Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
  • H04W16/14—Spectrum sharing arrangements between different networks
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/12—Wireless traffic scheduling
  • H04W72/1215—Wireless traffic scheduling for collaboration of different radio technologies
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
  • H04W4/80—Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
  • H04W84/04—Large scale networks; Deep hierarchical networks
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/18—Self-organising networks, e.g. ad-hoc networks or sensor networks

Definitions

• the invention relates to interoperability and coexistence mechanisms in a communication system integrating two different wireless radio systems. More particularly, the invention provides a method and system for minimizing or preventing local and network interference while transmitting and receiving addressed packets between two disparate wireless services (e.g., Bluetooth and IEEE 802.11) by providing real-time hardware-based signaling interfaces.
• two disparate wireless services e.g., Bluetooth and IEEE 802.11
• Wireless systems typically operate in a common medium - the air.
• frequency bands are typically assigned for operation by particular wireless systems.
• wireless systems are very popular, and thus most useable frequency bands are already assigned.
• higher and higher frequencies are becoming more and more useful.
• WiFi wireless local area network
• BluetoothTM a quickly emerging wireless piconet system
• WiFi Wireless Fidelity
• IEEE 802.11 is a standard for wireless systems that operates in the 2.4-2.5 GHz ISM (industrial, scientific and medical) band.
• This ISM band is available world-wide and allows unlicensed operation for spread spectrum systems.
• the 2,400-2,483.5 MHz band has been allocated, while for some other countries, such as Japan, another part of the 2.4-2.5 GHz ISM band has been assigned.
• the 802.11 standard focuses on the MAC (Medium Access Control) protocol and PHY (Physical Layer) protocol for Access Point (AP) based networks and ad-hoc networks.
• Access Point based networks the stations within a group or cell can communicate only directly to the Access Point. This Access Point forwards messages to the destination station within the same cell or through a wired distribution system to another Access Point, from which such messages arrive finally at the destination station.
• the stations operate on a peer-to-peer level and there is no Access Point or (wired) distribution system.
• the 802.11 standard supports: DSSS (direct sequence spread spectrum) with differential encoded BPSK and QPSK; FHSS (Frequency Hopping Spread Spectrum) with GFSK (Gaussian FSK); and infrared with PPM (Pulse Position Modulation). These three physical layer protocols (DSSS, FHSS, and infrared) all provide bit rates of 2 and 1 Mbit/s.
• the 802.1 1 standard further includes extensions 11a and 11 b.
• Extension 11 b is for a high rate CCK (Complementary Code Keying) physical layer protocol, providing bit rates 11 and 5.5 Mbit/s as well as the basis DSSS bit rates of 2 and 1 Mbit/s within the same 2.4-2.5 GHz ISM band.
• Extension 11a is for a high bit rate OFDM (Orthogonal Frequency Division Multiplexing) physical layer protocol standard providing bit rates in the range of 6 to 54 Mbit/s in the 5 GHz band.
• OFDM Orthogonal Frequency Division Multiplexing
• the 802.11 basic medium access behavior allows interoperability between compatible physical layer protocols through the use of the CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) protocol and a random back-off time following a busy medium condition.
• all directed traffic uses immediate positive acknowledgement (ACK frame), where a retransmission is scheduled by the sender if no positive acknowledgement is received.
• ACK frame immediate positive acknowledgement
• the 802.1 1 CSMA/CA protocol is designed to reduce the collision probability between multiple stations accessing the medium at the point in time where collisions are most likely to occur. The highest probability of a collision occurs just after the medium becomes free, following a busy medium. This is because multiple stations would have been waiting for the medium to become available again. Therefore, a random back-off arrangement is used to resolve medium contention conflicts.
• the 802.11 MAC defines: special functional behavior for fragmentation of packets; medium reservation via RTS/CTS (Request-To- Send/Clear-To-Send) polling interaction; and point co-ordination (for time- bounded services).
• the IEEE 802.11 MAC also defines Beacon frames, sent at a regular interval by an AP to allow Stations (STAs) to monitor the presence of the AP. IEEE 802.11 also defines a set of management frames including Probe Request frames which are sent by an STA, and are followed by Probe Response frames sent by the AP. Probe Request frames allow an STA to actively scan whether there is an AP operating on a certain channel frequency, and for the AP to show to the STA what parameter settings this AP is using.
• Bluetooth allows for the replacement of the many proprietary cables that connect one device to another with one universal short-range radio link.
• Bluetooth radio technology built into both a cellular telephone and a laptop would replace the cumbersome cable used today to connect a laptop to a cellular telephone.
• Printers, Personal Digital Assistant's (PDA's), desktops, computers, fax machines, keyboards, joysticks and virtually any other digital device can be part of the Bluetooth system.
• PDA's Personal Digital Assistant's
• desktops computers, fax machines, keyboards, joysticks and virtually any other digital device can be part of the Bluetooth system.
• Bluetooth radio technology provides a universal bridge to existing data networks, a peripheral interface, and a mechanism to form small private ad-hoc groupings of connected devices away from fixed network infrastructures.
• the Bluetooth radio system uses a fast acknowledgement and frequency hopping scheme to make the link robust.
• Bluetooth radio modules avoid interference from other signals by hopping to a new frequency after transmitting or receiving a packet.
• the Bluetooth radio system typically hops faster and uses shorter packets.
• Short packets and fast hopping also limit the impact of domestic and professional microwave ovens.
• Use of Forward Error Correction (FEC) limits the impact of random noise on long-distance links.
• FEC Forward Error Correction
• the encoding is optimized for an uncoordinated environment. Bluetooth radios operate in the unlicensed ISM band at 2.4 GHz. A frequency hop transceiver is applied to combat interference and fading.
• a shaped, binary FM modulation is applied to minimize transceiver complexity.
• the gross data rate is 1 Mb/s.
• a Time-Division Duplex scheme is used for full-duplex transmission.
• the Bluetooth baseband protocol is a combination of circuit and packet switching. Slots can be reversed for synchronous packets. Each packet is transmitted in a different hop frequency. A packet nominally covers a single slot, but can be extended to cover up to five slots.
• Bluetooth can support up to seven simultaneous asynchronous data channels, up to three simultaneous synchronous voice channels, or a channel that simultaneously supports asynchronous voice. Each voice channel supports 64 kb/s synchronous (voice) link.
• the asynchronous channel can support an asymmetric link of maximally 721 kb/s in either direction while permitting 57.6 kb/s in the return direction, or a 432.6 kb/s symmetric link.
• the IEEE 802.11 standard is already well-established, with local area networks implemented based on the standard. However, as Bluetooth emerges in the market, it is likely to be implemented in a domestic environment for communications within the home. Since both Bluetooth and IEEE 802.11 both operate in the 2.4
• Co-location is defined as having the transmitters, receivers, and antennas physically close together with poor isolation. This occurs when, e.g., they are both physically inside the same PC, or other similar product.
• someone with a lap-top computer may wish to connect to a IEEE 802.11 wireless local area network in the workplace, and connect to a device, such as a mobile telephone, using a Bluetooth interface outside of the workplace.
• WiFi and Bluetooth do not operate at identical frequencies, they are close enough in frequency that interference becomes an issue when placed in close proximity to one another.
• a method is provided to avoid transmission interference between a first wireless system operating at a first range of frequencies of operation and a second wireless system operating at a second range of frequencies of operation.
• the first wireless system and the second wireless system are co-located.
• Radio status information is passed from the first wireless system to the second wireless system. Transmission by the second radio system is delayed based on medium status information provided by the first wireless system.
• One of the first wireless system and the second wireless system transmits in RF time slots. Concurrent radio transmission by both the first wireless system and the second wireless system are avoided.
• a method and apparatus incorporates a first wireless system operating at a first range of frequencies of operation and a second wireless system operating at a second range of frequencies of operation.
• the first wireless system and the second wireless system are co-located.
• a first busy signal is provided by the first wireless system to the second wireless system over a direct communication link indicating a timing of a reception on the first wireless system.
• a second busy signal provided by the second wireless system to the first wireless system over a direct communication link indicates a timing of a reception on the second wireless system.
• a controller is responsive to the first busy signal. The controller is configured to cause the second wireless system to delay transmission due to an active transmission state of the first wireless system.
• One of the first wireless system and the second wireless system transmits in RF time slots.
• Fig. 1 shows a block diagram of one embodiment of a direct communication link established between two co-located wireless services, e.g., a Bluetooth system and an WiFi (IEEE 802.1 1 ), in accordance with the principles of the present invention.
• Fig. 2 shows exemplary signal timing of an exemplary WLAN
• WLMBsy Medium Busy
• Fig. 3 shows timing of an exemplary Bluetooth BTMBsy signal while operating in asynchronous mode, in accordance with the principles of the present invention.
• Fig. 4 shows exemplary synchronous signal timing of a Bluetooth BTSYNC signal, in accordance with the principles of the present invention.
• Fig. 5 shows characteristics of an exemplary BTDATAVALID signal, in accordance with the principles of the present invention.
• Fig. 6 shows characteristics of an exemplary BTDATAVALID signal indicating when IEEE 802.11 (WiFi) data is valid, in accordance with the principles of the present invention.
• Fig. 7 shows an exemplary IEEE 802.11 radio system and Bluetooth baseband equipment including an exemplary hard-wired interface (e.g., a 2-wire interconnect), in accordance with the principles of the present invention.
• the present invention provides communication between disparate wireless services, e.g., an IEEE 802.11 MAC (Wireless LAN MAC or WMAC) and a Bluetooth Baseband/MAC, to inform the other regarding radio status, facilitating operable coexistence between the two technologies.
• the communication between the co-located wireless services avoids the condition that one wireless service would be transmitting at the same time that another co-located wireless service is receiving.
• direct communication between the two wireless service front ends may be coordinated and planned in an RF time slot wireless system such as a piconet, to avoid the condition where one wireless service will need to receive while the other is transmitting.
• the present invention provides real-time hardware-based signaling interfaces between two co-located disparate wireless services, such as Bluetooth and IEEE 802.11. This hard-wired interface is provided to allow each service to inform the other of the active state of it's radio front end.
• a bi-directional or shared resource such as a mailbox is employed to pass local messages containing real-time status information to the other wireless service, again allowing coordination and avoidance of the undesirable condition of one wireless service transmitting while the other is receiving.
• Direct communication between the wireless services allows control of data transmissions from the respective wireless services, and provides a way to minimize and even prevent entirely local and network interference while transmitting and receiving addressed packets within each of the two disparate services.
• the present invention includes improvements over published US Patent Application 2001/10689 A1 to Awater et al., the entirely of which is expressly incorporated herein by reference. Assuming close proximity, it has been demonstrated through analytical and laboratory analysis that having either system transmit during periods of active reception of the other service tends to seriously degrade the throughput of the other service in the best case, and in some worst case situations renders the system completely un-useable for some period of time.
• This invention provides a method to resolve basic coexistence issues by preventing local and remote TX interference while receiving or transmitting addressed packets between two disparate services (Bluetooth (BT) and IEEE 802.1 1 (WLAN)).
• Bluetooth Bluetooth
• WLAN IEEE 802.1 1
• a further embodiment provides a shared resource that provides the ability to effectively pass relevant system information between the two entities.
• One goal of the system design is to allow each service to approach the data rates and latencies defined by each individual specification. However, since there will be periods in time that both services will require bandwidth at the same or very similar frequencies, communication between the two co-located services can decrease the interference seen in the RF domain. The passing of mode of operation information, time slot information, schedule information, and/or realtime status information can be used by both services to adequately make decisions about the instantaneous use of the frequency band.
• the other service can be local, or it can be remote yet closely located.
• the Bluetooth wireless service or device informs the co-located other wireless service when Bluetooth receive (RX) slots (and even transmit (TX) slots) are planned to occur.
• RX Bluetooth receive
• TX transmit
• both Bluetooth's synchronous connection-oriented link (SCO) and asynchronous connectionless link (ACL) are implemented, though it should be noted that WLAN and slave-side Asynchronous BT cannot provide definitive information when a message will be received.
• scheduling can be implemented in the other wireless service such that a transmission (TX) slot can be prevented in the WLAN when the RF time slot of the other wireless service is receiving.
• mechanisms are employed that preferably attempt to avoid or defer transmission on one service while a receive RX slot is in progress in the other service. For the purposes of efficiency, it is preferred that transmission be deferred by the one service when receive traffic is actually addressed to the other service.
• IEEE 802.11 and Bluetooth services are able to transmit simultaneously under most circumstances, as well as receive simultaneously under most circumstances.
• some applications may require the suppression of simultaneous 'transmits' from both services.
• a hard-wired interface e.g., a 2-wire interface
• a hard-wired interface e.g., a 2-wire interface
• IEEE 802.11 and BT coexist in a communications system but are not collocated on the same PCB- i.e. separate boards in the system with a defined interconnect through a specified interface such as an edge connector.
• the simple two-wire interface could also be leveraged in a similar manner when 802.11 and BT are co-located on the same PCB by running PCB traces.
• Fig. 7 shows an exemplary IEEE 802.11 radio system 100 and Bluetooth baseband equipment 150 including an exemplary hard-wired interface (e.g., a 2-wire interconnect), in accordance with the principles of the present invention.
• the co-existing wireless systems 100, 150 include a direct communication link therebetween comprising Bluetooth Medium Busy (BTMBsy) and WLAN Medium Busy (WLMBsy) signals.
• BTMBsy Bluetooth Medium Busy
• WLMBsy Wireless Medium Busy
• a shared resource such as a mailbox allows the disparate wireless services to pass local messages back and forth between the disparate services.
• General timing, QoS state, mode of operation, frequency hopping information, channel selection information, and application information, 802.11 channel information, and general device state information may be shared between the services.
• BT knows in advance when TX and RX will happen, because of its RF time slot time division nature.
• a WLAN interface can be provided with critical information on when an RF time slot wireless service such as Bluetooth will access its media (i.e., when BT requires reception of an incoming frame, when it will transmit, how long it will require the media to be busy, etc.)
• the wireless services may interrupt one another using the direct communication link (e.g., direct-wire interface, mailbox, etc.)
• the direct communication link may also be used to provide information relating to a timing reference point.
• the direct communication link may also be used to provide a dynamic exchange of information sufficient to allow one wireless service (e.g., a Bluetooth system) to adaptively frequency hop around radio frequency (RF) channels of another wireless service (e.g., a WLAN) as they are transmitted by the WLAN system.
• one wireless service e.g., a Bluetooth system
• RF radio frequency
• Fig. 1 shows a block diagram of one embodiment of a direct communication link established between two co-located wireless services, e.g., a Bluetooth system and an WiFi (IEEE 802.1 1 ), in accordance with the principles of the present invention.
• a Bluetooth system e.g., a Bluetooth system
• WiFi IEEE 802.1 1
• an IEEE 802.11 MAC 100 includes WMAC 110, GPIO (General Purpose Input/Output interface) 120 and memory interface 130.
• the Bluetooth (BT) baseband equipment 150 includes CPU 180, GPIO 160 memory 170.
• the direct communication link comprises a 2-wire interface with two dedicated "xMBsy" signals.
• the first, “Bluetooth Medium Busy” signal BTMBsy indicates when the Bluetooth system is actually receiving a packet over its medium.
• the second signal “WLAN Medium Busy” WLMBsy indicates when the IEEE 802.1 1 WLAN is actually receiving a packet over its medium.
• Busy signals set up to inform when they are receiving may additionally be used to indicate when they are transmitting, in accordance with the principles of the present invention.
• an event interface may be used to convey that information has been written into the shared resource.
• the shared resource forms a direct communication link that passes local messages back and forth between the disparate wireless services.
• the external event mechanism may be used as a timing reference point.
• a mailbox interface can be used to convey, among other important system parameters, "No-TX Timing Window” or “No-RX Timing Window” information. This information can be shared with the WLAN system in an effort to coordinate and defer WLAN transmission during periods of known reception on the BT link. To support this mailbox a stable timing reference is required and the proposed BTSYNC signal would be the required signal to provide that stable timing source.
• the shared resource is shown as being embedded in the BT transceiver. In actuality it could be located anywhere within the "local" communications system.
• the interface depicted in Figure 1 , provides two dedicated "xMBusy” signals, a pair of even signals, and a synchronization signal.
• the definition of these pins is:
• the WMAC can generate WLMBsy when RX frames are coming in or it is transmitting frames on the media and further can be assumed that the WMAC can also negate or turn this signal off when the IEEE 802.11 -defined A1 address field says that our station is not being currently addressed (i.e. no address match, broadcast, or multi-cast packet).
• the Bluetooth transmitter should defer and not actively transmit data out onto the BT medium while this signal is active. This ultimately may introduce some issues with BT link synchronization and accordingly the deferral mechanisms may be made provisional depending on current mode, and possibly how much the BT transmitter has already deferred.
• rate reduction techniques may be preferred on the
• the BT service can make intelligent choices as to when to ignore this signal and transmit anyway. For instance, when BT is in a quality of service (QoS) link, adherence to the QoS parameters may necessitate the transmission of BT packets at a particular instance in time regardless of the state of the 802.11 receiver.
• QoS quality of service
• the WLMBsy signal is driven high when the IEEE 802.11 receiver indicates a busy medium (e.g., transmitting OR receiving). Conversely, this signal should be driven low when the medium is clear.
• Fig. 2 shows exemplary signal timing of an exemplary WLAN
• WLMBsy Medium Busy
• forward IEEE 802.11 packet includes a preamble 210, a PLCP header 220, a MAC header 230, data 240 and CRC error checking information 250.
• an acknowledgement packet is sent, including a preamble 260, a PLCP header 270 and an acknowledgement 280.
• the 802.11 -defined Medium Busy signal (Mbusy) is driven high during the time the forward IEEE packet is detected, and the signal WLMBsy is initially high when MBusy is high, but is driven low if the forward packet is "Not for me", i.e. not for this transceiver.
• Bluetooth communications are deferred if WLMBsy is high, and no Bluetooth signals can be transmitted whilst the IEEE 802.11 acknowledgement packet is being sent.
• the BTMBsy signal can be used to force the WLAN transmitter to defer (not backoff).
• the IEEE 802.1 1 WMAC will sample the BTMBsy signal just prior to the WLAN TX start, and defer if needed, sampling at slot time intervals (20 ⁇ s (for 802.11 b)/9 ⁇ s (for 802.11 a/g)J.
• a simple OR function of the IEEE 802.11 MBusy signal and the BTMBsy signal is not desirable. While the IEEE 802.11 MBusy signal is active and de-asserted a backoff timing interval counter is initiated and the IEEE 802.1 1 WMAC will not be able to transmit on the media until the expiry of this timer.
• the assertion of the BTMBsy signal implies that the BT media is busy but on the de-assertion of this signal, if the IEEE 802.11 WMAC has transmit data queued up and ready to send on the media, it should be free to do so.
• the BTMBsy signal is governed by the following equation:
• PreventSimTX "Prevent Simultaneous Transmit” is a software controllable signal that will be logically high when the system requires the prevention of simultaneous transmits on the IEEE 802.11 medium and the Bluetooth medium.
• TX BUSY is logically high when Bluetooth transmit is active for the system.
• RXBusyEnable is a software controllable signal that will be logically high when the Bluetooth Baseband is receiving to indicate to the IEEE 802.11 MAC that the Bluetooth receive window is open.
• Fig. 3. shows timing of an exemplary Bluetooth BTMBsy signal while operating in asynchronous mode, in accordance with the principles of the present invention.
• a first Bluetooth packet includes a header 310 and data 320, and a second packet including a header 330 and data 340.
• the solid lines represent the BTMBsy signal in the case where the Bluetooth packets are not addressed to the BT baseband equipment, whereas the dotted lines in the BTMBsy signal show that the BTMBsy signal stays high until the end of the BT packets in the case where the BT packets are addressed to the BT baseband equipment.
• Two different embodiments are shown, and these are designated as Option 1 and Option 2.
• the BTMBsy signal is driven active at 72 microseconds based upon the BT baseband equipment's knowledge that correlated data has been received. Then, upon conclusion of the header data, the BT baseband equipment can then either keep the signal active (if the received data is for it), or it can drive it inactive (low) if the received data has not been addressed to it. This embodiment has the shortcoming of not being able to reduce interference during the period of time when the BT baseband would be determining if any packets are on the medium during that slot.
• the BTMBsy signal is driven active at the start of a
• the BT receive slot regardless of whether or not correlated data has been received. This would be done to decrease the probability of interference during the time when the BT baseband equipment would be trying to determine if there are any packets on the medium during that slot. Then, the BTMBsy signal could be driven low at 72 microseconds if no packet is on the medium, or at the end of the header if there is a packet, but it is not for this device. If the packet comes in and is addressed for this device, then BTMBsy would be active until the end of the data.
• the mailbox may be considered to be one or more memory locations, and as such may be considered to be a "plurality of mailboxes" to convey that more than one memory location is used (at least one designated for each communication direction) to provide full duplex communications.
• BTSYNC The signal that may communicate BT time to the WMAC is referred to herein as BTSYNC.
• the BTSYNC signal will likely become active only when the system is presently in an active Bluetooth link. To that end, the BTSYNC signal will be driven low under the following conditions:
• the system is not participating in a Bluetooth link
• Fig. 4 shows exemplary synchronous signal timing of a
• Bluetooth BTSYNC signal in accordance with the principles of the present invention.
• the BTSYNC signal is driven high t4 after the beginning of each Transmit (TX) period and driven low t5 after the beginning of each Receive (RX) period.
• xDATAVALID signals are used to signal to each service that mailbox data has arrived and/or is presently valid. The type of data that has been written to the mailbox is not important to the operation of the xDATAVALID signals.
• BTDATAVALID The purpose of BTDATAVALID is to indicate the validity of the BT Mailbox data written by the Bluetooth Baseband, and hence when the IEEE 802.11 MAC should read the BT Mailbox.
• BTDATAVALID high means BT Mailbox data is valid, and may be read by the IEEE 802.11 MAC.
• BTDATAVALID low means the BT Mailbox data is not valid (is being updated), and should not be read by the IEEE 802.11.
• An IEEE 802.11 MAC Event will be assumed on a rising edge of the BTDATAVALID signal. Note that the BTDATAVALID signal will be driven low by the Bluetooth Baseband while writing the BT Mailbox.
• Fig. 5 shows characteristics of an exemplary BTDATAVALID signal, in accordance with the principles of the present invention.
• n-2, n-1 and n each including a transmit period (TX) and a receive period (RX) having durations of 625 microseconds.
• the BTDATAVALID signal is shown remaining high in frame n-1 for time t1 , then going low for time t3 and back to high for time t2, and the same in frame n.
• the IEEE 802.11 MAC may read the BT mailbox.
• BTDATAVALID is low during time t3
• the BT baseband equipment may write to the BT mailbox, and the BT mailbox information for the next successive frame is updated.
• the purpose of WLDATAVALID is to indicate the validity of the
• WL Mailbox data written by the IEEE 802.11 MAC and hence indicate when the Bluetooth Baseband should read the WL Mailbox.
• a HIGH condition of the WLDATAVALID signal in the exemplary embodiment indicates that WL Mailbox data is valid, and thus may be read by the Bluetooth Baseband system.
• a LOW condition of the WLDATAVALID signal indicates that the WL Mailbox data is not valid (i.e., is being updated), and should not be read by the Bluetooth Baseband system.
• the WLDATAVALID signal will be driven low by the IEEE 802.11 MAC when the WMAC is writing to the WL Mailbox.
• Fig. 6 shows characteristics of an exemplary BTDATAVALID signal indicating when IEEE 802.11 (WiFi) data is valid, in accordance with the principles of the present invention.
• the WMAC BTDATAVALID Read Protocol is as shown in the following table:
• This invention provides a means by which two co-located, disparate wireless systems can avoid interference with one another by including a direct communication link therebetween to generically exchange state information.
• exemplary state information includes, but is not limited to, e.g., exchanging scheduling information, mode of operation information, 802.11 channel usage information, and/or device state information.
• the 802.11 channel usage information may be used, e.g., to allow adaptive frequency hopping by a Bluetooth system around the 802.11 channels in use at the same time.
• the direct communication interface described herein allows each disparate wireless service to make intelligent decisions on common or close frequency band usage.
• the solutions described herein may be implemented in a straightforward manner, e.g., by dedicating a number of pins to support a hard-wired direct communication link, thereby permitting operable coexistence between BT and IEEE 802.11 transceivers.

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• Signal Processing (AREA)
• Quality & Reliability (AREA)
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• Small-Scale Networks (AREA)

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• 2003
  • 2003-06-25 EP EP03811184A patent/EP1568164A4/de not_active Withdrawn
  • 2003-06-25 WO PCT/US2003/019852 patent/WO2004045082A2/en not_active Ceased
  • 2003-06-25 JP JP2005506692A patent/JP2006521714A/ja active Pending
  • 2003-11-13 AU AU2003295486A patent/AU2003295486A1/en not_active Abandoned
  • 2003-11-13 WO PCT/US2003/036155 patent/WO2004045092A1/en not_active Ceased

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