[0001]
`
`This invention generally relates to networks of communications devices, in
`particular ultra wideband (UWB) communications devices.
`
`[0002]
`
`Techniques for UWB communication developed from radar and other military
`applications, and pioneering work was carried out by Dr G. F. Ross, as described
`in US3728632U.S. Pat. No. 3,728,632. Ultra-wideband communications systems
`employ very short pulses of electromagnetic radiation (impulses) with short rise
`and fall times, resulting in a spectrum with a very wide bandwidth. Some systems
`employ direct excitation of an antenna with such a pulse which then radiates with
`its characteristic impulse or step response (depending upon the excitation). Such
`systems are referred to as "“carrier free"” since the resulting rf emission lacks any
`well-defined carrier frequency. However other UWB systems radiate one or a few
`cycles of a high frequency carrier and thus it is possible to define a meaningful
`centre frequency and/or phase despite the large signal bandwidth.' The US Federal
`Communications Commission (FCC) defines UWB as a —10dB−10 dB bandwidth
`of at least 25% of a centre (or average) frequency or a bandwidth of at least
`1.5GHz1.5 GHz; the US DARPA definition is similar but refers to a —20dB−20
`dB bandwidth. Such formal definitions are useful and clearly differentiates UWB
`systems from conventional narrow and wideband systems but the techniques
`described in this specification are not limited to systems falling within this precise
`definition and may be employed with similar systems employing very short pulses
`of electromagnetic radiation.
`
`[0003]
`
`UWB communications systems have a number of advantages over conventional
`systems. Broadly speaking, the very large bandwidth facilitates very high data rate
`communications and since pulses of radiation are employed the average transmit
`power (and also power consumption) may be kept low even though the power in
`each pulse may be relatively large. Also, since the power in each pulse is spread
`over a large bandwidth the power per unit frequency may be very low indeed,
`
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`allowing UWB systems to coexist with other spectrum users and, in military
`applications, providing a low probability of intercept. The short pulses also make
`UWB communications systems relatively unsusceptible to multipath effects since
`multiple reflections can in general be resolved. Finally UWB systems lend
`themselves to a substantially all-digital implementation, with consequent cost
`savings and other advantages.
`
`Figure 1a[0004]
`
`FIG. 1 a shows a typical UWB transceiver 100. This comprises an transmit/receive
`antenna 102 with a characteristic impulse response indicated by bandpass filter
`(BPF) 104 (although in some instances a bandpass filter may be explicitly
`included), couples to a transmit/receive switch 106.
`
`[0005]
`
`The transmit chain comprises an impulse generator 108 modulatable by a baseband
`transmit data input 110, and an antenna driver 112. The driver may be omitted
`since only a small output voltage swing is generally required. One of a number of
`modulation techniques may be employed, typically either OOK (on-off keying i.e.
`transmitting or not transmitting a pulse), M-ary amplitude shift keying (pulse
`amplitude modulation), or PPM (pulse position modulation i.e. dithering the pulse
`position). Typically the transmitted pulse has a duration of <lns1 ns and may have
`a bandwidth of the order of gigahertz.
`
`[0006]
`
`The receive chain typically comprises a low noise amplifier (LNA) and automatic
`gain control (AGC) stage 114 followed by a correlator or matched filter (MF) 116,
`matched to the received pulse shape so that it outputs an impulse when presented
`with rf energy having the correct (matching) pulse shape. The output of MF 116 is
`generally digitised by an analogue-to-digital convertor (ADC) 118 and then
`presented to a (digital or software-based) variable gain threshold circuit 120, the
`output of which comprises the received data. The skilled person will understand
`that forward error correction (FEC) such as block error coding and other baseband
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`processing may also be employed, but such techniques are well-known and
`conventional and hence these is omitted for clarity.
`
`Figure lb[0007]
`
`FIG. 1 b shows one example of a carrier-based UWB transmitter 122, as described
`in more detail in USU.S. Pat. No. 6,026,125 (hereby incorporated by reference).
`This form of transmitter allows the UWB transmission centre frequency and
`bandwidth to be controlled and, because it is carrier-based, allows the use of
`frequency and phase as well as amplitude and position modulation. Thus, for
`example, QAM (quadrature amplitude modulation) or M-ary PSK (phase shift
`keying) may be employed.
`
`[0008]
`
`Referring to Figure lbFIG. 1 b, an oscillator 124 generates a high frequency carrier
`which is gated by a mixer 126 which, in effect, acts as a high speed switch. A
`second input to the mixer is provided by an impulse generator 128, filtered by an
`(optional) bandpass filter 130. The amplitude of the filtered impulse determines the
`time for which the mixer diodes are forward biased and hence the effective pulse
`width and bandwidth of the UWB signal at the output of the mixer. The bandwidth
`of the UWB signal is similarly also determined by the bandwidth of filter 130. The
`centre frequency and instantaneous phase of the UWB signal is determined by
`oscillator 124, and may be modulated by a data input 132. An example of a
`transmitter with a centre frequency of 1.5GHz1.5 GHz and a bandwidth of
`400MHz400 MHz is described in USU.S. Pat. No. 6,026,125. Pulse to pulse
`coherency can be achieved by phase locking the impulse generator to the oscillator.
`
`[0009]
`
`The output of mixer 126 is processed by a bandpass filter 134 to reject out-of-band
`frequencies and undesirable mixer products, optionally attenuated by a digitally
`controlled rf attenuator 136 to allow additional amplitude modulation, and then
`passed to a wideband power amplifier 138 such as a MMIC (monolithic
`microwave integrated circuit), and transmit antenna 140. The power amplifier may
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`be gated on and off in synchrony with the impulses from generator 128, as
`described in US'125U.S.'125, to reduce power consumption.
`
`Figure lc[0010]
`
`FIG. 1 c shows a similar transmitter to that of Figure ibFIG. 1 b, in which like
`elements have like reference numerals. The transmitter of Figure lcFIG. 1 c is,
`broadly speaking, a special case of the transmitter of Figure lbFIG. 1 b in which
`the oscillator frequency has been set to zero. The output of oscillator 124 of Figure
`lbFIG. 1 b is effectively a dc level which serves to keep mixer 126 always on, so
`these elements are omitted (and the impulse generator or its output is modulated).
`
`Figure ld[0011]
`
`FIG. 1 d shows an alternative carrier-based UWB transmitter 142, also described in
`US6U.S. Pat. No. 6,026,125. Again like elements to those of Figure lbFIG. 1 b are
`shown by like reference numerals.
`
`[0012]
`
`In the arrangement of Figure ldFIG. 1 d a time gating circuit 144 gates the output
`of oscillator 124 under control of a timing signal 146. The pulse width of this
`timing signal determines the instantaneous UWB signal bandwidth. Thus the
`transmitted signal UWB bandwidth may be adjusted by adjusting the width of this
`pulse.
`
`[0013]
`
`Ultra-wideband receivers suitable for use with the UWB transmitters of Figures
`lbFIGS. 1 b to ld1 d are described in USU.S. Pat. No. 5,901,172. These receivers
`use tunnel diode-based detectors to enable single pulse detection at high speeds
`(several megabits per second) with reduced vulnerability to in-band interference.
`Broadly speaking a tunnel diode is switched between active and inactive modes,
`charge stored in the diode being discharged during its inactive mode. The tunnel
`diode acts, in effect, as a time-gated matched filter, and the correlation operation is
`synchronised to the incoming pulses.
`
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`Figure le[0014]
`
`FIG. 1 e shows another example of a known UWB transmitter 148, as described
`for example in USU.S. Pat. No. 6,304,623 (hereby incorporated by reference). In
`Figure leFIG. 1 e a pulser 150 generates an rf pulse for transmission by antenna
`152 under control of a timing signal 154 provided by a precision timing generator
`156, itself controlled by a stable timebase 158. A code generator 160 receives a
`reference clock from the timing generator and provides pseudo-random time offset
`commands to the timing generator for dithering the transmitter pulse positions.
`This has the effect of spreading and flattening the comb-like spectrum which
`would otherwise be produced by regular, narrow pulses (in some systems
`amplitude modulation may be employed for a similar effect).
`
`Figure if[0015]
`
`FIG. 1 f shows a corresponding receiver 162, also described in US'623U.S.'623.
`This uses a similar timing generator 164, timebase 166 and code generator 168
`(generating the same pseudo-random sequence), but the timebase 166 is locked to
`the received signal by a tracking loop filter 170. The timing signal output of timing
`generator 164 drives a template generator 172 which outputs a template signal
`matching the transmitted UWB signal received by a receive antenna 174. A
`correlator/sampler 176 and accumulator 178 samples and correlates the received
`signal with the template, integrating over an aperture time of the correlator to
`produce an output which at the end of an integration cycle is compared with a
`reference by a detector 180 to determine whether a one or a zero has been received.
`
`Figure 1g[0016]
`
`FIG. 1 g shows another UWB transceiver 182 employing spread spectrum-type
`coding techniques. A similar transceiver is described in more detail in USU.S. Pat.
`No. 6,400,754 the contents of which are hereby explicitly incorporated by
`reference.
`
`[0017]
`
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`In FigureFIG. 1 g a receive antenna 184 and low noise amplifier 186 provide one
`input to a time-integrating correlator 188. A second input to the correlator is
`provided by a code sequence generator 190 which generates a spread spectrum-
`type code such as a Kasami code, that is a code with a high auto-correlation
`coefficient from a family of codes with no low cross-correlation coefficients.
`Correlator 188 multiplies the analogue input signal by the reference code and
`integrates over a code sequence period and in US U.S.'754 is a matched filter with
`a plurality of phases representing different time alignments of the input signal and
`reference code. The correlator output is digitised by analogue-to-digital converter
`192 which provides an output to a bus 194 controlled by a processor 196 with
`memory 198 the code sequence generator 190 is driven by a crystal oscillator
`driven flock 200 a transmit antenna driver 202 receives data from bus 194 which is
`multiplied by a code sequence from generator 190 and transmitted from transmit
`antenna 204. In operation coded sequences of impulse doublets are received and
`transmitted, in one arrangement each bit comprising a 1023-chip sequence of
`lOns10 ns chips, thus having a duration of 10μs 10 μs and providing 30dB30 dB
`processing gain. Shorter spreading sequences and/or faster clocks may be
`employed for higher bit rates.
`
`[0018]
`
`The transceiver described in US U.S.'754 uses a modification of a frequency-
`independent current-mode shielded loop antenna (as described in USU.S. Pat. No.
`4,506,267) comprising a flat rectangular conducting plate. This antenna is referred
`to as a large-current radiator (LCR) antenna and when driven by a current it
`radiates outwards on the surface of the plate.
`
`Figure lh[0019]
`
`FIG. 1 h shows a driver circuit 206 for such an LCR transmit antenna 208. The
`antenna is driven by an H-bridge comprising four MOSFETs 210 controlled by left
`(L) and right (R) control lines 212, 214. By toggling line 214 high then low whilst
`maintaining line 214 low an impulse doublet (that is a pair of impulses of opposite
`polarity) of a first polarity is transmitted, and by toggling line 212 high then low
`whilst holding line 214 low an impulse doublet of opposite polarity is radiated. The
`
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`antenna only radiates whilst the current through it changes, and transmits a single
`gaussain impulse on each transition.
`
`Figures 2a[0020]
`
`FIGS. 2 a to 2h2 h show examples UWB waveforms. Figure 2aFIG. 2 a shows a
`typical output waveform of a UWB impulse transmitter, and Figure lbFIG. 1 b
`shows the power spectrum of the waveform of Figure 2a. Figure 2cFIG. 2 a. FIG. 2
`c shows a wavelet pulse (which when shortened becomes a monocycle) such as
`might be radiated from one of the transmitters of Figures lbFIGS. 1 b to Id. Figure
`2d1 d. FIG. 2 d shows the power spectrum of Figure 2c. Figure 2eFIG. 2 c. FIG. 2 e
`shows an impulse doublet and Figure 2fFIG. 2 f the power spectrum of the doublet
`of Figure 2eFIG. 2 e. It can be seen that the spectrum of Figure 2fFIG. 2 f
`comprises a comb with a spacing.( (in frequency) determined by the spacing (in
`time) of the impulses of the doublet. and an overall bandwidth determined by the
`width of each impulse. It can also be appreciated from Figures 2eFIGS. 2 e and 2f2
`f that dithering the pulse positions will tend to reduce the nulls of the comb
`spectrum. Figure 2gFIG. 2 g shows examples of basis impulse doublet waveforms
`for a logic 0 and a logic 1. Figure 2hFIG. 2 h shows an example of a TDMA UWB
`transmission such as might be radiated from the transceiver of FigureFIG. 1 g, in
`which bursts of Code Division Multiple access (CDMA) -)-encoded data are
`separated by periods of non-transmission to allow access by other devices.
`
`[0021]
`
`Ultra wideband communications potentially offer significant advantages for
`wireless home networking, particularly broadband networking for audio and video
`entertainment devices, because of the very high data rates which are possible with
`UWB systems. However, UWB communications also present a number of special
`problems, most particularly the very low transmit power output imposed by the
`relevant regulatory authorities, in the US the FCC. Thus the maximum permitted
`power output is presently below the acceptable noise floor for unintentional
`emitters so that a UWB signal effectively appears merely as noise to a
`conventional receiver. This low power output limits the effective range of UWB
`communications and there is therefore a need to address this difficulty.
`
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`[0022]
`
`The applicant has recognised that there are some features of UWB communications
`of which advantage can be taken to address this difficulty, in particular the ability
`of UWB to support multiple channels. Such multiple channels may be provided in
`a number of ways. For example the psudo-random code used in the transmitters
`described above with reference to figures leFIGS. 1 e and 1 g may be employed to
`define code division multiplexed channels in a UWB communications system.
`Alternatively an arrangement such as that described with reference to figure lbFIG.
`1 b may be employed to define a plurality of UWB bands. In another approach the
`relative timing of impulse doublets in an antipodeal modulation scheme may be
`whitened or spread using a psudo-random noise (pn) sequence code, again the pn
`sequence defining a channel. Provided that the impulse doublets are well separated
`so that the mark:space ratio is small collisions are relatively rare and generally only
`result in correctable single bit errors, so that multiple channels can coexist within
`one broad. UWB band.
`
`[0023]
`
`The ability of UWB communications to support such multiple channels facilitates
`the implementation of a mesh-type network in which when one UWB device is out
`of range with another (or at least sufficiently out of range that communication at a
`desired speed or with a desired quality/bit error rate) communication takes place
`via a third, intermediary UWB device within range of both the first and second
`device.
`
`[0024]
`
`In a conventional radio network such as a network based upon a standard in the
`IEEE802.11 series communications between devices in the network are routed
`through a central base station which stores a routing table defining the topology of
`the entire network so that routing within the network can be controlled. However
`such an arrangement suffers from a number of defects in a wireless home
`networking environment, one important defect being the need to reconfigure the
`base station routing table whenever the network configuration changes. In a home
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`environment it is undesirable to have to configure a router when the network
`topology changes, particularly as devices may be frequently added to or removed
`from the network, for example simply by switching on and off a network-enabled
`television or video recorder.
`
`[0025]
`
`Furthermore the base station of such a network constitutes a single point of failure
`of the network, which again is undesirable. A still further difficulty is the relatively
`large memory and processing requirements of current network protocols — —
`typically equivalent computing power to a 500 megahertz Pentium (trademark) is
`required to implement a networking protocol of this type, whereas an integrated
`circuit to enable wireless home networking should preferably retail in quantity for
`under $10.
`
`[0026]
`
`According to a first aspect of the present invention, there is therefore provided an
`ultra-wideband (UWB) network comprising a plurality of UWB devices each
`forming a node of said network, pairs of said UWB devices being configured for
`communication with one another using one of a plurality of UWB channels, each
`said UWB device comprising a UWB transceiver for bidirectional communication
`over one or more of said UWB channels with at least one other of said UWB
`devices; and a device
`controller coupled to said UWB transceiver, said controller being configured to
`determine a said UWB channel for use in establishing a communication link with
`each other UWB device; whereby said network is configured for automatic
`construction of a set of communications links between said nodes of said network.
`
`[0027]
`
`In embodiments employing UWB channels to establish communication links
`within the network this effectively allows the construction of virtual circuits within
`the network for communication between nodes. Thus where first and second
`devices are communicating via an intermediary the intermediary can communicate
`
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`with the first device using a first channel and with the second device using a
`second channel, the intermediary acting as a store and forward node for data
`communicated between the first and second devices. In this way the intermediary
`need only be locally aware — —that is no single device requires a map of the
`global network structure (or changes in this) because routing can be performed
`without such a map. Each intermediary device merely knows that incoming data on
`one channel (and/or port) should be forwarded on a second channel and/or port),
`such a list of associated channels being locally stored, for example as a table. In
`this way data is forwarded through the network until reaching its intended
`recipient.
`
`[0028]
`
`To determine the data for these locally stored tables a broadcast protocol may be
`employed, for example a first device broadcasting a connection request to a second
`device throughout the network, the second device responding when it receives the
`connection request. Thus each device is preferably configured for broadcasting
`such a connection request, that is for forwarding the connection request to
`substantially all other nodes within range except that from which the request was
`received. The skilled person will recognise that such a technique has the potential
`to consume a significant fraction of the network bandwidth. However, the
`technique is practical in wireless home networks because such networks are
`generally relatively small and thus broadcast traffic, overall, need not have a great
`impact upon network availability.
`
`[0029]
`
`A similar broadcast arrangement can be employed to alert devices within the
`network when a new device connects, for example when a network-enabled
`television is switched on. This initial broadcast can also be used to determine a
`unique identifier for the new device within the network such as a device name
`and/or address.
`
`[0030]
`
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`

`The skilled person will recognise that one characteristic of embodiments of the
`above described networks is their essentially local routing — —messages are sent
`between devices along a chain of devices in whichever direction the message is
`sent, and thus although virtual circuits or connections are established between
`devices this is done dynamically, by means of local routing tables, rather than by
`some overall master. More particularly in embodiments a routing table entry for a
`device defines two connections, one for the link for the connection to the device,
`the second for the link for the connection from the device (for one-way
`communication only one of these links need be defined). Optionally the routing
`table may further include, for each link defined by a pair of channels for incoming
`and outgoing data, an identifier for the intended end recipient, although in
`embodiments this is not necessary because a message containing an identifier for
`the intended recipient is always forwarded (if it can be) unless the node is in fact
`the recipient.
`
`[0031]
`
`With embodiments of the above protocols the time to set up a virtual connection is
`relatively small compared with typical data transmission times and it is therefore
`practicable to tear down and replace virtual connections when necessary, for
`example when a connection is found to be broken because a node in a chain is no
`longer responding. A virtual connection may be removed, for example, by marking
`an entry in a local link table as available for reuse; alternatively an entry may be
`deleted. Such an amendment to a local link table may be made, for example, when
`a message cannot be forwarded because the recipient is not found or does not
`respond/acknowledge receipt. In such a case a disconnect message is preferably
`sent back to the originator of the undelivered message so that the link table of each
`link in the chain can be updated to remove the connection and free up memory for
`reuse.
`
`[0032]
`
`Preferably, in the above described networks two types of channel are provided, a
`"“physical"” channel such as a UWB code channel in a CDMA based scheme, and
`a logical channel. A plurality of logical channels may be associated with a single
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`physical channel and the physical channel may then define a domain of the
`network, such as a piconet.
`
`[0033]
`
`A single UWB channel may be used for bidirectional communication, for example
`by time-multiplexing, or one channel may be used for communications in a
`forward direction and one channel for communications in a reverse direction. It
`will also be appreciated that more than one channel may be employed for a link
`between two network nodes for increased data rates.
`
`[0034]
`
`In a related aspect the invention provides an ultra-wideband (UWB) network
`comprising a plurality of UWB devices each forming a node of said network, pairs
`of said UWB devices being configured for communication with one another using
`one of a plurality of UWB channels, each said UWB device comprising a UWB
`transceiver for bidirectional communication over a plurality of said UWB channels
`with a plurality of other UWB devices; and a connection table configured to store
`connection data associating a first of said channels bearing incoming data with a
`second of said channels for use in forwarding said incoming data to another of said
`UWB devices.
`
`[0035]
`
`To facilitate forwarding data in such a UWB network which, as previously
`mentioned, may operate at very high speeds, packet data communication is
`preferably employed. Broadly speaking a conventional packet structure may be
`used but preferably with the addition of a channel identifier to facilitate rapid
`processing of packets and, in particular, to facilitate rapid routing of a packet
`within a node, for example for forwarding.
`
`[0036]
`
`In a further aspect, therefore, the invention provides a data packet for UWB
`communication between nodes of a packet data UWB network, such as a network
`
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`

`described above, the network having a plurality of UWB channels for
`communication between said network nodes, said data packet including payload
`data and UWB channel identification data, such as a channel number, whereby a
`said network node receiving said data packet is able to determine a UWB channel
`to use when forwarding said data packet.
`
`[0037]
`
`As previously described there are preferably two kinds of channel operating: (i) a
`'UWB‘UWB Code Channel'Channel’ which is used to distinguish between
`different concurrent radio networks (piconets) along CDMA lines; and (ii) a
`channel or channels for logical communication flow within the network. The
`CDMA code may be known, in order to receive a packet, but there may be several
`concurrent logical channels on any given single CDMA domain, either due to a
`QoS (quality of service) distinction such as bandwidth or latency control, or simply
`because there are multiple devices sharing the same CMDA domain by means of
`time multiplexing. For this reason a network packet preferably includes some form
`of logical routing information, which may be derived, from example, from paired
`MAC addresses in an 802.3 style Ethernet frame or by means of a (proprietary)
`header word.
`
`[0038]
`
`In a further related aspect the invention provides an ultra-wideband (UWB) device
`for a node of a UWB network, the device comprising an interface to a UWB
`transceiver for bidirectional communication over one or more UWB channels with
`one or more other UWB devices; and a controller coupled to said UWB transceiver
`interface, said controller being configured to control said UWB transceiver to
`communicate with said one or more other UWB devices to determine a said UWB
`channel to employ for communicating with each of said other UWB devices.
`
`[0039]
`
`In another aspect the invention provides a controller for controlling a UWB device
`for a node of a UWB network, the UWB device including a UWB transceiver for
`
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`bidirectional communication over one or more UWB channels with a plurality of
`other network devices, communication with at least one indirectly linked device of
`said other UWB devices being via an intermediary UWB device, the controller
`comprising an interface for said UWB transceiver; data memory for storing
`network comniunicationcommunication link connection data comprising data
`associating each said network device with a said UWB channel; program memory
`storing computer program code; and a processor coupled to said interface, said data
`memory, and to said program memory for loading and implementing said program
`code; wherein said connection data for said indirectly linked UWB device
`comprises data associating said indirectly linked device with a channel for
`communicating with said intermediary device; and wherein said code comprises
`code to send network data to said indirectly linked device by accessing said
`connection data for said indirectly linked device to determine said channel
`associated with said intermediary device, and controlling said UWB transceiver to
`transmit said network data over said determined channel.
`
`[0040]
`
`The invention further provides a controller for an ultra-wideband (UWB) network
`node, the controller comprising a processor having a processor control bus and a
`processor data bus; processor memory coupled to said processor data bus; buffer
`memory coupled to a second data bus; a memory access controller coupled to said
`second data bus and to said processor control bus; and a UWB interface for
`interfacing to a UWB communications device, coupled to said processor control
`bus and to said second data bus; and wherein said processor is master of said
`processor control bus and said memory access controller is master of said second
`data bus.
`
`[0041]
`
`The above described architecture facilitates the rapid processing of data packets
`sent over the network and, in embodiments, is also relatively inexpensive to
`implement. Preferably a link is also provided from the processor memory to the
`second data bus so that data, for example header data from a packet, may be
`transferred to the processor memory and/or a cache. In embodiments one or more
`
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`

`further physical network layer interfaces may be provided, also coupled to the
`processor control bus and to the second data bus. These may comprise, for
`example, a PCI (peripheral component interconnect) interface and/or an Ethernet
`interface and/or a further UWB interface.
`
`[0042]
`
`In preferred embodiments of the controller the memory access controller is the sole
`master of the second data bus so that there is no need for arbitration on this bus. It
`is further preferable that the buffer memory is coupled to the second data bus via
`the memory access controller. In this way the memory access controller controls all
`access to and from the buffer memory. The memory access controller is itself
`under control of the processor, which preferably is the sole master of the processor
`control bus. This decouples data processing functions from the very rapid
`movement of data from the UWB interface to the buffer memory and, if necessary,
`out again for retransmission, and thus facilitates very high data rate data handling.
`In a preferred embodiment the memory access controller has one or more
`associated registers and is configured to store control information from packets
`passing through the controller in these registers for reading by the processor. This
`further facilitates rapid packet handling.
`
`[0043]
`
`In another aspect the invention provides a UWB network having a mesh topology
`and comprising a plurality of UWB devices configured for mutual UWB
`communication with one another, a first of said devices being configured for
`communicating with a second of said devices via a third of said devices when said
`second device is out of range, and wherein said third device is configured to use a
`first UWB communication channel for communicating with said first UWB device
`and a second UWB communication channel for communicating with said second
`UWB device.
`
`[0044]
`
`Sonos Ex. 1014, p. 15
` Sonos v. Google
` IPR2021-00964
`
`

`

`The invention further provides a method of sending data from a first data processor
`to a second data processor in a network of data processors having a variable
`network topology, said topology being defined by communications links between
`processors of said network, the method comprising broadcasting a connection
`request message from said first processor to substantially all other processors to
`which it is linked; receiving a connection established message from said second
`data processor via an intermediary processor with which said first processor is
`linked; and sending said data to said intermediary processor for forwarding to said
`second processor.
`
`[0045]
`
`The invention further provides processor control code to implement the above
`described networks, d