
`communications process. Moreover, there are also double
`arrows connecting some of the components of host computer
`120, i.e., connecting Processor 121 with Memory 123 and
`connecting Processor 121 with Operator Interface 122.
`17
`
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`
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`
`These double arrows indicate that data flows in both direc-
`
`tions, during the wireless data communications process,
`between the connected components.
`
`[0030] Controller Interface 125 can be any standard inter-
`face that enables RF modem 110 to be dimensioned to
`
`connect to a host computing device. It can be dimensioned,
`for example, to fit within a cradle for a PDA host computer
`or to enable modem 110 to be dimensioned to correspond to
`a PCMCIA personal computer card, i.e., for a laptop com-
`puter. EEPROM 112 provides for program storage and
`variable storage for Controller 113, e.g., storing the protocol
`stack software program.
`
`[0031] FIG. 2A shows a schematic illustration of a system
`200 according to a preferred embodiment of the present
`invention. System 200 comprises an RF modem 225 that is
`adaptable to operate under a plurality of modes of operation
`and that plugs into host computer 210. When functioning
`according to a selected modem of operation, system 200
`achieves the same functionality as system 100 illustrated in
`FIG. 1. However, the significant difference between system
`100 and system 200 is that modem 225 of system 200 is
`software configurable and can function according to a plu-
`rality of modes of operation, and selection of a given mode
`of operation can be done manually by a user of system 200,
`or it can occur automatically based upon whether at least one
`predetermined criterion has been met, as discussed more
`fully below.
`
`[0032] Modem 225 comprises: software configurable RF
`Interface 260, which functions as the RF head for RF
`conversion; baseband processor 235, which includes soft-
`ware configurable digital signal processor (“DSP”) 240,
`JTAG 230, Digital I/Q I/F and Host I/F for baseband
`processing; software configurable Modem CPU 285, which
`is preferably an ARM 7 processor and is used to run the
`protocol stack software; Modem Configuration Trigger 205,
`which generates a trigger signal when the mode of operation
`of Modem 225 is to be changed, such as when at least one
`predetermined criterion has been met; GPS 280, which is a
`positioning device used to provide an accurate geographic
`location of modem 225 and which may be used as part of the
`mode changing process; RAM 250, which is used by base-
`band processor 235 and Modem CPU 285 as a working
`space; and ROM 255, which is used to store fixed variables,
`tables, and other data, that can be used by baseband pro-
`cessor 235 and Modem CPU 285. Modem 235 is connected
`
`to host computer 210. Host
`by an interface, not shown,
`Computer 210 comprises a Computer CPU 215, a Computer
`Hard Disk 220, and a Flash Memory 265. Host Computer
`210 can be, for example, a PDA or a laptop computer. Host
`Computer 210 is preferably coupled to Server Internet 275.
`
`[0033] The components of system 200 are connected as
`indicated by the lines between those components. The
`interface that connects modem 225 to the host computer,
`although not shown in FIG. 2A, can be any standard
`interface that enables RF modem 225 to be dimensioned to
`
`fit within a cradle for a PDA host computer or to enable
`modem 225 to be dimensioned to correspond to a PCMCIA
`personal computer card, i.e. for a laptop host computer, or
`the like.
`
`[0034] FIG. 2B is a schematic illustration of a preferred
`implementation of the RF Interface 260 shown in FIG. 2A,
`and how the components therein are interconnected to
`
`Modem CPU 285 and baseband processor 235. RF Interface
`260 preferably comprises: an Antenna 261; a Direct Con-
`version DSP radio frequency integrated circuit (“RFIC”)
`263 coupled to Antenna 261, baseband processor 235, and
`modem CPU 285; a Power Amplifier 262 coupled to Direct
`Conversion DSP RFIC 263 and baseband processor 235; and
`a Timing Generator 264 to supply a clock for Direct Con-
`version DSP RFIC 263, baseband processor 235 and Modem
`CPU 285.
`
`[0035] Modem 225 of FIG. 2A is preferably implemented
`as an integrated circuit chip. FIG. 3 shows a chip layout 300
`for Modem 225 of FIG. 2A. Chip 300 comprises an ARM
`7305, an RF Interface 360; a RAM 310, a ROM 370; a
`Digital I&Q I/F 380; and a DSP Core that includes an
`Interface 1 Processor 320, an Interface 2 Processor 330, an
`Interface 3 Processor 340, a JTAG 350 and a Host I/F 390.
`
`[0036] During operation of modem 225, Computer CPU
`215 controls the process whereby modem 225 is configured
`to operate according to a selected mode of operation, i.e., a
`change in the telecommunications standard. The applicable
`reconfiguration software is stored in FLASH memory 265
`and can be downloaded by host Computer CPU 215. Simi-
`larly, DSP code is stored in FLASH memory 265 and can be
`downloaded to programmable DSP processor 240. Alterna-
`tively, the DSP software and the protocol stack software can
`be stored in Computer Hard Disk 220 or in Internet Server
`275.
`
`[0037] FIG. 4 is a flow diagram illustrating a method 400
`according to one embodiment of the present invention for
`configuring an RF modem to operate according to an alter-
`nate mode of operation. At step 410, the RF modem detects
`that a modem mode change should be made based upon
`whether at least one predetermined criterion has been met.
`The Modem Configuration Trigger then scans a predeter-
`mined plurality of modes of operation of the RF modem,
`such as scanning for the coverage availability on other
`systems, to select a system in accordance with the one or
`more criterion having been met at step 420. When the
`modem selects one of said modes of operation at step 430,
`such as coverage on a preferred system, the modem gener-
`ates a trigger signal
`that
`is communicated to the host
`computer CPU to identify to the host computing device the
`identity of the mode of operation selected by the Modem
`Configuration Trigger at step 440. The host computing
`device responds to the trigger signal by downloading soft-
`ware to enable the modem to be configured according to the
`selected mode of operation. Finally, at step 450,
`the
`modem’s CPU uses the downloaded software to configure
`the modem according to the selected mode of operation.
`
`[0038] FIG. 5 is a flow diagram illustrating a method 500
`according to another embodiment of the present invention
`for configuring an RF modem to operate according to an
`alternate mode of operation. This method is identical to the
`method illustrated in FIG. 4, except that a timer is used to
`limit
`the amount of time that
`the modem scans for a
`
`preferred mode of operation. At step 500, the RF modem
`detects that a modem mode change should be made based
`upon whether one or more predetermined criterion has been
`met. The Modem Configuration Trigger then sets a timer and
`scans a predetermined plurality of modes of operation of the
`RF modem at step 520, such as scanning for the coverage
`availability on other systems in accordance with the one or
`18
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`
`more criterion having been met. If the modem fails to select
`one of said modes of operation at step 530, such as coverage
`on a preferred system, before the timer expires at step 560,
`then the modem continues to operate according to its present
`mode, at step 570. If the modem selects one of said modes
`of operation at step 530, such as coverage on a preferred
`system, the modem generates a trigger signal that is com-
`municated to the host computer CPU to identify to the host
`computing device the identify of the mode of operation
`selected by the Modem Configuration Trigger at step 540.
`The host computing device responds to the trigger signal by
`downloading software to enable the modem to be configured
`according to the selected mode of operation. Finally, at step
`550, the modem’s CPU uses the downloaded software to
`configure the modem according to the selected mode of
`operation.
`
`[0039] To facilitate proper scanning for an alternative
`mode or system of operation, the modem has to scan for
`different systems although the modem is not configured to
`decode those systems. This can be done in several ways. For
`instance, the modem may just tune to the already known
`frequency of the system subject to scanning and perform a
`simple received signal strength (“RSSI”) measurement. If
`the measured RSSI for that specific frequency is above a
`certain threshold,
`the modem can assume that
`there is
`coverage on that system. Another alternative is to have the
`modem implement a detector having necessary hardware
`and software to detect a certain list of systems. For example,
`a simple detector of a CDMA pilot channel or a GSM synch
`channel can be hard coded into the modem using dedicated
`hardware and software to detect the pilot or synch channel.
`
`[0040] FIG. 6 is a block diagram illustrating a system
`detector implementation according to one embodiment of
`the present invention. A system detector controller 610 is
`coupled to and used to control dedicated hardware and
`software (“SW/HW”) units 1 through N,
`illustrated as
`blocks 620, 630, 640 and 650, which are used to detect the
`presence of a control or a sync signal for 1 through N
`different systems. Each SW/HW unit is used to detect a
`separate and alternative system. System Detector Controller
`610 and SW/HW units 1 through N are coupled to the
`modem’s RF front end 660. Controller 610 can be imple-
`mented in software as part of the modem’s CPU, and the
`SW/HW units can be implemented in a separate ASIC or can
`be implemented in the modem’s digital signal processor. As
`such, the detector is constantly present in the modem to
`perform system detection.
`
`[0041] According to another embodiment of the present
`invention, the RF modem configuration trigger is external to
`the modem. For example, the trigger signal may be gener-
`ated by the user of the host computing device under the
`control of software resident in the host, thereby causing the
`desired change in the mode of operation of the modem.
`Another example would be to couple the trigger signal from
`a source external to both the host and the modem, e.g., via
`the internet.
`
`[0042] FIG. 7 illustrates a plurality of criterion that, when
`met or detected, could provide the basis for reconfiguring the
`modem to operate according to an alternative mode of
`operation. Detection of these criteria could occur either
`internally or externally to the modem. As FIG. 7 indicates,
`a request for a modem mode change could be triggered
`
`because the modem or the host computer detected that one
`or more of the following criteria were met: (1) criterion 700,
`a traffic load above a specified threshold; (2) criterion 710,
`a user request; (3) criterion 720, a coverage problem on the
`system currently in use; (4) criterion 730, a financial incen-
`tive that could be advertised to the user or automatically set
`as a preference, i.e., the user could set up the modem to
`automatically switch to the least expensive system available;
`(5) criterion 740, a desire by the user to always be connected
`to the highest data rate network; and (6) criterion 750, a
`desire by the user to be connected to the system with the best
`Quality of Service (“QOS”).
`
`[0043] FIG. 8 is a flow diagram illustrating a method 800
`according to another embodiment of the present invention
`for configuring an RF modem to operate according to an
`alternative mode of operation, wherein the mode change is
`pursuant to a user’s manual request. At step 810, a user
`indicates he or she would like to reconfigure the modem to
`operate, for example, according to a preferred wireless
`standard. At step 820, the user selects from a configuration
`menu a preferred frequency band. Upon receiving the
`request at step 830, the host computer CPU downloads from
`a storage unit the appropriate protocol stack, and installs it
`in the modem with the help of the modem’s CPU; down-
`loads from the storage unit the DSP code and configures the
`baseband DSP chip with the help of the modem’s CPU; and
`downloads from the storage unit software to configure the
`wireless modem RF front end hardware, including software
`for the direct conversion stage and software for the amplifier,
`and sends this software to the modem CPU to reconfigure
`the RF front end. At step 840, the modem configuration is
`complete, and the modem is now operational to function
`according to the selected alternative mode of operation.
`
`[0044] FIG. 9 illustrates a display of a wireless PDA
`showing several
`icons from which a user can select
`to
`automatically reconfigure the software configurable modem.
`FIG. 10 illustrates a display of a computer, such as a lapto