USOO7023833B1
`
`(12)
`
`United States Patent
`Aiello et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,023,833 B1
`Apr. 4, 2006
`
`(54) BASEBAND WIRELESS NETWORK FOR
`ISOCHRONOUS COMMUNICATION
`
`(75) Inventors: Roberto Aiello, Palo Alto, CA (US);
`Stephan Gehring, Palo Alto, CA (US);
`William Lynch, Palo Alto, CA (US);
`Krisnawan K. Rahardja, San Jose, CA
`(US); Gerald Rogerson, Morgan Hill,
`CA (US); Carlton J. Sparell, Palo
`Alto, CA (US)
`
`(73) Assignee: Pulse-LINK, Inc., Carlsbad, CA (US)
`(*) Notice:
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.: 09/393,126
`(22) Filed:
`Sep. 10, 1999
`
`(51) Int. Cl.
`(2006.01)
`A04O 700
`Ath 92 3.
`(
`.01)
`(52) U.S. Cl. ....................... 370/348; 370/329; 370/337
`(58) Field of Classification Search ........ 370/321-322,
`370/324, 326, 328-330, 336 337,347–348,
`370/350, 437, 442 443, 447,503, 345, 280,
`370/310, 312–314; 455/403, 418, 426, 450,
`455/452, 462, 464, 41, 507, 517. 518
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
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`FOREIGN PATENT DOCUMENTS
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`EP
`
`(Continued)
`OTHER PUBLICATIONS
`Fernando Ramirez-Mireles, "On Performance of Ultra
`Wideband Signals in Gaussian Noise and Dense Multipath.”
`Paper 99C265, Accepted for Publication in the IEEE Trans
`actions on Vehicular Technology, pp. 1-9.
`
`(Continued)
`Primary Examiner Chi Pham
`Assistant Examiner—Ronald Abelson
`(74) Attorney, Agent, or Firm Pulse-LINK, Inc.; Peter
`Martinez: Steven Moore
`
`(57)
`
`ABSTRACT
`
`A wireless communication network system apparatus which
`provides for isochronous data transfer between node devices
`of the network, which provides at least one master node
`device which manages the data transmission between the
`other node devices of the network, which avoids or reduces
`interference from other wireless products and which
`resolves random errors associated with wireless technology
`including multipath fading. The system provides a commu
`nication protocol which shares the wireless transport
`medium between the node devices of the network, and
`which provides each node device on the network a desig
`nated transmit time slot for data communication.
`
`76 Claims, 6 Drawing Sheets
`
`10
`
`N
`
`12
`
`W
`
`18
`
`/ 20
`
`\
`
`NM
`
`20a
`
`2s
`
`V
`
`SLAVE 1
`
`14a
`
`14
`
`SLAVE3
`
`4c
`
`4.
`
`Uniloc Ex. 2002
`Microsoft v. Uniloc
`IPR2019-01116
`1
`
`

`

`US 7,023,833 B1
`Page 2
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`FOREIGN PATENT DOCUMENTS
`
`EP
`EP
`
`O 817 399 A2
`O 825 T94 A2
`
`1/1998
`2?1998
`
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`US 7,023,833 B1
`Page 3
`
`EP
`EP
`EP
`WO
`WO
`WO
`WO
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`
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`O 817 399 A3
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`O 825 T94 A3
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`OTHER PUBLICATIONS
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`Angeles, CA 90089-2565 USA, pp. 1-4.
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`37-43.
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`
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`neers, pp. 1-103, 1998.
`* cited by examiner
`
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`U.S. Patent
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`Apr. 4, 2006
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`Sheet 1 of 6
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`US 7,023,833 B1
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`U.S. Patent
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`Apr. 4, 2006
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`Sheet 2 of 6
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`US 7,023,833 B1
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`Apr. 4, 2006
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`Sheet 3 of 6
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`US 7,023,833 B1
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`IPR2019-01116
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`U.S. Patent
`U.S. Patent
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`Apr. 4, 2006
`Apr.4, 2006
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`FRAME58
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`Sheet 4 of 6
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`US 7,023,833 B1
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`FIG.4
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`U.S. Patent
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`Apr. 4, 2006
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`Sheet S of 6
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`US 7,023,833 B1
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`U.S. Patent
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`Apr. 4, 2006
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`US 7,023,833 B1
`
`1.
`BASEBAND WIRELESS NETWORK FOR
`ISOCHRONOUS COMMUNICATION
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`This invention pertains generally to network systems for
`exchanging data across a shared medium. More particularly,
`the invention is a wireless communication network system
`for isochronous data transfer between node devices of the
`network system that provides at least one master node
`device which manages the data transmission between slave
`node devices of the network system, and which further
`provides a time division multiple access frame definition
`which provides each node device on the network system a
`transmit time slot for communication.
`2. The Prior Art
`Network systems for data communication exchange have
`been evolving for the past several decades. Particularly,
`computer network systems have been developed to
`exchange information and provide resource sharing. Net
`work systems generally comprise one or more node devices
`which are interconnected and capable of communicating.
`The most common network systems today are “wired local
`area networks (LANs) and wide area networks (WANs).
`Normally, node devices participating in Such wired networks
`are physically connected to each other by a variety of
`transmission medium cabling schemes including twisted
`pair, coaxial cable, fiber optics and telephone systems
`including time division Switches (T-1, T-3), integrated Ser
`vices digital network (ISDN), and asymmetric digital sub
`scriber line (ADSL). While wired solutions provide
`adequate bandwidth or data throughput between node
`devices on the network, users participating in Such networks
`are generally restricted from mobility. Typically, users par
`ticipating in a wired network are physically limited to a
`specific proximity by the length of the cable attached to the
`user's node device.
`Many common network protocols in use today are asyn
`chronous and packet based. One of the most popular is
`Ethernet or IEEE 802.3. These types of networks are opti
`mized for bursts of packetized information with dynamic
`bandwidth requirements settled on-demand. This type of
`network works well for many data intensive applications in
`computer networks but is not ideal for situations requiring
`consistent delivery of time-critical data Such as media
`streams. Media streams typically require connection ori
`ented real-time traffic. Most media stream applications need
`to establish a required level of service. Dedicated connec
`tions are required with a predictable throughput. Low traffic
`jitter is often a necessity and can be provided with the use
`of a common network clocking reference.
`Firewire, or IEEE 1394, is an emerging wireline network
`technology that is essentially asynchronous, but provides for
`isochronous transfers or 'sub-actions'. Isochronous data is
`given priority, but consistent time intervals of data transfer
`is limited by mixing isochronous and purely asynchronous
`transfers.
`Universal Serial Bus (USB) is a popular standard for
`computer peripheral connections. USB Supports isochro
`nous data transfer between a computer and peripheral
`devices. The computer serves as bus master and keeps the
`common clock reference. All transfers on USB must either
`originate or terminate at the bus master, so direct transfers
`between two peripheral devices is not supported.
`Wireless transmission provides mobile users the ability to
`connect to other network devices without requiring a physi
`
`10
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`25
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`2
`cal link or wire. Wireless transmission technology provides
`data communication through the propagation of electromag
`netic waves through free space. Various frequency segments
`of the electromagnetic spectrum are used for Such transmis
`sion including the radio spectrum, the microwave spectrum,
`the infrared spectrum and the visible light spectrum. Unlike
`wired transmission, which is guided and contained within
`the physical medium of a cable or line, wireless transmission
`is unguided, and propagates freely though air. Thus the
`transport medium air in wireless communication is always
`shared between various other wireless users. As wireless
`products become more pervasive, the availability of airspace
`for data communication becomes proportionally more lim
`ited.
`Radio waves travel long distances and penetrate solid
`objects and are thus useful for indoor and outdoor commu
`nication. Because radio waves travel long distances, radio
`interference between multiple devices is a common prob
`lem, thus multiple access protocols are required among radio
`devices communicating using a single channel. Another
`common problem associated with wireless transmission is
`multi-path fading. Multipath fading is caused by divergence
`of signals in space. Some waves may be refracted off
`low-lying atmospheric layers or reflected off objects such as
`buildings and mountains, or indoors off objects Such as walls
`and furniture and may take slightly longer to arrive than
`direct waves. The delayed waves may arrive out of phase
`with the direct waves and thus strongly attenuate or cancel
`the signal. As a result of multipath fading, operators have
`resorted to keeping a percentage of their channels idle as
`spares when multipath fading wipes out some frequency
`band temporarily.
`Infrared communication is widely used for short-range
`communication. The remote controls used on televisions,
`VCRs, and stereos all use infrared communication. The
`major disadvantage to infrared waves is that they do not pass
`through solid objects, thus limiting communication between
`devices to “line of sight'. These drawbacks associated with
`the current implementation of wireless technology in net
`work systems have resulted in mediocre performance and
`periodic disruption of operations.
`In addition to the above noted drawbacks of Firewire and
`USB, there are currently no standards for wireless imple
`mentations of either. Of the wireless networks in use today,
`many are based at least in part on the IEEE 802.11 (wireless
`ethernet) extension to IEEE 802.3. Like wireless ethernet,
`this system is random access, using a carrier sense multiple
`access with collision detect (CSMA-CD) scheme for allow
`ing multiple transmitters to use the same channel. This
`implementation suffers from the same drawback of wireline
`ethernet described above.
`A similar implementation intended for industrial use is
`that of HyperlanTM. While still an asynchronous protocol,
`HyperlanTM uses priority information to give streaming
`media packets higher access to the random access channel.
`This implementation reduces, but does not eliminate the
`problems of sending streaming media across asynchronous
`networks.
`The Home-RF consortium is currently working on a
`proposal for a wireless network specification suitable for
`home networks. The current proposal specifies three types of
`wireless nodes, the connection points (CP), isochronous
`devices (I-nodes), and asynchronous devices (A-nodes).
`Isochronous transfers on the Home-RF network are intended
`for 64-kbps voice (PSTN) services and are only allowed
`between I-node devices and the CP device that is connected
`to the PSTN network. There is no allowance in the Home-RF
`
`IPR2019-01116
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`

`3
`specification for alternative methods of isochronous com
`munication Such as might be required for high quality audio
`or video.
`The Bluetooth Special Interest Group'TM has developed a
`standard for a short range low bit-rate wireless network. This
`network standard does overcome some of the shortcomings
`of random access networks, but still lacks some of the
`flexibility needed for broadband media distribution. The
`Bluetooth network uses a master device which keeps a
`common clock for the network. Each of the slave devices
`synchronizes their local clock to that of the master, keeping
`the local clock within +/-10 microseconds (usecs). Data
`transfer is performed in a Time Division Multiple Access
`(TDMA) format controlled by the master device. Two types
`of data links are supported: Synchronous Connection Ori
`ented (SCO) and Asynchronous Connection-Less (ACL).
`The Master can establish a symmetric SCO link with a slave
`by assigning slots to that link repeating with Some period
`Tsco. ACL links between the master and slave devices are
`made available by the Master addressing slave devices in
`turn and allowing them to respond in the next immediate slot
`or slots. Broadcast messages are also allowed originating
`only at the master with no direct response allowed from the
`slave devices.
`Several limitations exist in the Bluetooth scheme. All
`communication links are established between the master
`device and the slave devices. There are no allowances for
`slave-slave communication using either point-to-point or
`broadcast mechanisms. Additionally, isochronous commu
`nications are only allowed using symmetric point-to-point
`30
`links between the master device and one slave device. The
`TDMA structure used by Bluetooth is also limiting in that
`slot lengths are set at N*625 usecs where N is an integer
`O=1<=5.
`All of the above wireless network schemes use some form
`of continuous wave (CW) communications, typically fre
`quency hopping spread spectrum. The drawbacks of these
`systems are that they suffer from multipath fading and use
`expensive components such as high-Q filters, precise local
`high-frequency oscillators, and power amplifiers.
`Win et. al. have proposed using time-hopping spread
`spectrum multiple access (TH-SSMA), a version of Ultra
`Wide Band (UWB), for wireless extension of Asynchronous
`Transfer Mode (ATM) networks which is described in the
`article to Win, Moe Z., et. al. entitled “ATM-Based TH
`45
`SSMA Network for Multimedia PCS” published in “IEEE
`Journal on selected areas in communications'', Vol. 17, No.
`5, May 1999. Their suggestion is to use TH-SSMA as a
`wireless “last hop” between a wireline ATM network and
`mobile devices. Each mobile device would have a unique
`connection to the closest base station. Each mobile-to-base
`connection would be supplied with a unique time hopping
`sequence. Transfers would happen asynchronously with
`each node communicating with the base at any time using a
`unique hopping sequence without coordinating with other
`mobile devices.
`There are significant drawbacks to the TH-SSMA system
`for Supporting media stream transfers between devices of the
`network. This method is designed to link an external
`switched wireline network to mobile nodes, not as a method
`of implementing a network of interconnected wireless
`nodes. This method relies on the external ATM network to
`control the virtual path and virtual connections between
`devices. Base stations must be able to handle multiple
`simultaneous connections with mobile devices, each with a
`different time hopping sequence, adding enormously to the
`cost and complexity of the base station. Transfers between
`
`4
`mobile devices must travel through the base station using
`store and forward. Finally, all mobile nodes are asynchro
`nous, making truly isochronous transfers impossible.
`Accordingly, there is a need for a wireless communication
`network system apparatus which provides for isochronous
`data transfer between node devices of the network, which
`provides at least one master node device which manages the
`data transmission between the other node devices of the
`network, and which provides a means for reducing random
`errors induced by multipath fading, and which further pro
`vides communication protocol to provide a means for shar
`ing the transport medium between the node devices of the
`network so that each node device has a designated transmit
`time slot for communicating data. The present invention
`satisfies these needs, as well as others, and generally over
`comes the deficiencies found in the background art.
`
`BRIEF DESCRIPTION OF THE INVENTION
`
`The present invention is a wireless communication net
`work system for isochronous data transfer between node
`devices. In general, the network system comprises a plural
`ity of node devices, wherein each node device is a trans
`ceiver. Each transceiver includes a transmitter or other
`means, for transmitting data to the other transceivers as is
`known in the art. Each transceiver also includes a receiver
`or other means for receiving data from the other transceivers
`as is known in the art. One of the transceivers is preferably
`structured and configured as a “master” device. Transceivers
`other than the master device are structured and configured as
`“slave' devices. The master device carries out the operation
`of managing the data transmission between the node devices
`of the network system. The invention further provides means
`for framing data transmission and means for synchronizing
`the network.
`By way of example, and not of limitation, the data
`transmission framing means comprises a Medium Access
`Control protocol which is executed on circuitry or other
`appropriate hardware as is known in the art within each
`device on the network. The Medium Access Control proto
`col provides a Time Division Multiple Access (TDMA)
`frame definition and a framing control function. The TDMA
`architecture divides data transmission time into discrete data
`"frames'. Frames are further subdivided into “slots’. The
`framing control function carries out the operation of gener
`ating and maintaining the time frame information by delin
`eating each new frame by Start-Of-Frame (SOF) symbols.
`These SOF symbols are used by each of the slave devices on
`the network to ascertain the beginning of each frame from
`the incoming data stream.
`In the preferred embodiment, the frame definition com
`prises a master slot, a command slot, and a plurality of data
`slots. The master slot is used for controlling the frame by
`delineating the SOF symbols. As described in further detail
`below, the master slot is also used for synchronizing the
`network. The command slot is used for sending, requesting
`and authorizing commands between the master device and
`the slave devices of the network. The master device uses the
`command slot for ascertaining which slave devices are
`online, offline, or engaged in data transfer. The master
`device further uses the command slot for authorizing data
`transmission requests from each of the slave devices. The
`slave devices use the command slot for requesting data
`transmission and indicating its startup (online) or shutdown
`(offline) state. The data slots are used for data transmission
`between the node devices of the network. Generally, each
`transmitting device of the network is assigned one or more
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`corresponding data slots within the frame in which the
`device may transmit data directly to another slave device
`without the need for a “store and forward' scheme as is
`presently used in the prior art. Preferably, the master
`dynamically assigns one or more data slots to slave devices
`which are requesting to transmit data. Preferably, the data
`slots are structured and configured to have variable bit
`lengths having a granularity of one bit. The present inven
`tion provides that the master device need not maintain
`communication hardware to provide simultaneous open
`links between itself and all the slave devices.
`Broadcast is Supported with synchronization assured. This
`guarantees that media can be broadcast to many nodes at the
`same time. This method allows, for example, synchronized
`audio data to be sent to several speakers at the same time,
`and allows left and right data to be sent in the same frame.
`Asynchronous communication is allowed in certain slots
`of the frame through the use of either master polling or
`CSMA-CD after invitation from the master.
`The means for synchronizing the network is preferably
`provided by a clock master function in the master device and
`a clock recovery function in the slave devices. Each node
`device in the network system maintains a clock running at a
`multiple of the bit rate of transmission. The clock master
`function in the master device maintains a “master clock' for
`the network. At least once per frame, the clock master
`function issues a “master sync code' that is typically a
`unique bit pattern which identifies the sender as the clock
`master. The clock recovery function in the slave devices on
`the network carries out the operation of recovering clock
`information from the incoming data stream and synchroniz
`ing the slave device to the master device using one or more
`correlators which identifies the master sync code and a phase
`or delayed locked loop mechanism. In operation, the clock
`master issues a “master sync code once per frame in the
`“master slot'. A slave device trying to synchronize with the
`master clock will scan the incoming data stream for a master
`sync code using one or more correlators. As each master
`sync code is received, the phase or delayed locked loop
`mechanism is used to adjust the phase of the slave clock to
`that of the incoming data stream. By providing a common
`network clock on the master device, with slave devices
`synchronizing their local clocks to that of the master clock,
`Support for synchronous and isochronous communication in
`additional to asynchronous communication is provided.
`Time reference between all device nodes is highly accurate
`eliminating most latency and timing difficulties in isochro
`nous communication links.
`As noted above, each transceiver carries out the operation
`of transmitting and receiving data. In wireless transmission,
`data is transmitted via electromagnetic waves, which are
`propagated through free space. In the preferred embodiment,
`the invention provides data transmission via baseband wire
`less technology. This method uses short Radio Frequency
`(RF) pulses to spread the power across a large frequency
`band and as a consequence reduces the spectral power
`density and the interference with any device that uses
`conventional narrowband communication. This method of
`transmitting short pulses is also referred to as Ultra Wide
`Band technology. This present implementation provides
`baseband wireless transmission without any carrier. Use of
`baseband wireless greatly reduces multipath fading and
`provides a cheaper, easier to integrate solution by eliminat
`ing a sinewave carrier. According to the invention, there is
`no carrier to add, no carrier to remove, and signal processing
`may be done in baseband frequencies.
`
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`Additionally, using short pulses provides another advan
`tage over Continuous Wave (CW) technology in that mul
`tipath fading can be avoided or significantly reduced.
`The present invention further provides a modulator or
`other means for modulating data as is known in the art, a
`demodulator or other means for demodulating data as is
`known in the art, and a gain controller or other means for
`controlling the gain of each of the transceivers. In the
`preferred embodiment, the means for modulating data com
`prises a modulator which converts the TDMA frames into
`streams of baseband pulses. The means for demodulating
`data comprises a demodulator which converts incoming
`baseband pulses into TDMA frames.
`In a first embodiment, the invention provides pulse modu
`lation and demodulation with on/off keying. The transmit
`ting device modulates a “1” into a pulse. A “0” is indicated
`as the absence or lack of a pulse. The receiver locks on to the
`transmitted signal to determine where to sample in the
`incoming pulse streams. If a pulse appears where the signal
`is sampled, a “1” is detected. If no pulse appears, a “0” is
`detected.
`In another exemplary embodiment, the invention provides
`pulse modulation and demodulation using a pulse amplitude
`modulation scheme. Here, the transmitting device modulates
`a digital symbol as a pulse amplitude. For example, a three
`bit symbol can be represented with eight levels of pulse
`amplitude. The receiver locks on to the transmitted signal to
`determine where to sample the incoming pulse stream. The
`level of the pulse stream is sampled, and the pulse amplitude
`is converted to a digital symbol.
`The gain controlling means carries out the operation of
`adjusting the output gain of the transmitter and adjusting the
`input gain of the receiver.
`The network system also includes a hardware interface
`within the Data Link Layer of the Open Systems Intercon
`nection (OSI) Reference Model comprising a multiplexer/
`demultiplexer unit and a plurality of slot allocation units.
`The master devices described herein, in addition to car
`rying out its functions as a master device, may also carry out
`functions as a slave device as described above. For example,
`the master device may also engage in data transfer of
`non-protocol related data with a slave device.
`An object of the invention is to provide a baseband
`wireless network system which overcomes the deficiencies
`in the prior art.
`Another object of the invention is to provide a baseband
`wireless network system which provides isochronous data
`communication between at least two node devices on the
`network.
`Another object of the invention is to provide a baseband
`wireless network system which provides a master dev