WO2024084072A1

WO2024084072A1 - Arbitration circuit portions

Info

Publication number: WO2024084072A1
Application number: PCT/EP2023/079349
Authority: WO
Inventors: Sriram Kankipati; Murali Mohan THOKALA
Original assignee: Nordic Semiconductor Asa
Priority date: 2022-10-20
Filing date: 2023-10-20
Publication date: 2024-04-25

Abstract

An arbitration circuit portion for coordinating first and second radio circuit portions arranged to transmit and/or receive radio signals in a common frequency band is provided. The arbitration circuit portion comprises a memory storing a look-up table comprising a plurality of arbitration outcomes for a corresponding plurality of input states. The arbitration circuit portion is arranged to receive a communication request signal from the first radio circuit portion or the second radio circuit portion; determine an input state based at least partially on said communication request signal; use the look-up table to determine an arbitration outcome for said input state; and apply said arbitration outcome to the first and/or second radio circuit portions.

Description

Arbitration circuit portions

BACKGROUND OF THE INVENTION

The present invention relates to arbitration circuit portions for coordinating coexisting radio circuit portions.

Many different wireless radio communication protocols share the same or overlapping frequency bands. For instance, Bluetooth, Zigbee, Thread and some WLAN protocols use the 2.4 GHz ISM band, because in many countries it can be used at low powers without a specific licence. This can lead to communication issues when signals according to such protocols are transmitted simultaneously in close proximity (i.e. when multiple protocols coexist in the same area). When two or more radio communication protocols operate in close proximity and share the same frequency band, they are sometimes referred to as coexisting protocols.

Many modern devices can themselves support multiple wireless communication protocols that share the same frequency band - e.g. a modern mobile telephone may support a Bluetooth connection (e.g. with wireless headphones) at the same time as a wireless local area network (WLAN) connection (e.g. with a Wi-Fi router). Some devices are even arranged to use a common antenna for protocols sharing the same frequency band. To avoid interference issues, devices supporting multiple wireless communication protocols that share the same frequency band typically implement coexistence procedures. Conventional coexistence procedures include packet traffic arbitration (PTA), in which different radio modules send communication request signals (i.e. requests to send or receive a data packet in a particular time window) to an arbitration circuit, which issues a grant signal to only one radio module at a time.

Typically, a PTA circuit handles competing request signals using predetermined priority logic, e.g. always prioritising WLAN transmissions over Bluetooth transmissions. However, this approach may not be optimal for all conditions and may lead to situations in which one communication protocol dominates over the other. An improved approach may be desired. SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an arbitration circuit portion for coordinating first and second radio circuit portions arranged to transmit and/or receive radio signals in a common frequency band, said arbitration circuit portion comprising: a memory storing a look-up table comprising a plurality of arbitration outcomes for a corresponding plurality of input states; wherein said arbitration circuit portion is arranged to: receive a communication request signal from the first radio circuit portion or the second radio circuit portion; determine an input state based at least partially on said communication request signal; use the look-up table to determine an arbitration outcome for said input state; and apply said arbitration outcome to the first and/or second radio circuit portions.

Thus, it will be appreciated by those skilled in the art that the arbitration circuit portion may provide fast, simple and flexible arbitration between the first and second radio circuit portions, because a look-up table is used to determine an arbitration outcome (e.g. to determine whether to grant the communication request) rather than potentially complex decision-making logic circuitry.

Because arbitration outcomes are determined using the look-up table, arbitration rules can be changed simply by adjusting the relevant entries in the look-up table (or by replacing part of or the whole look-up table). Moreover, a user may be able to set up custom and potentially complex arbitration rules simply by adding the appropriate entries to the look-up table, without needing to design potentially- complicated logic hardware or software. Whilst the arbitration circuit portion must have a memory sufficient to store said look-up table, the applicant has recognised that this may be acceptable in many situations in return for increased speed and flexibility.

Moreover, the arbitration circuit portion may be adapted for use in a wide variety of radio devices and systems with coexistent radio circuit portions by simply employing a suitable look-up table and without needing to design and implement bespoke logic circuitry.

In a set of embodiments, the first radio circuit portion is arranged to transmit and/or receive radio signals according to a first wireless communication protocol. The first wireless communication protocol may be a wireless local area network (WLAN) protocol, e.g. according to one of the IEEE 802.11 standards, often referred to as Wi-Fi. In some embodiments, the second radio circuit portion is arranged to transmit and/or receive radio signals according to a second wireless communication protocol, different to said first wireless communication protocol. The second wireless communication protocol may be a wireless personal area network (WPAN) protocol e.g. according to one of the IEEE 802.15 standards. The second wireless communication protocol may be Bluetooth, Zigbee or Thread (e.g. Bluetooth Low Energy (BLE)). The first wireless communication protocol may support longer-range and/or higher data rate communications than the second wireless communication protocol.

Conversely, the second wireless communication protocol may be a wireless local area network (WLAN) protocol, and/or the first wireless communication protocol may be a wireless personal area network (WPAN) protocol.

The common frequency band may be an industrial, scientific and medical (ISM) radio band. For instance, the common frequency band may include frequencies between 2.4 GHz - 2.5 GHz.

The first and/or second radio circuit portion may comprise a radio transceiver circuit portion, i.e. arranged to transmit and receive radio signals. In some embodiments one or both of the first and/or second radio circuit portions may be arranged to only to transmit or only to receive. The communication request signals the arbitration circuit portion is arranged to receive may be transmit request signals or receive request signals.

The input state may simply correspond to the communication request signal, e.g., comprising an index of the look-up table corresponding to the communication request signal. For instance, the look-up table may contain a range of arbitration outcomes for different types and sources of communication request signal.

It may be advantageous to take one or more other pieces of information into account when determining the arbitration outcome. In a set of embodiments, the input state is determined taking into account a current activity of the first radio circuit portion and/or the second radio circuit portion. For instance, the input state may include information on whether the first radio circuit and/or the second radio circuit potion is currently transmitting, receiving or neither (i.e. is idle). The arbitration circuit portion may be arranged to maintain a record of the current activity of the first radio circuit portion and/or the second radio circuit portion. This record may, for instance, be updated each time the arbitration circuit portion applies a new arbitration outcome (e.g. the record may be updated to reflect an activity of the first radio circuit portion or the second radio circuit portion (e.g. a transmission) triggered by the arbitration outcome).

In some embodiments, the arbitration circuit portion may be arranged to receive communication request signals from only one of the first and second radio circuit portions. In other words, one of the first and second radio circuit portions may not itself be able to request permission to use the common frequency band. For instance, one of the first and second radio circuit portions may simply be unilaterally allocated use of the common frequency band at suitable times. However, preferably the arbitration circuit portion is arranged to receive communication request signals from the first radio circuit portion and the second radio circuit portion. The input state may be determined based at least partially on communication request signals from the first and second radio circuit portions (although, of course, requests from the first and second circuit portions may often not coincide). It will be appreciated that when the arbitration circuit portion determines an input state based on request signals from both the first and second radio circuit portion, the arbitration circuit portion is effectively acting directly as an arbiter between the first and second radio circuit portion to decide if the requests is granted (e.g. one, both or neither).

In some sets of embodiments, the arbitration circuit portion is arranged to receive supplementary information from at least one of the first and second radio circuit portions (e.g. in addition to or instead of a communication request signal). The arbitration circuit portion may be arranged to determine the input state taking into account said supplementary information. The supplementary information may comprise information related to a communication request from said first or second radio circuit portion. For instance, the supplementary information may indicate a communication type of the communication request (e.g. a transmission or a reception), and/or a priority of the communication request (e.g. whether the communication requested is of high priority or low priority). The supplementary information may, additionally or alternatively, comprise information that is not directly associated with a communication request, such as information indicating a current activity of the first or second radio circuit portion.

In a set of embodiments, the arbitration circuit portion is arranged to receive and decode a single signal in which several pieces of supplementary information are encoded (e.g. by time-multiplexing). For instance, a communication type and a priority of a communication request may be time-multiplexed in the same signal (e.g. with a first portion of the signal indicating a priority and a second portion of the signal indicating a type, or vice-versa).

The arbitration outcome may comprise a decision to grant the communication request, i.e. to permit the first or second radio circuit portion to perform the requested communication. Conversely, the arbitration outcome may comprise a decision not to grant the communication request (i.e. to refuse the request). The arbitration circuit portion may be arranged to apply the arbitration outcome by outputting a grant signal to the radio circuit portion from which the communication request was received (if the outcome is a decision to grant the request), or refraining from outputting a grant signal to the radio circuit portion from which the communication request was received (if the outcome is a decision not to grant the request). Conversely, applying the arbitration outcome may comprise the arbitration circuit portion outputting a refusal signal to the radio circuit portion from which the communication request was received, or refraining from outputting a refusal signal.

The arbitration outcome and its application may not necessarily relate only to the radio circuit portion from which the communication request was received. For instance, in a set of embodiments, the arbitration outcome comprises a decision to interrupt or abort an activity of the first or second radio circuit portion to facilitate communication of the radio circuit portion from which the communication request was received. Applying this may comprise the arbitration circuit portion outputting an abort signal to the first or second radio circuit portion. In a set of embodiments, additionally or alternatively, the arbitration outcome comprises a decision to inform the first or second radio circuit portion that the other radio circuit portion is currently communicating (i.e. is busy). Accordingly, the arbitration circuit portion may be arranged to output a busy signal to the first or second radio circuit portion to indicate that the other radio circuit portion is currently communicating, e.g. because a request from the other radio circuit portion has been granted.

The arbitration outcome may comprise a plurality of decisions, e.g. relating to one or both radio circuit portions. Applying the arbitration outcome may comprise outputting signals to both of the first and second radio circuit portions as explained above (i.e. grant, refusal, abort and/or busy signals). The arbitration outcome may comprise a decision to grant requests from both radio circuit portions, e.g. to allow both radio circuit portions to attempt to receive a communication at the same time. In some circumstances, it may be permissible to allow one of the radio circuit portions to transmit whilst the other is attempting to receive (e.g. when a failed reception attempt is acceptable, even if not desirable).

The arbitration outcome may not only relate to the first and second radio circuit portions. For instance, the arbitration outcome may comprise a decision to connect a shared antenna to one of the first and second radio circuit portions (e.g. because its communication request has been granted). The arbitration circuit portion may be arranged to output an antenna switching signal to control the connection of a shared antenna to the first and/or second radio circuit portion.

One or more actions for applying the arbitration outcome may be indicated directly by the arbitration outcome (e.g. indicated directly by one or more entries in the look-up table corresponding to the input state). This may allow the arbitration circuit portion to apply the arbitration outcome using minimal processing resources. For instance, the look-up table may comprise one or more 1- or 2- bit entries that indicate immediately an action for applying an arbitration action (e.g. asserting or de-asserting an output signal). As explained above, the input state and/or arbitration outcome may comprise multiple input and output variables. The look-up table may comprise a multidimensional array with separate entries for each combination of input and output variables. However, to simplify operation, in a set of embodiments the arbitration circuit portion is arranged to pack the determined input state into a single word corresponding to an entry in the look-up table (i.e. a word encoding the information defining the input state). Correspondingly, the arbitration outcome may comprise a single word stored in the look-up table, which can be unpacked to determine the actions needed to apply the outcome. The output word may also encode information on what the subsequent activity of the first and/or second radio circuit portions will be as a result of the arbitration outcome, e.g. to use to update a record of the current activity of the first radio circuit portion and/or the second radio circuit portion. In a set of embodiments the look-up table consists of a Nx2 array, with N input state words and N corresponding output state words. In some embodiments, the look-up table may even be a one dimension array consisting only of output state words, wherein the arbitration circuit portion is arranged to determine an index of said array corresponding to the input state.

In a set of embodiments, the arbitration circuit portion may comprise coexistence hardware arranged to determine and apply the arbitration outcome. The coexistence hardware may comprise a packet traffic arbiter (PTA) arranged to apply arbitration rules defined by the look-up table. As explained above, using a look-up table means that the PTA requires little processing power, and the rules applied by the PTA can be easily modified. The coexistence hardware may be arranged to receive the communication request signal. The coexistence hardware may be arranged to generate one or more signals to apply the arbitration outcome (e.g. grant, refusal, busy signals). The coexistence hardware may comprise one or more interfaces for sending and/or receiving signals from the first and/or second radio circuit portions.

The arbitration circuit portion may comprise a controller arranged to manage operation of the coexistence hardware (i.e. to act as a coexistence manager).

For instance, the coexistence hardware may comprise an interface arranged to decode a signal from the first or second radio circuit portion in which several pieces of supplementary information are encoded (e.g. with time-multiplexing), and to send said decoded signal to the PTA.

The arbitration circuit portion (e.g. the coexistence hardware, a PTA or an interface) may be arranged to be connected to the first radio circuit portion or the second radio circuit portion by a 1-wire connection (e.g. a single conductor). The 1-wire connection may provide a single communication channel for sending a grant signal to the first or second radio circuit portion. In some embodiments, the arbitration circuit portion is arranged to be connected to the first radio circuit portion or the second radio circuit portion by a 2-wire connection, e.g. facilitating the reception of request signals and the issuing of grant signals. In some embodiments, the arbitration circuit portion is arranged to be connected to the first radio circuit portion or the second radio circuit portion by a 3- or 4-wire connection, e.g. facilitating the reception of request signals, the issuing of grant signals and the reception of supplementary information.

The arbitration circuit portion may be provided as a separate device to the first and second radio circuit portions. In other words, the arbitration circuit portion may be a standalone circuit arranged to facilitate coexistence between two (or more) separate radio circuit portions. However, in a set of embodiments, the arbitration circuit portion is provided with the first radio circuit portion. For instance, the arbitration circuit portion may comprise part of a radio processing unit that also comprises the first radio circuit portion. Accordingly, the invention extends to a radio processing unit comprising: a first radio circuit portion arranged to transmit and/or receive radio signals in a common frequency band; and the arbitration circuit portion as disclosed herein, arranged to coordinate the first radio circuit portion and a second radio circuit portion arranged to transmit and/or receive radio signals in the common frequency band.

In embodiments where the arbitration circuit portion is provided with the first radio circuit portion, inputs from the first radio circuit portion to the arbitration circuit portion and outputs from the arbitration circuit portion to the first radio circuit portion (e.g. request and grant signals) may comprise internal logic connections. As explained above, the arbitration rules applied by the arbitration circuit portion can advantageously be changed simply by adjusting relevant entries in the look-up table (or by replacing part of or the whole look-up table). In a set of embodiments, the arbitration circuit portion is arranged to change one or more entries in the lookup table in response to an adjustment signal. For instance, an adjustment signal may be received from a host device when the host device detects a change or an imminent change in a coexistence scenario.

The adjustment signal may comprise an instruction to change one or more entries in the look-up table (e.g. to change one or more specific aspects of an arbitration outcome for a given input state, or to change whole sections of the look-up table). The adjustment signal may simply comprise new entries themselves, or simply instructions on how the existing entries should be changed. In a set of embodiments, the adjustment signal comprises an instruction to change the entire look-up table. The adjustment signal may comprise a new look-up table to replace the existing look-up table, or instructions on how the look-up table should be changed. In some embodiments, the memory of the arbitration circuit portion is arranged to store a plurality of look-up tables, and the adjustment signal may indicate which look-up table to use for arbitration.

In a set of embodiments, the adjustment signal comprises a request to change the look-up table, e.g. a request to prioritise one of the first or second radio circuit portions in arbitration decisions. For instance, the adjustment signal may comprise a request from one of the first or second radio circuit portions to start a priority time window in which communication requests from that device are prioritised.

The coexistence hardware may be arranged to process and act on the adjustment signal itself. However, in a set of embodiments the arbitration circuit portion comprises a controller (e.g. a coexistence manager) arranged to receive the adjustment signal and to control the coexistence hardware appropriately.

Adjustment signals may be received from a host device, e.g. a processor of a host device. The host device may also be arranged to control the first and/or second radio circuit portions (e.g. to send data for transmission to the first and/or second radio circuit portion and/or to receive data received by the first and/or second radio circuit portion). Additionally or alternatively, adjustment signals may be received from other sources who may usefully update the look-up table. For instance, adjustment signals may be received from the first and/or second radio circuit portions themselves. For instance, an adjustment signal from one of the first and second radio circuit portions may comprise a request for a priority time window in which communication requests from that device are prioritised.

According to a second aspect there is provided a method of coordinating first and second radio circuit portions arranged to transmit and/or receive radio signals in a common frequency band, said method comprising: receiving a communication request signal from the first radio circuit portion or the second radio circuit portion; determining an input state based at least partially on said communication request signal; using a look-up table comprising a plurality of arbitration outcomes for a corresponding plurality of input states to determine an arbitration outcome for said input state; and applying said arbitration outcome to the first and/or second radio circuit portions.

The invention extends to computer software that, when executed by an arbitration circuit portion, causes said arbitration circuit portion to perform the method disclosed herein. The arbitration circuit portion may comprise a memory storing said software. The arbitration circuit portion may comprise a processor arranged to execute said software.

According to a third aspect there is provided a radio system comprising: a host device; a first radio circuit portion controlled by the host device and arranged to transmit and/or receive radio signals in a common frequency band; a second radio circuit portion controlled by the host device and arranged to transmit and/or receive radio signals in the common frequency band; and the arbitration circuit portion as disclosed herein, arranged to coordinate said first and second radio circuit portions. As mentioned above, the host device may be arranged to send an adjustment signal to the arbitration circuit portion, e.g. comprising an instruction or request to change one or more entries in the look-up table. The host device may comprise a processor arranged to generate the adjustment signal, e.g. according to coexistence driver software. Additionally or alternatively, the first and/or second radio circuit portion may be arranged to send an adjustment signal directly to the arbitration circuit portion, e.g. comprising an instruction or request to change one or more entries in the look-up table. For instance, the first and/or second radio circuit portion may comprise a medium access control processor (e.g. a WLAN media access control (MAC) processor or a BLE link controller or link manager) arranged to send an adjustment signal to the arbitration circuit portion, e.g. in response to current or planned communication activity of the relevant radio circuit portion.

As explained above, the use of a look-up table by the arbitration circuit portion means that the coexistence decisions it makes can be easily and quickly adjusted when necessary. In a set of embodiments, the host device may be arranged to send an adjustment signal to the arbitration circuit portion in response to detecting a change of coexistence scenario (i.e. a change in how the first and/or second radio circuit portion uses the common frequency band). In a set of embodiments, the host device may be arranged to send an adjustment signal to the arbitration circuit portion in response to detecting state information regarding the first and/or second radio circuit portion.

For instance, the host device may be arranged to receive state information from the first and/or second radio circuit portions, and to send an adjustment signal to the arbitration circuit portion that instructs the arbitration circuit portion to use a look-up table suitable for said detected state information (e.g. in which one of the first or second radio circuit portions is favoured in arbitration decisions). Correspondingly, the first and/or second radio circuit portion may be arranged to send state information to the host device (e.g. from a MAC level process on the first and/or second radio circuit portion).

Changing the arbitration applied by the arbitration circuit portion in response to state information is not normally possible with conventional coexistence protocols, because conventional arbiters are typically only configured to respond directly to packet-level request signals. Moreover, conventional arbiters do not use look-up tables and therefore cannot be easily and quickly updated anyway. Adapting coexistence arbitration according to real-time state information may improve the performance of the radio system, e.g. better utilising radio resources and/or avoiding one radio circuit portion unfairly dominating use of the common frequency band.

In a set of embodiments, the state information may comprise a mode or setting in which the first and/or second radio circuit portion is operating (or is about to operate), such as an idle mode, an advertisement mode, a scan mode or a connection mode. Additionally or alternatively, the state information may comprise an indication that the first and/or second radio circuit portion is moving to a different frequency band to the common frequency band, e.g. a WLAN radio moving from the 2.4 GHz band to the 5 GHz band. In such a scenario, the host device may send an adjustment signal to the arbitration circuit portion which indicates that a liberal look-up table should be used for arbitration. This look-up table may, for instance, allow almost all or all communication requests from the first and second radio circuit portions (because they are no longer sharing the common frequency band).

Additionally or alternatively, the state information may comprise power state information, e.g. information on whether the first and/or second radio circuit portion is in an active mode or a sleep mode. For instance, different look-up table entries giving different arbitration decisions may be appropriate when one device is in a sleep mode and the other is active.

The radio system may comprise a common antenna arranged to be used for communication by the first and second radio circuit portions. Alternatively, the radio system may comprise separate first and second antennas for the respective first and second radio circuit portions. As mentioned above, the arbitration circuit portion can easily be adapted for use in implementations with shared or separate antennas simply by loading an appropriate look-up table.

The arbitration circuit portion has been described herein in the context of coordinating first and second radio circuit portions arranged to transmit and/or receive radio signals in a common frequency band (i.e. first and second coexisting radio circuit portions). However, the arbitration circuit portion is not limited to coordinating only two radio circuit portions. In a set of embodiments, the arbitration circuit portion also coordinates a third radio circuit portion arranged to transmit and/or receive signals in the common frequency band. For instance, the arbitration circuit portion may be arranged to receive a communication request signal from a third radio circuit portion and/or to apply the arbitration outcome to a third radio circuit portion.

Features of any aspect or embodiment described herein may, wherever appropriate, be applied to any other aspect or embodiment described herein. Where reference is made to different embodiments, it should be understood that these are not necessarily distinct but may overlap. It will be appreciated that all of the preferred features of the arbitration circuit portion according to the first aspect described above may also apply to the other aspects of the invention where appropriate, and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more non-limiting examples will now be described, by way of example only, and with reference to the accompanying figures in which:

Figure 1 is a schematic view of a radio communication system according to an embodiment of the invention;

Figure 2 is a schematic view of coexistence hardware in the radio communication system of Figure 1 ;

Figure 3 shows an extract from a look-up table used by the coexistence hardware; and

Figure 4 is a timing diagram illustrating operation of the radio communication system.

DETAILED DESCRIPTION

A radio communication system 100 is shown in Figure 1. The system 100 comprises a host device 102, a WLAN radio device 104, an RF switch 105 and a shared antenna 107. The host device 102 comprises a host processor 103, a memory 106 and a Bluetooth Low Energy (BLE) radio module 108. The WLAN radio device 104 comprises a WLAN radio module 110 and an arbitration circuit portion 112, comprising a controller 114 and coexistence hardware 116. The radio communication system 100 may comprise other radio transmission and reception circuitry not shown.

The memory 106 stores software that is run by the host processor 103 to provide a Bluetooth driver 118 that uses the BLE radio module 108 to send and receive BLE radio packets, and a WLAN driver 120 that uses the WLAN radio module 110 to send and receive WLAN radio packets. The processor 103 also provides a coexistence driver 122 which communicates with the arbitration circuit portion 112.

The BLE radio module 108 sends and receives radio packets using the 2.4 GHz frequency band (i.e. a frequency range near 2.4 GHz). The WLAN radio module 110 can send and receive radio packets using the 2.4 GHz frequency band and a 5 GHz frequency band. The BLE radio module 108 and the WLAN radio module 110 share the same antenna 107. Access to the antenna 107 by the BLE radio module 108 and the WLAN radio module 110 is controlled by the RF switch 105, which is, in turn, controlled by the coexistence hardware 116.

Figure 2 shows the coexistence hardware 116 in more detail. The coexistence hardware 116 comprises a packet traffic arbiter (PTA) 124, an interface 126 for communicating with the BLE radio module 108 and an antenna selection map (ASM) 109. The arbitration circuit portion 112 is part of the WLAN radio device 104, so no interface is required for the WLAN radio module 110. The PTA 124 comprises a memory 128 in which an arbitration look-up table is stored. An extract from an example arbitration look-up table 300 is shown in Figure 3. The look-up table stores a series of arbitration outcomes corresponding to a series of input states, the input states including the current activity of the radio modules 108, 110 and the input signals discussed below. The arbitration outcomes indicate a series of output signals for the coexistence hardware 116 to issue.

The PTA 124 has a plurality of inputs for receiving different input signals from the BLE radio module 108 and the WLAN radio module 110. The PTA 124 can receive a WLAN request signal WR, a WLAN communication type signal WTR, a WLAN priority signal WRP, a BLE request signal BR, a BLE communication type signal BTR and a BLE priority signal BRP. The BLE communication type signal BTR and a BLE priority signal BRP are generated by the interface 126 in response to a BLE status signal BRS from the BLE radio module 108, explained in more detail below. In this embodiment, the interface 126 has a 3-wire connection to the BLE radio module 108, and provides a 4-wire connection to the PTA 124.

The PTA 124 also has a plurality of outputs for outputting various signals to the BLE radio module 108, the WLAN radio module 110 and to the RF switch 105 (via the ASM 109). The PTA 124 can issue a WLAN transmission abort signal l/VTA, a BLE busy signal BCB, a BLE grant signal BG and an RF switch control signal SC. The ASM 109 maps the RF switch control signal SC to physical control of the RF switch 105.

In use, the BLE and WLAN radio modules 108, 110 are used to send and receive radio packets under the control of the host device 102. However, because the BLE and WLAN radio modules 108, 110 can both operate in the 2.4 GHz frequency band, the radio communication system 100 uses the arbitration circuit portion 112 to coordinate the communications of the BLE and WLAN radio modules 108, 110 to mitigate interference. Operation of the radio communication system 100 will now be described with additional reference to the timing diagram 400 shown in Figure 4.

At a first time ti, the WLAN radio module 110 is operating in the 2.4 GHz frequency band, i.e. sharing the frequency band with the BLE radio module 108.

At the first time ti, the BLE and WLAN radio modules 108, 110 are IDLE (i.e. not transmitting or receiving). By default, the shared antenna 107 is connected to the WLAN radio module 110. So, at time ti, SC is shown as WLAN. The WLAN radio module 110 wishes to transmit a high-priority WLAN data packet. It asserts the WLAN request signal WR and sets the WLAN communication type signal WTR and WLAN priority signal WRP to be high, to indicate that the requested communication is a high-priority transmission. At ti , the other input signals BR, BRS are all not asserted (because the BLE radio module 108 is not transmitting or receiving).

Based on the input signals, the PTA 124 determines the current input state and finds the corresponding entry 302 in the look up table 300. The PTA 124 then reads the corresponding arbitration outcome for that entry 302. As indicated in Figure 3, the outcome is to set the WLAN transmission abort signal l/VTA, the BLE busy signal BOB and the BLE grant signal BG to be low, and the set the RF switch control signal SC to “WLAN_TX”, i.e. granting the WLAN request. The entry 302 also indicates the next state of the BLE and WLAN radio modules 108, 110, i.e. that the BLE radio module 108 will still be IDLE, and the WLAN radio module 110 will be transmitting. This state is illustrated between ti and t2 in Figure 4.

At t2, the BLE radio module 108 wishes to transmit a low-priority BLE data packet. It asserts the BLE request signal BR and uses the BLE status signal BRS to indicate that the BLE communication type is TX and the priority is low. The BLE status signal BRS is low at t2 and then set high a short while later at time t₃. The BLE status signal BRS encodes the type and priority of the request, with the initial state of the BLE status signal BRS (between t2 and t₃) indicating the priority level of the request (low), and a later state of the BLE (e.g. after ta) indicating the type of the request (transmission). The interface 126 decodes the BLE status signal BRS and produces the corresponding BLE communication type signal BTR (high, to indicate a transmission) and BLE priority signal BRP (low).

At t4, with both type and priority information available, the PTA 124 re-assesses the current state and input signal, and finds the corresponding entry 304 in the look-up table 300. The column titled X<Y in the look-up table 300 indicates whether the priority of a new request (X) is less than the priority of an ongoing request (Y). The PTA 124 then reads the corresponding arbitration outcome for that entry 304. As indicated in Figure 3, the outcome is to leave all of the outputs as they currently are, i.e. to prioritise the ongoing WLAN transmission. The request from the BLE radio module 108 is thus not granted. The BLE radio module 108 sees that the status of the BLE grant signal BG is low and de-asserts the request signal BR and stops its planned transmission. There is no change in WLAN state and WLAN continues its transmission.

At a later time ts, the WLAN radio module 110 has finished transmitting and lowers the WLAN request signal WR, WLAN communication type signal WTR and WLAN priority signal WRP. The PTA 124 re-assesses the current input state, and finds the corresponding entry 306 in the look-up table 300. The PTA 124 then reads and applies the corresponding arbitration outcome for that entry 306. The BLE radio module 108 and the WLAN radio module are both IDLE.

At te, the BLE radio module 108 again wishes to transmit a low-priority BLE data packet and asserts the request signal BR. The BLE status signal BRS is set low at te and high a short time later at t? to indicate that the BLE communication type is TX and the priority is low. At te, with both type and priority signals information available, the PTA 124 re-assesses the current state and input signal, and finds the corresponding entry 308 in the look-up table 300. As indicated in Figure 3, the outcome is to grant the request from the BLE radio module 108. The BLE grant signal BG is set high and the RF switch control signal SC to “BLE_TX”, to cause the antenna 107 to be connected to the BLE radio module 108. The BLE radio module 108 transmits the packet.

At tg, the packet has been transmitted, and the BLE radio module 108 lowers the request signal BR. The PTA 124 re-assesses the input state and takes the action indicated by entry 310 in the look up table 300. The BLE radio module 108 and the WLAN radio module are both once again IDLE.

At a later time (not illustrated in Figure 4), the BLE radio module 108 moves into an advertising state, in which it transmits advertising packets and listens for responses. This change of state is communicated to the host device 102. In response, the coexistence driver 122 sends an adjustment signal to the controller 114 of the arbitration circuit portion 112 to change the arbitration look-up table used by the PTA 124.

The new arbitration look-up table prioritises all BLE packets over WLAN packets to maximise the number of advertising packets that are sent. Once the advertising period has ended, the BLE radio module 108 moves out of the advertising state, and the coexistence driver 122 sends another adjustment signal to the controller 114 of the arbitration circuit portion 112 to change the arbitration look-up table used by the PTA 124 back to the original look-up table (shown in Figure 3).

Other changes of state of the BLE and WLAN radio modules 108, 110 may also trigger adjustments to the look-up table. An adjustment signal may also be sent to the arbitration circuit portion 112 directly from the BLE or WLAN radio modules 108, 110. For instance, the WLAN radio module 110, when entering the connection state, may send an adjustment signal directly to the controller 114 of the arbitration circuit portion 112 without passing through the host device 102. The adjustment signal may comprise a priority request, indicating that the WLAN radio module 110 requests priority access to the 2.4 GHz band. In response to such an adjustment signal the controller 114 may adjust entries in the look-up table to prioritise the WLAN radio module 110, or may even swap out the entire currently-active look-up table for a different look-up table (e.g. stored in the memory 128 or elsewhere in the arbitration circuit portion 112), in which the arbitration outcomes prioritise the WLAN radio module 110.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

1. An arbitration circuit portion for coordinating first and second radio circuit portions arranged to transmit and/or receive radio signals in a common frequency band, said arbitration circuit portion comprising: a memory storing a look-up table comprising a plurality of arbitration outcomes for a corresponding plurality of input states; wherein said arbitration circuit portion is arranged to: receive a communication request signal from the first radio circuit portion or the second radio circuit portion; determine an input state based at least partially on said communication request signal; use the look-up table to determine an arbitration outcome for said input state; and apply said arbitration outcome to the first and/or second radio circuit portions.

2. The arbitration circuit portion of claim 1, wherein the input state is determined taking into account a current activity of the first radio circuit portion and/or the second radio circuit portion.

3. The arbitration circuit portion of claim 1 or 2, arranged to maintain a record of the current activity of the first radio circuit portion and/or the second radio circuit portion.

4. The arbitration circuit portion of any preceding claim, arranged to receive communication request signals from the first radio circuit portion and the second radio circuit portion, and to determine the input state based at least partially on communication request signals from the first and second radio circuit portions.

5. The arbitration circuit portion of any preceding claim, arranged to receive supplementary information from at least one of the first and second radio circuit portions and to determine the input state taking into account said supplementary information.

6. The arbitration circuit portion of any preceding claim, wherein applying the arbitration outcome comprises outputting signals to both of the first and second radio circuit portions.

7. The arbitration circuit portion of any preceding claim, wherein one or more actions for applying the arbitration outcome are indicated directly by one or more entries in the look-up table corresponding to the input state.

8. The arbitration circuit portion of any preceding claim, arranged to change one or more entries in the look-up table in response to an adjustment signal.

9. The arbitration circuit portion of any preceding claim, comprising coexistence hardware arranged to determine and apply the arbitration outcome and a controller arranged to manage operation of the coexistence hardware.

10. The arbitration circuit portion of claim 9, wherein the coexistence hardware comprises a packet traffic arbiter (PTA).

11. The arbitration circuit portion of any preceding claim, arranged to pack the determined input state into a single word corresponding to an entry in the look-up table.

12. The arbitration circuit portion of any preceding claim, wherein the first radio circuit portion is arranged to transmit and/or receive radio signals according to a wireless local area network protocol, and the second radio circuit portion is arranged to transmit and/or receive radio signals according to a wireless personal area network protocol.

13. A radio processing unit comprising: a first radio circuit portion arranged to transmit and/or receive radio signals in a common frequency band; and the arbitration circuit portion of any preceding claim herein, arranged to coordinate the first radio circuit portion and a second radio circuit portion arranged to transmit and/or receive radio signals in the common frequency band.

14. A method of coordinating first and second radio circuit portions arranged to transmit and/or receive radio signals in a common frequency band, said method comprising: receiving a communication request signal from the first radio circuit portion or the second radio circuit portion; determining an input state based at least partially on said communication request signal; using a look-up table comprising a plurality of arbitration outcomes for a corresponding plurality of input states to determine an arbitration outcome for said input state; and applying said arbitration outcome to the first and/or second radio circuit portions.

15. Computer software that, when executed by an arbitration circuit portion, causes said arbitration circuit portion to perform the method of claim 14.

16. A radio system comprising: a host device; a first radio circuit portion controlled by the host device and arranged to transmit and/or receive radio signals in a common frequency band; a second radio circuit portion controlled by the host device and arranged to transmit and/or receive radio signals in the common frequency band; and the arbitration circuit portion of any of claims 1-12, arranged to coordinate said first and second radio circuit portions.

17. The radio system of claim 16, wherein the host device is arranged to send an adjustment signal to the arbitration circuit portion comprising an instruction or request to change one or more entries in the look-up table.

18. The radio system of claim 17, wherein the host device is arranged to send the adjustment signal to the arbitration circuit portion in response to detecting state information regarding the first and/or second radio circuit portion.

19. The radio system of claim 18, wherein the state information comprises a mode or setting in which the first and/or second radio circuit portion is operating, an indication that the first and/or second radio circuit portion is moving to a different frequency band to the common frequency band and/or power state information.

20. The radio system of any of claims 16-19, comprising a common antenna arranged to be used for communication by the first and second radio circuit portions.