Data transfer using the bluetooth low energy standard

RELATED APPLICATIONS

0001This application is a non-provisional application from, and hereby claims priority under 35 U.S.C. §120 to, U.S. provisional patent application No. 61/551,372, titled “Data Transfer using the Bluetooth Low Energy Standard,” by inventors Joakim Linde and Brian J. Tucker, filed on 25 Oct. 2011, which is incorporated by reference (Atty Docket No. APL-P12879USP1).

BACKGROUND

00021. Field

0003The described embodiments relate to electronic devices with network connections. More specifically, the described embodiments relate to electronic devices that transfer data using the Bluetooth Low Energy standard.

00042. Related Art

0005Many modern electronic devices include a networking subsystem that is used to communicate with other electronic devices. For example, these electronic devices can include networking subsystem with a cellular network interface (UMTS, LTE, etc.), a Bluetooth interface, and/or a wireless network interface (e.g., a wireless network such as described in the Institute of Electrical and Electronics Engineers (IEEE) standards 802.11).

0006These electronic devices sometimes wirelessly communicate with electronic devices that have very restrictive power-consumption requirements. For example, low-power electronic devices such athletic heart rate monitors and other such devices can require that power consumption by the device be kept at very low levels to preserve battery life in the device. Because many of the currently-available standards for wirelessly communicating between devices consume too much power, the standards often cannot be used when communicating with these low-power devices. For example, one commonly-used standard used to wirelessly communicate between electronic devices is the Bluetooth Classic standard (“BTC”), which is described in the Core v. 4.0 Specification for the Bluetooth System from the Bluetooth Special Interest Group (SIG) of Kirkland, Wash.). However, BTC consumes too much power to be used for communicating with many devices with restrictive power-consumption requirements. The Bluetooth Specification also describes the Bluetooth Low Energy standard (“BTLE”) that enables data transfer using significantly less power than BTC. The BTLE standard can be used to communicate with some of these lower-power devices without consuming too much power.

0007In describing BTLE, the Bluetooth Specification describes an event-based communication scheme for managing communications between devices. When using BTLE, the devices first agree, while establishing a BTLE network connection, on a schedule of events that occur at corresponding times. Then, while subsequently using the BTLE network connection, during each event, the devices are configured to send data to and receive data from the other device (if data is available to be sent/received). <figref idref="DRAWINGS">FIG. 1</figref> presents a timeline diagram illustrating an example of the BTLE event-based communication scheme. More specifically, <figref idref="DRAWINGS">FIG. 1</figref> presents two timelines, one for a first device, and the other for a second device. As can be seen in <figref idref="DRAWINGS">FIG. 1</figref>, the first device has a sending window that occurs first during a given event (e.g., E<b>0</b> or E<b>1</b>), and the second device has a receiving window that occurs when the first device is in its sending window. In addition, the second device has a sending window that occurs during the event, and the first device has a corresponding receiving window. To ensure that the communications from one device can be received by the other device, the devices are configured to communicate at a given frequency during a corresponding event.

0008In BTLE systems, when a device successfully receives data, the device sends an acknowledge message to the other device to acknowledge the successful receipt of the data. For example, using the timelines in <figref idref="DRAWINGS">FIG. 1</figref>, during event E<b>0</b>, the first device could send data in its sending window, and the second device could receive the data. The second device then sends an acknowledge message in its own sending window. If the first device does not receive an acknowledge message (because, e.g., the data arrived at the second device corrupted in some way), the first device awaits its next sending window during the next event and resends the data at the same frequency. The first device continues to resend the data at each event, at the same frequency, until receiving an acknowledge message from the second device.

0009Because the devices can be subject to interference (e.g., between a device and other devices in the environment in which the device is located), data sent by a first device to a second device can arrive in a corrupted state. However, resending the data at the same frequency at the next event can again be unsuccessful because the devices may be subject to the same source of interference. This may result in a device repeatedly attempting to resend data and continuing to encounter the same interference. Because some data is “timely,” and hence generally should arrive at a given time and in a given sequence with respect to prior and subsequent data, the repeated resending of data can result in suboptimal performance for the devices, which can lead to an undesirable user experience.

SUMMARY

0010The described embodiment include system for communicating between electronic devices. During operation in some embodiments, a transmitting electronic device transmits a first data channel protocol data unit (PDU) to a receiving electronic device using a Bluetooth Low Energy (BTLE) interface in a sending window for the transmitting electronic device during a regular event, wherein the first data channel PDU comprises a payload with data D, and wherein transmitting the first data channel PDU during the regular event comprises using a first frequency to transmit the first data channel PDU using the BTLE interface. The transmitting electronic device then transmits a second data channel PDU to the receiving electronic device using the BTLE interface in a sending window for the transmitting electronic device during a corresponding retransmission event, wherein the second data channel PDU comprises a payload with the same data D, and wherein transmitting the second data channel PDU during the retransmission event comprises using a second frequency to transmit the second data channel PDU using the BTLE interface.

0011In some embodiments, when transmitting the second data channel PDU during the retransmission event, the transmitting electronic device is configured to automatically transmit the second data channel PDU without receiving a request from the receiving electronic device to transmit the second data channel PDU.

0012In some embodiments, the transmitting electronic device is configured to receive a message from the receiving electronic device that indicates that the PDU was received successfully in a receiving window for the transmitting electronic device during at least one of the regular event or the retransmission event.

0013In some embodiments, the data D comprises audio data.

0014In some embodiments, the first frequency is a different frequency than the second frequency.

0015In some embodiments, the receiving electronic device is an assistive-listening device.

0016In some embodiments, prior to transmitting PDUs during the regular event and the retransmission event, the transmitting electronic device is configured to communicate with the receiving electronic device to configure a schedule of times at which the regular event and the retransmission events occur.

0017In addition, during operation in some embodiments, a receiving electronic device receives a first data channel PDU from a transmitting electronic device using a BTLE interface in a receiving window for the receiving electronic device during a regular event, wherein the first data channel PDU comprises a payload with data D, and wherein receiving the first data channel PDU during the regular event comprises using a first frequency to receive the first data channel PDU using the BTLE interface. The receiving electronic device is configured to determine if the first data channel PDU was received with the data D in a correct condition. When the first data channel PDU was not received with the data D in the correct condition, the receiving electronic device is configured to receive a second data channel PDU from the transmitting electronic device using the BTLE interface in a receiving window for the receiving electronic device during a corresponding retransmission event, wherein the second data channel PDU comprises a payload with the same data D, and wherein receiving the second data channel PDU during the retransmission event comprises using a second frequency to receive the second data channel PDU using the BTLE interface.

0018In some embodiments, the first data channel PDU was received with the data D in the correct condition, the receiving electronic device is configured to configure one or more portions of the BTLE interface in a low-power mode during at least the retransmission event. In the low-power mode, the second data channel PDU transmitted from the transmitting electronic device during the retransmission event is ignored and not received in the receiving electronic device.

0019In some embodiments, when the first data channel PDU and/or the second data channel PDU was received with the data D in the correct condition, the receiving electronic device is configured to transmit a third data channel PDU to the transmitting electronic device from the receiving electronic device using the BTLE interface in a sending window for the receiving electronic device during at least one of the regular event or the retransmission event, wherein the third data channel PDU comprises a payload with an acknowledgement message that acknowledges that the data D was in the correct condition.

0020In some embodiments, when determining if the first data channel PDU was received successfully, the receiving electronic device is configured to perform one or more operations to check if the data D transmitted by the transmitting electronic device in the payload of the first data channel PDU matches the data D received by the receiving electronic device in the payload of the first data channel PDU. In some embodiments, performing the one or more operations to check comprises comparing a computed cyclic redundancy check (ECC) value for the first data channel PDU with a CRC value in a field in the first data channel PDU.

BRIEF DESCRIPTION OF THE FIGURES

0021<figref idref="DRAWINGS">FIG. 1</figref> presents an example of a BTLE event-based communication scheme.

0022<figref idref="DRAWINGS">FIG. 2</figref> presents a block diagram of an electronic device in accordance with the described embodiments.

0023<figref idref="DRAWINGS">FIG. 3</figref> presents a block diagram of an assistive-listening device in accordance with the described embodiments.

0024<figref idref="DRAWINGS">FIG. 4</figref> presents a block diagram illustrating a system in accordance with the described embodiments.

0025<figref idref="DRAWINGS">FIG. 5</figref> presents a block diagram illustrating an exemplary data channel PDU in accordance with the described embodiments.

0026<figref idref="DRAWINGS">FIG. 6</figref> presents a block diagram illustrating an expanded view of a header for a data channel PDU in accordance with the described embodiments.

0027<figref idref="DRAWINGS">FIG. 7</figref> presents a block diagram of a Bluetooth Low Energy protocol stack in accordance with the described embodiments.

0028<figref idref="DRAWINGS">FIG. 8</figref> presents a block diagram illustrating an audio subsystem in accordance with the described embodiments.

0029<figref idref="DRAWINGS">FIG. 9</figref> presents a timeline diagram of communication between devices in accordance with the described embodiments.

0030<figref idref="DRAWINGS">FIG. 10</figref> presents a flowchart that illustrates a process for configuring an electronic device and an assistive-listening device for communicating audio in accordance with the described embodiments.

0031<figref idref="DRAWINGS">FIG. 11</figref> presents a flowchart illustrating a process for sending audio data from an electronic device using a BTLE network connection in accordance with the described embodiments.

0032<figref idref="DRAWINGS">FIG. 12</figref> presents a flowchart illustrating a process for receiving audio data in an assistive-listening device using the BTLE network connection in accordance with the described embodiments.

0033<figref idref="DRAWINGS">FIG. 13</figref> presents a timeline diagram illustrating an event-based communication scheme with retransmission events in accordance with the described embodiments.

0034<figref idref="DRAWINGS">FIG. 14</figref> presents a flowchart illustrating a process for communicating between an electronic device and an assistive-listening device using an event-based scheme with retransmission events in accordance with the described embodiments.

0035<figref idref="DRAWINGS">FIG. 15</figref> presents a flowchart illustrating a process for communicating between an electronic device and an assistive-listening device using an event-based scheme with retransmission events in accordance with the described embodiments.

0036In the figures, like reference numerals refer to the same figure elements.

DETAILED DESCRIPTION

0037The following description is presented to enable any person skilled in the art to make and use the described embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the described embodiments. Thus, the described embodiments are not limited to the embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein.

0038The data structures and code described in this detailed description can be stored on a computer-readable storage medium. The computer-readable storage medium can include any device or medium (or combination of devices and/or mediums) that can store data structures and code for use by a computer system/electronic device. For example, the computer-readable storage medium can include volatile memory or non-volatile memory, including flash memory, random access memory (RAM, SRAM, DRAM, RDRAM, DDR/DDR2/DDR3 SDRAM, etc.), magnetic or optical storage mediums (e.g., disk drives, magnetic tape, CDs, DVDs), or other mediums capable of storing data structures or code. Note that in the described embodiments, the computer-readable storage medium does not include non-statutory computer-readable storage mediums such as transmission signals.

0039The methods and processes described in the following description can be embodied as program code that is stored in a computer-readable storage medium. When a computer system (see, e.g., electronic device <b>200</b> in <figref idref="DRAWINGS">FIG. 2</figref> or assistive-listening device <b>300</b> in <figref idref="DRAWINGS">FIG. 3</figref>) reads and executes the program code stored on the computer-readable storage medium, the computer system performs the methods and processes in the program code stored in the computer-readable storage medium.

0040The methods and processes described in the following description can be included in hardware modules. For example, the hardware modules can include, but are not limited to, processors, application-specific integrated circuit (ASIC) chips, field-programmable gate arrays (FPGAs), and other programmable-logic devices. When the hardware modules are activated, the hardware modules perform the methods and processes included within the hardware modules. In some embodiments, the hardware modules include one or more general-purpose circuits that can be configured (e.g., by executing instructions) to perform the methods and processes. For example, in some embodiments, processing subsystem <b>202</b> (see <figref idref="DRAWINGS">FIG. 2</figref>) can acquire instructions from memory subsystem <b>204</b> and execute the instructions to cause processing subsystem <b>202</b> to perform the processes and operations in the described embodiments (the same is true for processing subsystem <b>302</b> and memory subsystem <b>304</b> in <figref idref="DRAWINGS">FIG. 3</figref>). In some embodiments, the instructions are firmware.

Overview

0041The described embodiments use a modified version of the Bluetooth Low Energy standard (herein referred to as “BTLE”) to communicate between electronic devices. The existing BTLE standard is described in the Core v. 4.0 Specification for the Bluetooth System from the Bluetooth Special Interest Group (SIG) of Kirkland, Wash., which was published on 30 Jun. 2010. The Core v. 4.0 Specification for the Bluetooth System is hereby incorporated by reference to describe the aspects of the BTLE standard that are not herein described (and is hereinafter interchangeably referred to as “the BTLE specification”).

0042The BTLE standard as described in the Bluetooth Specification does not include the capability to transfer and process audio data. However, the described embodiments comprise an improved version of the BTLE standard that enables the transfer and processing of audio data. The improved version of the BTLE standard in the described embodiments comprises: (1) an updated type of protocol data units (“PDUs” or “messages”); (2) a modified version of the BTLE protocol stack; and (3) additional control/configuration mechanisms, which are used to enable the transfer and processing of audio between electronic devices.

0043In some embodiments, a predetermined field in data channel PDUs is used to indicate to a receiver of the data channel PDU that the data in the payload portion of the data channel PDU is audio data. In some embodiments, the field in the data channel PDU can be an existing field such as the link-layer ID (LLID) field in which a value is written to distinguish the data channel PDU with audio data in the payload from other data channel PDUs (e.g., to distinguish the audio PDU from LL data PDUs and LL control PDUs).

0044In some embodiments, the modified version of the BTLE protocol stack includes an audio layer. The audio layer is a layer located above the link layer in the protocol stack that accepts digitally encoded audio data from the link layer for processing. In the described embodiments, upon receiving a data channel PDU for which the predetermined field is set to indicate that the payload is audio data, the link layer forwards the payload/audio data directly to the audio layer for subsequent processing. In some embodiments, the audio layer and/or applications above the audio layer can perform one or more processing steps to generate an analog signal from audio data in payloads of data channel PDUs, and a transducer can be used to output a signal generated from the analog signal.

0045In some embodiments, the control mechanisms include mechanisms that enable a transmitting device and a receiving device to communicate information about the capabilities of the transmitting device and/or the receiving device so that the transmitting device and/or receiving device can configure the audio data or the other device for transmission, decoding, and/or playback on the receiving device.

0046The described embodiments also comprise a modification to the BTLE event-based communication scheme that enables devices to avoid some of the effects of interference or data loss/corruption when communicating with other devices. Specifically, in the described embodiments, the event-based communication scheme of BTLE is modified to include additional “retransmission events” that are used to perform an automatic retransmission of data. In these embodiments, when retransmitting the data, the data is retransmitted at a different frequency than the frequency at which the data was originally transmitted to help avoid some of the effects of interference.

0047In the described embodiments, the event-based communication scheme comprises two different types of events: “regular” events and “retransmission” events. During a regular event, data is initially sent from a first device (e.g., higher-power device such as a smart phone) to a second device (e.g., a lower-power device such as a hearing aid) using a corresponding frequency agreed upon by the devices. (Note that regular events are similar to the events shown in <figref idref="DRAWINGS">FIG. 1</figref>.) During a retransmission event, the same data is resent from the first device to the second device, but using a different frequency agreed upon by the devices. In the described embodiments, the data can be resent by the first device during the retransmission event automatically, i.e., without receiving a request from the second device.

0048Regular events occur at a given interval agreed upon by the devices, and retransmission events are configured to occur between at least some of the regular events. Thus, a given regular event occurs at a time T₀and the corresponding retransmission event can occur at a time T₀+N, which is between the regular event and a next regular event.

0049In some embodiments, if the data is successfully received during the regular event, the second device can ignore the retransmission event. Hence, the second device may place portions of certain subsystems (e.g., radios or other interface mechanisms) in a low-power mode immediately following the regular event. In this way, the second device has two opportunities to receive the data—the regular event and the retransmission event, but can selectively listen for the data during the retransmission event.

Electronic Device and Assistive-Listening Device

0050<figref idref="DRAWINGS">FIG. 2</figref> presents a block diagram of electronic device <b>200</b> in accordance with the described embodiments. Electronic device <b>200</b> includes processing subsystem <b>202</b>, memory subsystem <b>204</b>, and networking subsystem <b>206</b>.

0051Processing subsystem <b>202</b> can include one or more devices configured to perform computational operations. For example, processing subsystem <b>202</b> can include, but is not limited to, one or more microprocessors, ASICs, microcontrollers, or programmable-logic devices.

0052Memory subsystem <b>204</b> can include one or more devices for storing data and/or instructions for processing subsystem <b>202</b> and networking subsystem <b>206</b>. For example, memory subsystem <b>204</b> can include DRAM, flash memory, and/or other types of memory. In addition, memory subsystem <b>204</b> can include mechanisms for controlling access to the memory. In some embodiments, memory subsystem <b>204</b> includes a memory hierarchy that includes an arrangement of one or more caches coupled to a memory for electronic device <b>200</b>. In some of these embodiments, one or more of the caches is located in processing subsystem <b>202</b>.

0053In some embodiments, memory subsystem <b>204</b> is coupled to one or more high-capacity mass-storage devices (not shown). For example, memory subsystem <b>204</b> can be coupled to a magnetic or optical drive, a solid-state drive, or another type of mass-storage device. In these embodiments, memory subsystem <b>204</b> can be used by electronic device <b>200</b> as fast-access storage for often-used data, while the mass-storage device is used to store less frequently used data.

0054Networking subsystem <b>206</b> can include one or more devices configured to couple to and communicate on a wired and/or wireless network (i.e., to perform network operations). For example, networking subsystem <b>206</b> can include, but is not limited to, a Bluetooth networking system (including support for the BTLE standard), a cellular networking system (e.g., a 3G/4G network), a universal serial bus (USB) networking system, a networking system based on the standards described in Institute for Electrical and Electronic Engineers (IEEE) 802.11 (i.e., an 802.11 wireless network), an Ethernet networking system, or a wired or wireless personal-area networking (PAN) system (e.g., an infrared data association (IrDA), ultra-wideband (UWB), Z-Wave, or a network based on the standards described in IEEE 802.15).

0055Networking subsystem <b>206</b> can include controllers, radios/antennas for wireless network connections, sockets/plugs for hard-wired electrical connections, and/or other devices used for coupling to, communicating on, and handling data and events on a wired and/or wireless network. In some of these embodiments, networking subsystem <b>206</b> can include one or more mechanisms for forming an ad hoc network connection with other devices. In the following description, we refer to a subset of the mechanisms used for coupling to, communicating on, and handling data and events on the network at the physical layer of each network connection collectively as the “interface” for the corresponding network connection.

0056Within electronic device <b>200</b>, processing subsystem <b>202</b>, memory subsystem <b>204</b>, and networking subsystem <b>206</b> are coupled together using bus <b>310</b>. Bus <b>310</b> is an electrical connection that processing subsystem <b>202</b>, memory subsystem <b>204</b>, and networking subsystem <b>206</b> use to communicate commands and data to each other. Although only one bus <b>310</b> is shown for clarity, different embodiments can include a different number or configuration of electrical connections between the subsystems.

0057Electronic device <b>200</b> can be, or can be incorporated into, many different types of electronic devices. Generally, these electronic devices include any device that can communicate data to a receiving device. For example, electronic device <b>200</b> can be part of a desktop computer, a laptop computer, a server, a media player, an appliance, a subnotebook/netbook, a tablet computer, a smart phone, a piece of testing equipment, a network appliance, a set-top box, a personal digital assistant (PDA), a toy, a controller, and/or another device.

0058Although specific components are used to describe electronic device <b>200</b>, in alternative embodiments, different components and/or subsystems may be present in electronic device <b>200</b>. For example, electronic device <b>200</b> may include one or more additional processing subsystems <b>202</b>, memory subsystems <b>204</b>, and/or networking subsystems <b>206</b>. Alternatively, one or more of the subsystems may not be present in electronic device <b>200</b>. Moreover, although separate subsystems are shown in <figref idref="DRAWINGS">FIG. 2</figref>, in some embodiments, some or all of a given subsystem can be integrated into one or more of the other subsystems in electronic device <b>200</b>.

0059In some embodiments, electronic device <b>200</b> may include one or more additional subsystems that are not shown in <figref idref="DRAWINGS">FIG. 1</figref>. For example, electronic device <b>200</b> can include, but is not limited to, a display subsystem for displaying information on a display, a data collection subsystem, an audio subsystem, an alarm subsystem, a media processing subsystem, and/or an input/output (I/O) subsystem.

0060<figref idref="DRAWINGS">FIG. 3</figref> presents a block diagram of an assistive-listening device <b>300</b> in accordance with the described embodiments. Generally, assistive-listening device <b>300</b> is an electronic device enables the person to perceive sound (i.e., hear or otherwise be aware of the sound). Assistive-listening device <b>300</b> includes processing subsystem <b>302</b>, memory subsystem <b>304</b>, networking subsystem <b>306</b>, and audio subsystem <b>308</b>.

0061Processing subsystem <b>302</b> can include one or more devices configured to perform computational operations. For example, processing subsystem <b>302</b> can include, but is not limited to, one or more processors, ASICs, microcontrollers, digital signal processors, or programmable-logic devices.

0062Memory subsystem <b>304</b> can include one or more devices for storing data and/or instructions for processing subsystem <b>302</b> and networking subsystem <b>306</b>. For example, memory subsystem <b>304</b> can include DRAM, flash memory, and/or other types of memory. In addition, memory subsystem <b>304</b> can include mechanisms for controlling access to the memory. In some embodiments, memory subsystem <b>304</b> includes a memory hierarchy that includes an arrangement of one or more caches coupled to a memory for assistive-listening device <b>300</b>. In some of these embodiments, one or more of the caches is located in processing subsystem <b>302</b>.

0063Networking subsystem <b>306</b> can include one or more devices configured to couple to and communicate on a wired and/or wireless network (i.e., to perform network operations). For example, networking subsystem <b>306</b> can include, but is not limited to, a Bluetooth networking system (including support for the BTLE standard), a cellular networking system (e.g., a 3G/4G network), a networking system based on the standards described in Institute for Electrical and Electronic Engineers (IEEE) 802.11 (i.e., an 802.11 wireless network), or a wireless personal-area networking (PAN) system (e.g., an infrared data association (IrDA), ultra-wideband (UWB), Z-Wave, or a network based on the standards described in IEEE 802.15).

0064Networking subsystem <b>306</b> can include controllers, radios/antennas for wireless network connections, sockets/plugs for hard-wired electrical connections, and/or other devices used for coupling to, communicating on, and handling data and events on a wired and/or wireless network. In some of these embodiments, networking subsystem <b>306</b> can include one or more mechanisms for forming an ad hoc network connection with other devices.

0065In some embodiments, the Bluetooth networking system in networking subsystem <b>306</b> is configured as a single-mode Bluetooth networking system, whereas in other embodiments, the Bluetooth networking system in networking subsystem <b>306</b> is configured as a dual-mode Bluetooth networking system.

0066Audio subsystem <b>308</b> can include one or more transducers configured to generate and/or output signals that a user of assistive-listening device <b>300</b> can perceive as sound. For example, audio subsystem <b>308</b> can include speakers, amplifiers, drivers, vibrating mechanisms, lights, and/or other transducers. Additionally, in some embodiments, audio subsystem <b>308</b> includes one or more decoder circuits, transcoder circuits, converter circuits, and/or other devices for processing audio data.

0067In some embodiments, processing subsystem <b>302</b> provides an analog signal (e.g., on bus <b>312</b>) that audio subsystem <b>308</b> uses to generate an output sound. In alternative embodiments, processing subsystem <b>302</b> provides a digital signal that audio subsystem <b>308</b> decodes or otherwise processes to generate one or more signals for generating an output sound.

0068Within assistive-listening device <b>300</b>, processing subsystem <b>302</b>, memory subsystem <b>304</b>, and networking subsystem <b>306</b> are coupled together using bus <b>310</b>, and processing subsystem <b>302</b> and audio subsystem <b>308</b> are coupled together using bus <b>312</b>. Bus <b>310</b> is an electrical connection that processing subsystem <b>302</b>, memory subsystem <b>304</b>, and networking subsystem <b>306</b> can use to communicate commands and data to each other, and bus <b>312</b> is an electrical connection that processing subsystem <b>302</b> and audio subsystem <b>308</b> can use to communicate commands and data to each other. Although busses <b>310</b> and <b>312</b> are shown for clarity, different embodiments can include a different number and/or configuration of electrical connections. Generally, assistive-listening device <b>300</b> comprises sufficient electrical connections to enable processing subsystem <b>302</b>, memory subsystem <b>304</b>, networking subsystem <b>306</b>, and audio subsystem <b>308</b> to communicate with one another as necessary.

0069Assistive-listening device <b>300</b> can be, or can be incorporated into many different types of electronic devices. Generally, these electronic devices include any device that a person can use to assist with the perception of sound. For example, assistive-listening device <b>300</b> can be a hearing aid, a cochlear implant, a vibrating device, a speaker, a headphone (or a pair of headphones), a display device, a tactile device, and/or another device.

0070Although we use specific components to describe assistive-listening device <b>300</b>, in alternative embodiments, different components and/or subsystems may be present in assistive-listening device <b>300</b>. For example, assistive-listening device <b>300</b> may include one or more additional processing subsystems <b>302</b>, memory subsystems <b>304</b>, and/or networking subsystems <b>306</b>. Alternatively, one or more of the subsystems may not be present in assistive-listening device <b>300</b>. Moreover, although separate subsystems are shown in <figref idref="DRAWINGS">FIG. 3</figref>, in some embodiments, some or all of a given subsystem can be integrated into one or more of the other subsystems in assistive-listening device <b>300</b>.

0071In some embodiments, assistive-listening device <b>300</b> may include one or more additional subsystems that are not shown in <figref idref="DRAWINGS">FIG. 3</figref>. For example, assistive-listening device <b>300</b> can include, but is not limited to, a data collection subsystem, a display subsystem, and/or an input/output (I/O) subsystem. In some embodiments, assistive-listening device <b>300</b> includes one or more batteries (not shown) that provide power for assistive-listening device <b>300</b>.

0072In some embodiments, assistive-listening device <b>300</b> can be a low-power device. In these embodiments, some or all of processing subsystem <b>302</b>, memory subsystem <b>304</b>, networking subsystem <b>306</b>, and audio subsystem <b>308</b> can be configured as low-power mechanisms. For example, processing subsystem <b>302</b> can be a low-power processing mechanism and/or a processing mechanism with limited functionality. Moreover, in some embodiments, processing subsystem <b>302</b>, memory subsystem <b>304</b>, networking subsystem <b>306</b>, and audio subsystem <b>308</b> can be custom-built to perform the indicated functions (processing, storing instructions and/or data, etc.) in assistive-listening device <b>300</b>, e.g., can be custom ASICs.

0073In some embodiments, assistive-listening device <b>300</b> is worn or otherwise carried by a user (not shown) and provides assistance to the user in perceiving selected sound(s). For example, assistive-listening device <b>300</b> can be worn or implanted in the ear as a hearing aid and/or can be worn as a headphone or headphones with the appropriate mounting hardware (straps, frames, adhesives, fasteners, etc.), can be carried in hand or worn on the body, and/or can otherwise be made available to the user.

0074<figref idref="DRAWINGS">FIG. 4</figref> presents a block diagram illustrating a system in accordance with the described embodiments. As can be seen in <figref idref="DRAWINGS">FIG. 4</figref>, wireless signals <b>402</b> are transmitted from a radio <b>400</b> (e.g., in networking subsystem <b>206</b>) in electronic device <b>200</b>. Wireless signals <b>402</b> are received by the corresponding network interface in networking subsystem <b>306</b> in assistive-listening device <b>300</b> and processed by networking subsystem <b>306</b> and/or processing subsystem <b>302</b> in assistive-listening device <b>300</b>. Although not shown in <figref idref="DRAWINGS">FIG. 4</figref>, wireless signals can also be transmitted from a radio in assistive-listening device <b>300</b> and received by radio <b>400</b> (or another radio in electronic device <b>200</b>). Generally, sufficient wireless signals are communicated between electronic device <b>200</b> and assistive-listening device <b>300</b> to enable the formation and maintenance of a BTLE network connection and the communication of data (e.g., audio data) between electronic device <b>200</b> and assistive-listening device <b>300</b>.

0075Note that although we describe embodiments using assistive-listening device <b>300</b>, alternative embodiments use two electronic devices <b>200</b> and/or other devices. Generally, the described embodiments can use any pair of devices where one device is a transmitter of audio data and the other device is a receiver of audio data. In addition, in some embodiments, two separate connections can be established with electronic device <b>100</b> if a user has two assistive-listening devices <b>200</b> (e.g., one for each ear).

Data Channel Protocol Data Unit (PDU)

0076<figref idref="DRAWINGS">FIG. 5</figref> presents a block diagram illustrating an exemplary data channel PDU <b>500</b> in accordance with the described embodiments. As shown in <figref idref="DRAWINGS">FIG. 5</figref>, data channel PDU <b>500</b> comprises header <b>502</b> and payload <b>504</b>, in addition to preamble (PREA <b>506</b>), access address (ADDR <b>508</b>), and CRC <b>510</b>. In the described embodiments, a field in header <b>502</b> is used to indicate whether payload <b>504</b> contains audio data (or contains some other data). More generally, with the exception of the uses herein described, the fields in data channel PDU <b>500</b> are used as described in the BTLE specification.

0077<figref idref="DRAWINGS">FIG. 6</figref> presents a block diagram illustrating an expanded view of a header <b>502</b> for a data channel PDU <b>500</b> in accordance with the described embodiments. As can be seen in <figref idref="DRAWINGS">FIG. 6</figref>, header <b>502</b> comprises the following fields: LLID <b>600</b>, NESN <b>602</b>, SN <b>604</b>, MD <b>606</b>, RFU <b>608</b>, LENGTH <b>610</b>, and RFU <b>612</b>. These fields are generally similar to data channel PDU header fields that are known in the art and hence their functions (aside from the functions herein described) are not described in detail.

0078Unlike the existing BTLE standard, in some embodiments, the LLID <b>600</b> field can be used to indicate whether payload <b>504</b> of data channel PDU <b>500</b> contains audio data. The LLID <b>600</b> field is a two-bit field that is used in existing implementations of the BTLE standard to indicate whether the PDU is an LL data PDU or an LL control PDU. Because only 3 combinations of the two-bit LLID <b>600</b> field are used in making this indication, the described embodiments employ a previously-unused combination of the bits of the LLID <b>600</b> field (i.e., combination “00”) to indicate that payload <b>504</b> contains audio data. Thus, in these embodiments, the type of data channel PDU <b>500</b> can be indicated as follows using the possible combinations in the LLID <b>600</b> field:

007900—Audio data;

008001—LL data PDU;

008110—LL data PDU; or

008211—LL control PDU.

0083When the LLID <b>600</b> field is set to 00, thereby indicating that audio data is present in payload <b>504</b>, the logical link <b>704</b> layer (see <figref idref="DRAWINGS">FIG. 7</figref>) in protocol stack <b>700</b> can forward data from payload <b>504</b> to the audio <b>712</b> layer for processing. Note that forwarding payload <b>504</b> to audio <b>712</b> layer is an operation that was previously not possible in implementations of the BTLE standard both because there was no audio <b>712</b> layer, and because the 00 value of the LLID <b>600</b> field was unused.

0084Note that, although we describe header <b>502</b> using the illustrated fields, in some embodiments, header <b>502</b> contains a different number, arrangement, and/or type of fields. Generally, header <b>502</b> contains sufficient data for a receiving device (e.g., assistive-listening device <b>300</b>) to determine whether or not the payload of the PDU contains audio data.

0085In some embodiments, when data channel PDU <b>500</b> contains audio data, the entire payload <b>504</b> can be audio data. That is, there may be no header or other information for audio <b>712</b> layer in payload <b>504</b>. Because this is true, these embodiments can increase the amount of audio data that is included in a given data channel PDU <b>500</b>, thereby reducing the amount of BTLE network traffic required to transfer the audio data and/or increasing the amount of audio data that can be transferred in a given amount of time (which can mean that the audio quality can be improved). In addition, the some embodiments can use the maximum number of bits (i.e., the maximum payload size) allowed for a payload when transmitting audio data. For example, in some embodiments the maximum payload size is 31 octets of audio data (note that the LENGTH <b>510</b> field in header <b>402</b> can indicate a length/number of octets in payload <b>404</b>).

Protocol Stacks

0086In the described embodiments, electronic device <b>200</b> includes one or more protocol stacks that are used to manage the transfer of data to and from electronic device <b>200</b> using an appropriate interface in networking subsystem <b>206</b>. For example, an operating system (not shown) executing on electronic device <b>200</b> can include software mechanisms that manage the transfer of data to and from the network interfaces in networking subsystem <b>206</b> for applications executing on electronic device <b>200</b>. Each of the protocol stacks included in electronic device <b>200</b> includes a number of logical layers. For example, electronic device <b>200</b> can maintain a BTC/BTLE protocol stack that comprises a physical RF layer, a baseband (BB) layer, a link (LL) layer, an L2CAP layer, etc. At each layer of a given protocol stack, electronic device <b>200</b> includes hardware and/or software mechanisms for performing the functions associated with the layer.

0087Assistive-listening device <b>300</b> also includes one or more protocol stacks that are used to manage the transfer of data to and from assistive-listening device <b>300</b> using an appropriate interface in networking subsystem <b>306</b>. For example, an operating system, a controller, and/or firmware (not shown) executing on assistive-listening device <b>300</b> can include software mechanisms that manage the transfer of data to and from the network interfaces in networking subsystem <b>306</b> for applications executing on assistive-listening device <b>300</b> and/or for other hardware mechanisms (e.g., an audio data processor and/or digital-to-analog converter) in assistive-listening device <b>300</b>.

0088<figref idref="DRAWINGS">FIG. 7</figref> presents a block diagram of a BTLE protocol stack <b>700</b> in assistive-listening device <b>300</b> in accordance with the described embodiments. Note that protocol stack <b>700</b> shown in <figref idref="DRAWINGS">FIG. 7</figref> differs from existing BTLE protocol stacks because protocol stack <b>700</b> includes the audio <b>712</b> layer, and can therefore handle audio data, as is herein described.

0089As can be seen in <figref idref="DRAWINGS">FIG. 7</figref>, protocol stack <b>700</b> comprises a number of different hardware and software mechanisms, including the LE PHY <b>702</b> layer, which is the physical/hardware layer of the BTLE protocol stack, and the logical link <b>704</b> and L2CAP <b>706</b> layers, that are implemented in software/firmware (e.g., executed by processing subsystem <b>302</b> and/or networking subsystem <b>306</b>). Protocol stack <b>700</b> also includes ports <b>708</b>, which serve as interfaces between protocol stack <b>700</b> and applications <b>710</b> executing on assistive-listening device <b>300</b>. (Note that the “applications <b>710</b>” may simply be functions of the operating system/firmware/controller in assistive-listening device <b>300</b>, and may not be standalone applications such as in more complex electronic devices). Aside from the functions herein described, the functions performed by the layers of protocol stack <b>700</b> are generally known in the art and hence are not described.

0090Audio <b>712</b> layer is a software mechanism executed by processing subsystem <b>302</b> that is configured to process incoming audio data. Generally, the logical link <b>704</b> layer reads incoming data channel PDUs <b>400</b> to determine if the data channel PDUs <b>400</b> contain audio data, and, if not, logical link <b>704</b> layer can process data channel PDU <b>500</b> accordingly. Otherwise, if the data channel PDUs <b>400</b> contain audio data, logical link <b>704</b> layer can forward data in payload <b>504</b> from the data channel PDU <b>500</b>s to audio <b>712</b> layer for subsequent processing (e.g., as an audio stream). The subsequent processing is described in more detail below.

0091In some embodiments, the network protocol stacks in electronic device <b>100</b> and assistive-listening device <b>200</b> provide applications on electronic device <b>100</b> and assistive-listening device <b>200</b> access to the attribute protocol (ATT) and generic attribute protocol (GATT), as are known in the art. In some of these embodiments, assistive-listening device <b>200</b> can function as a GATT server, and electronic device <b>100</b> can function as a GATT client and can access (read, write, modify) data in assistive-listening device <b>200</b>.

0092In some embodiments, device discovery and connection establishment between electronic device <b>100</b> and assistive-listening device <b>200</b> follows the BTLE specification. In some of these embodiments, electronic device <b>100</b> can take on the role of “central” and assistive-listening device <b>200</b> the role of “peripheral.” For example, assistive-listening device <b>200</b> can send an advertisement PDU with advertisement data periodically using an advertising interval of N seconds (e.g., 1-5 seconds), with a UUID for assistive-listening device <b>200</b> included in the advertising data.

Audio Subsystem

0093<figref idref="DRAWINGS">FIG. 8</figref> presents a block diagram illustrating audio subsystem <b>308</b> in assistive-listening device <b>300</b> in accordance with the described embodiments.

0094As can be seen in <figref idref="DRAWINGS">FIG. 8</figref>, audio subsystem <b>308</b> comprises an audio data processor <b>800</b>, a digital-to-analog converter (DAC) <b>802</b>, and a transducer <b>804</b>. Audio data processor <b>800</b> is configured to perform operations to generate processed digital data from data received from audio <b>712</b> layer. The processed digital data is then forwarded from audio data processor <b>800</b> to DAC <b>802</b>, where an analog signal is generated from the processed digital data. The analog signal is sent to transducer <b>804</b> for generation of signals (sound, vibrations, etc.) that can be perceived as sound by a user of assistive-listening device <b>300</b>.

0095In the described embodiments, in electronic device <b>200</b>, audio data can be compressed, encoded, and/or otherwise processed before a data channel PDU <b>500</b> is generated from the audio data. For example, in some embodiments, the processing can be performed to reduce the overall bit-length/size of the audio data to enable the audio data to be transmitted in as few data channel PDUs <b>400</b> as possible, while still maintaining a predetermined audio quality level (here, “quality level” is defined as an ability of a listener to perceive given aspects of an output audio signal generated from the audio data). In some embodiments, the processing comprises G.711, G. 722, G.722.1, and/or G. 726 encoding, MP3 encoding, and/or AAC-ELD encoding.

0096Because audio data received from electronic device <b>200</b> is encoded, compressed, and/or otherwise processed, audio data processor <b>800</b> can perform one or more operations to restore the audio signal from the received audio data and/or process the received audio data. For example, audio data processor <b>800</b> can decode, transcode, convert, amplify, normalize, shape, attenuate, reconfigure, customize, and/or otherwise process the audio data. In some embodiments, this processing includes G.711/G.726/G.722/G.722.1 decoding, MP3 decoding, and/or AAC decoding

0097Transducer <b>804</b> generally comprises any device or combination of devices that can output a signal that can be perceived as a sound and/or as a proxy for sound by a person using assistive-listening device <b>300</b>. For example, transducer <b>804</b> can be a speaker, a vibrator, an electrical signal generator, a visual signal generator, a tactile signal generator, and/or another device that can output sound, electrical, vibration, visual, tactile, and/or other types of signals.

0098Although an arrangement of functional blocks is shown in <figref idref="DRAWINGS">FIG. 8</figref>, in some embodiments, some or all of the functional blocks are included in other functional blocks and/or are included elsewhere in assistive-listening device <b>300</b>. For example, audio data processor <b>800</b> and/or DAC <b>802</b> can be included in the audio <b>712</b> layer of the protocol stack. Moreover, in some embodiments, some or all of audio subsystem <b>308</b> can be included in processing subsystem <b>302</b> and/or networking subsystem <b>306</b>, i.e., the functions being described as being performed by audio subsystem <b>308</b> can be performed by general-purpose circuits in processing subsystem <b>302</b> when processing subsystem <b>302</b> executes program code and/or firmware.

Communication Between Devices

0099<figref idref="DRAWINGS">FIG. 9</figref> presents a timeline diagram of communication between devices in accordance with the described embodiments. More specifically, <figref idref="DRAWINGS">FIG. 9</figref> presents a timeline diagram of communications between electronic device <b>200</b> and assistive-listening device <b>300</b> using an event-based communication scheme. The communication shown in <figref idref="DRAWINGS">FIG. 9</figref> occurs after a BTLE network connection has been established between electronic device <b>200</b> and assistive-listening device <b>300</b> using techniques known in the art.

0100In the described embodiments, connection interval <b>900</b> can be a predetermined length of time (and hence the events occur at a predetermined interval). For example, connection interval <b>900</b> can be 1 second long, 3 seconds long, etc. (or, more generally, any connection interval that is allowable in accordance with the BTLE standard).

0101In the described embodiments, the length of connection interval <b>900</b> can be dynamically set (i.e., set while electronic device <b>200</b> and assistive-listening device <b>300</b> are operating) to place the electronic device <b>200</b> and assistive-listening device <b>300</b> in a given mode. For example, in some embodiments, electronic device <b>200</b> and assistive-listening device <b>300</b> can operate in two modes, an active communication mode and a resting mode. During the resting mode, connection interval <b>900</b> can be a longer interval, e.g., 1 s, 2 s, etc., and during the active communication mode, connection interval <b>900</b> can be a shorter interval, e.g., 8 ms, 12 ms, 1 s, etc. These modes can be automatically configured (e.g., can be entered or exited at a given time or upon a predetermined event happening) and/or can be configured using the process described below with respect to <figref idref="DRAWINGS">FIG. 20</figref>.

0102Generally, during the active communication mode, connection interval <b>900</b> is configured to enable electronic device <b>200</b> and assistive-listening device <b>300</b> to communicate data (e.g., audio data, control/configuration data, and/or other data) at a predetermined rate. For example, if a bit-rate of N bits per second is to be used to transfer data, and a payload <b>504</b> of each data channel PDU <b>500</b> is at most K bits long, connection interval <b>900</b> can be set accordingly.

0103During the resting mode, connection interval <b>900</b> is configured to enable electronic device <b>200</b> and assistive-listening device <b>300</b> to consume less power than in the active communication mode, while still being sufficiently responsive to begin higher-speed communication data between electronic device <b>200</b> and assistive-listening device <b>300</b> when data becomes available. For example, assuming that electronic device <b>200</b> is a phone and assistive-listening device <b>300</b> is a hearing-aid, in the resting mode, connection interval <b>900</b> should be a short enough time to enable electronic device <b>200</b> and assistive-listening device <b>300</b> to respond in time to answer the phone call. More specifically, an event should happen sufficiently often to enable electronic device <b>200</b> to communicate to assistive-listening device <b>300</b> that the active communication mode is to be entered so that the phone call can be answered in a reasonable time (e.g., 1 second, 2 seconds, etc.).

0104As described below, the described embodiments may also include retransmission events during which a transmitting device (e.g., electronic device <b>200</b>) automatically resends data that was originally transmitted during a corresponding regular event. The retransmission events can be configured in a similar way to connection interval <b>900</b>. For example, in some embodiments, the timing of retransmission events adjusts along with the regular events (e.g., E<b>0</b> and E<b>1</b> in <figref idref="DRAWINGS">FIG. 9</figref>), keeping the retransmission events timed midway between the regular events. In other embodiments, the timing of retransmission events can be adjusted independently of regular events. For clarity, the retransmission windows are not shown in <figref idref="DRAWINGS">FIG. 9</figref>.

Configuration

0105As indicated above with respect to connection interval <b>900</b>, the described embodiments can dynamically configure aspects of the communication between electronic device <b>200</b> and assistive-listening device <b>300</b> and/or of the processing of data in electronic device <b>200</b> and assistive-listening device <b>300</b>. For example, in addition to connection interval <b>900</b>, in some embodiments, electronic device <b>200</b> and assistive-listening device <b>300</b> can configure the type of processing that is performed on the audio data that is communicated between electronic device <b>200</b> and assistive-listening device <b>300</b>. In these embodiments, the processing can include any of the above-described compression, encoding, transcoding converting, amplifying, normalizing, shaping, attenuating, reconfiguring, customizing, etc. The described embodiments can also configure other aspects, such as channels used, signal strengths, sending/receiving window length, etc.

0106For example, in some embodiments, electronic device <b>200</b> and assistive-listening device <b>300</b> can exchange data channel PDUs <b>400</b> to configure connection interval <b>900</b> as described above. In these embodiments, while operating in the active communication mode at runtime, electronic device <b>200</b> can determine that limited or no data is likely to be sent to assistive-listening device <b>300</b> for a given amount of time (e.g., 10 seconds, 1 minute, etc.), and can send a data channel PDU <b>500</b> at an appropriate event time to cause assistive-listening device <b>300</b> to enter the rest mode. Upon subsequently determining that data is to be sent to assistive-listening device <b>300</b>, electronic device <b>200</b> can send another data channel PDU <b>500</b> at an appropriate event time to cause assistive-listening device <b>300</b> to enter the active communications mode. When entering either mode, assistive-listening device <b>300</b> and electronic device <b>200</b> begin using the corresponding connection interval <b>900</b>. Note that, in some embodiments, the data channel PDU <b>500</b> in this example may be consumed/read at the logical link <b>704</b> layer and used to configure lower layers of protocol stack <b>700</b> (e.g., the radios, etc.).

0107As another example, in some embodiments, as one of the initial operations when preparing to communicate audio data, assistive-listening device <b>300</b> can send a data channel PDU <b>500</b> to electronic device <b>200</b> with a payload that indicates a type (or types) of audio processing that is (are) supported by audio data processor <b>800</b>. For example, assistive-listening device <b>300</b> can indicate what types of audio data decoding are supported. Electronic device <b>200</b> can then configure its audio processing accordingly, and, if assistive-listening device <b>300</b> supports multiple types of audio processing, e.g., multiple types of decoders, can indicate in a data channel PDU <b>500</b> to assistive-listening device <b>300</b> which data processing will be used. In this way, audio data processing aspects are configured before communication of audio data begins. Because configuration data need not be carried in the data stream after the initial configuration operations are completed, subsequent communication can include a larger proportion of audio data per payload (than systems that include configurations with audio data PDUs).

0108In some embodiments, when configuring the decoders (or “codecs”) that are to be used, electronic device <b>100</b> (the audio “source”—which can be the “master” on the BTLE link) can start by sending a prioritized list of codecs supported by electronic device <b>100</b> in a dedicated configuration PDU (a prioritized_supported_codec_list PDU) to assistive-listening device <b>200</b> (the audio “sink”—which can be the “slave” on the BTLE link). Assistive-listening device <b>200</b> can then respond to electronic device <b>100</b> with a prioritized list of codecs supported by assistive-listening device <b>200</b> using a prioritized_supported_codec_list PDU. Electronic device <b>100</b> next decides what codec to use and sends a confirmation configuration PDU (a select_codec PDU). (Note that, although we describe this exchange, some embodiments only perform a one-sided exchange during which a configuration PDU is sent from assistive-listening device <b>200</b> to electronic device <b>100</b> to enable electronic device <b>100</b> to determine the codecs supported by assistive-listening device <b>200</b>, one of which can be selected by electronic device <b>100</b>.)

0109In some embodiments, in the prioritized_supported_codec_list PDU, each codec can be numerically represented by a predetermined numeric codec ID (CoID) that is a predetermined fixed length. For example, in some embodiments, the CoID can be one octet in length, two octets in length, etc. In some embodiments, a maximum of N CoIDs (e.g., 22, 28, etc.) may be sent in a prioritized_supported_codec_list PDU. If more than N codecs are supported by a given device, a last octet in the prioritized_supported_codec_list PDU can be set to a predetermined value (e.g., 0, 255, etc.) to indicate that more codecs are supported. A subsequent prioritized_supported_codec_list PDU can then be sent with the remaining codecs—an operation that can be repeated until all supported codecs have been communicated from one device to the other.

0110In some embodiments, within a prioritized_supported_codec_list PDU, the codecs can be ordered in priority or preference order by the sender. For example, assuming a CoID of one octet, a first octet in a prioritized_supported_codec_list can contain the codec that the sender would most prefer using. The second octet, the sender's second choice and so on. In some embodiments, the prioritized_supported_codec_list PDU sent by assistive-listening device <b>200</b> can be ordered in accordance with the listing of the codecs in the prioritized_supported_codec_list PDU sent from electronic device <b>100</b> (i.e., assistive-listening device <b>200</b> can attempt to match the list to the extent possible, etc.).

0111In some embodiments, the select_codec PDU can comprise an octet (or octets) that list the CoID of the codec to be used (e.g., the codec selected by electronic device <b>100</b>). The select_codec PDU may also comprise additional codec-specific parameters.

0112As described herein, the codec may be changed during a communication session (i.e., while electronic device <b>100</b> and assistive-listening device <b>200</b> are communicating using a BTLE link). For example, in some embodiments, electronic device <b>100</b> can determine that a different codec from the list of codecs previously described by assistive-listening device <b>200</b> in a prioritized_supported_codec_list PDU is to be used. Before the different codec is used, electronic device <b>100</b> can send a PDU indicating that the audio stream is to be stopped, then send a select_codec PDU indicating the new codec to be used, and next restart the audio stream using the new codec. Note that, in some embodiments, assistive-listening device <b>200</b> may acknowledge the new codec before electronic device <b>100</b> starts using the codec.

0113In another example, of the configuration that can be performed, in some embodiments, electronic device <b>200</b> can configure aspects of the signals (sound, vibrations, light, etc.) that are output from transducer <b>804</b> in assistive-listening device <b>300</b>. In these embodiments, electronic device <b>200</b> can communicate data channel PDUs <b>400</b> to assistive-listening device <b>300</b> indicating that the signals that are output from transducer <b>804</b> should be modified in some way, including the above-described amplifying, normalizing, shaping, attenuating, reconfiguring, customizing, etc. In some of these embodiments, one or more applications <b>710</b> on assistive-listening device <b>300</b> can receive the payloads <b>404</b> from the data channel PDUs <b>400</b> communicated from electronic device <b>200</b> (e.g., from the L2CAP <b>706</b> layer through ports <b>708</b>), and can configure the audio <b>712</b> layer in protocol stack <b>700</b> and/or audio subsystem <b>308</b> to modify the signals output from transducer <b>804</b>.

0114In some of these embodiments, electronic device <b>200</b> can be configured to recognize when the signals that are output from transducer <b>804</b> should be modified in some way, and can be configured to communicate the modification to assistive-listening device <b>300</b>. In other embodiments, electronic device <b>200</b> can execute an application that provides a user interface that allows a local and/or remote user to configure the sound output from assistive-listening device <b>300</b>. For example, in some embodiments, a person can remotely log-in to electronic device <b>200</b> and use the interface to adjust the sound output by assistive-listening device <b>300</b> (where assistive-listening device <b>300</b> is a hearing aid).

0115Note that the described embodiments are not limited to configuration as an initial operation. In these embodiments, configuration is performed anytime, as necessary; including reconfiguration. Moreover, although we describe the prioritized_supported_codec_list PDU and the select_codec PDU as separate PDUs, in some embodiments, a dedicated, but generic configuration PDU is used for multiple operations, with a code set in the PDU for different functions. For example, along with codes for prioritized_supported_codec_list and select_codec, the configuration PDU can include codes for “start stream” and “stop stream” which indicate that the audio stream from the source (e.g., electronic device <b>100</b>) is to be started or stopped, “version,” etc.

0116<figref idref="DRAWINGS">FIG. 10</figref> presents a flowchart that illustrates a process for configuring electronic device <b>200</b> and assistive-listening device <b>300</b> for communicating audio data in accordance with the described embodiments. For this example, it is assumed that a BTLE network connection was previously established. Note that, although we use the operations shown in <figref idref="DRAWINGS">FIG. 10</figref> to describe the process, in alternative embodiments, the operations may be performed in a different order and/or more or fewer operations may be performed for configuring electronic device <b>200</b> and assistive-listening device <b>300</b> for communicating audio data.

0117As can be seen, the process in <figref idref="DRAWINGS">FIG. 10</figref> starts when electronic device <b>200</b> determines that audio data is to be sent to assistive-listening device <b>300</b> using a BTLE network connection (step <b>1000</b>). For example, an operating system in electronic device <b>200</b> can receive a request from an application to begin transferring audio data on the BTLE network connection or can otherwise determine that audio data is to be sent to assistive-listening device <b>300</b>. Electronic device <b>200</b> then sends one or more data channel PDUs <b>400</b> to assistive-listening device <b>300</b> to determine the types of audio data processing that are supported by assistive-listening device <b>300</b> (step <b>1002</b>). For example, electronic device <b>200</b> can send one or more requests to determine an audio decoder, an audio converter, an amplifier, an equalizer, and/or other types of audio processing provided by assistive-listening device <b>300</b>. In some embodiment, each data channel PDU <b>500</b> sent by electronic device <b>200</b> comprises one request (e.g., a request for types of decoders in assistive-listening device <b>300</b>). In alternative embodiments, electronic device <b>200</b> can send one or more compound requests to determine the types of audio data processing supported by assistive-listening device <b>300</b> (e.g., a single request for all types of data processing supported by assistive-listening device <b>300</b>).

0118Next, electronic device <b>200</b> receives one or more data channel PDUs <b>400</b> that comprise responses from assistive-listening device <b>300</b> indicating the types of audio data processing that are supported by assistive-listening device <b>300</b> (step <b>1004</b>). For example, electronic device <b>200</b> can receive one or more responses indicating that assistive-listening device <b>300</b> includes an AAC decoder and a particular type of equalizer.

0119Electronic device <b>200</b> then configures processing subsystem <b>202</b> and/or networking subsystem <b>206</b> to process audio data in accordance with the responses from assistive-listening device <b>300</b> when preparing audio data for transfer to assistive-listening device <b>300</b> (step <b>1006</b>). For example, assuming that the responses from assistive-listening device <b>300</b> indicate that the above-described AAC decoder is included in assistive-listening device <b>300</b>, electronic device <b>200</b> can configure processing subsystem <b>202</b> (or another mechanism in electronic device <b>200</b>) to encode audio data using the AAC encoding scheme.

0120Depending on the type of processing supported by assistive-listening device <b>300</b>, electronic device <b>200</b> may also subsequently send one or more data channel PDUs <b>400</b> to configure assistive-listening device <b>300</b> to perform audio processing in a given way (step <b>1008</b>). For example, assuming that assistive-listening device <b>300</b> indicates support for the above-described equalizer, electronic device <b>200</b> can send one or more data channel PDUs <b>400</b> to configure settings of the equalizer (e.g., to normalize the audio data in assistive-listening device <b>300</b>, etc.).

0121Note that, when electronic device <b>200</b> sends data channel PDUs <b>400</b> to assistive-listening device <b>300</b>, electronic device <b>200</b> can send any type of data channel PDUs <b>400</b> to assistive-listening device <b>300</b>. For example, electronic device <b>200</b> can send data channel PDUs <b>400</b> that are read/consumed by the logical link <b>704</b> layer for configuring lower levels of protocol stack <b>700</b>, can send data channel PDUs <b>400</b> that are read/consumed by the L2CAP <b>706</b> layer and forwarded to applications <b>710</b> for configuring assistive-listening device <b>300</b>, etc. The same is true for response data channel PDUs sent from assistive-listening device <b>300</b> to electronic device <b>200</b>.

0122In some embodiments, a user of an electronic device in communication with electronic device <b>100</b> (or another electronic device that is in communication with assistive-listening device <b>200</b>) can use the above-described data channel PDUs <b>400</b> to configure one or more operations performed by assistive-listening device <b>200</b> when processing audio data (e.g., equalization, amplification, etc.). For example, an audiologist, a parent, and/or another entity (including possibly a second electronic device, e.g., a computer system) can determine that audio data is to be processed in assistive-listening device <b>200</b> in a particular way, and can use a configuration application or web interface (e.g., on a home computer and/or in a doctor's office) to send corresponding data channel PDUs <b>400</b> with configuration information to assistive-listening device <b>200</b> (perhaps through electronic device <b>100</b>). This can include forming a network connection (Bluetooth, WiFi, PAN, etc.) with electronic device <b>100</b> from another electronic device, and using the herein-described mechanisms in electronic device <b>100</b> to communicate with assistive-listening device <b>200</b>.

0000Sending and Receiving Audio Data using the Bluetooth Low Energy Network Connection

0123<figref idref="DRAWINGS">FIG. 11</figref> presents a flowchart illustrating a process for sending audio data using a BTLE network connection from an electronic device <b>200</b> in accordance with the described embodiments. <figref idref="DRAWINGS">FIG. 12</figref> presents a flowchart illustrating a process for receiving audio data using the BTLE network connection in an assistive-listening device <b>300</b> in accordance with the described embodiments. For this example, it is assumed that the BTLE network connection was previously established and that the configuration operations described in <figref idref="DRAWINGS">FIG. 9</figref> have been performed. Although we use the operations shown in <figref idref="DRAWINGS">FIG. 11-12</figref> to describe these processes, in alternative embodiments, the operations may be performed in a different order and/or more or fewer operations may be performed.

0124Although we describe the configuration operations as having already been performed, in the described embodiments, configuration and audio data PDUs can be mixed, so that configuration PDUs are interleaved with audio PDUs, thereby enabling the dynamic re-configuration of assistive-listening device <b>200</b> and/or electronic device <b>100</b>. In some embodiments, the interleaved PDUs can contain information (e.g., sequence number bits, etc.) in header <b>402</b> that indicates that the PDUs are related to the processing of audio.

0125The process shown in <figref idref="DRAWINGS">FIG. 11</figref> starts when an application being executed by electronic device <b>200</b> or a circuit in electronic device <b>200</b> generates an analog audio signal to be sent to assistive-listening device <b>300</b> using the BTLE network connection (step <b>1100</b>). Electronic device <b>200</b> then determines the audio processing that is to be performed on the analog audio signal to generate a digital output that is to be sent to assistive-listening device <b>300</b> (step <b>1102</b>). As described above, this operation can involve determining which audio decoder, audio converter, amplifier, equalizer, and/or other type of audio processing are provided by assistive-listening device <b>300</b>, as indicated by one or more configuration settings in electronic device <b>200</b>.

0126Upon determining the audio processing that is to be performed on the analog audio signal, electronic device <b>200</b> performs the audio processing to generate the digital output (step <b>1104</b>). Electronic device <b>200</b> then assembles a data channel PDU <b>500</b> with a payload <b>504</b> that contains the digital output (step <b>1106</b>), and sets a value in a header <b>502</b> of the data channel PDU <b>500</b> to indicate that the payload <b>504</b> contains audio data (step <b>1108</b>). In the described embodiments, the audio processing and the assembly of the data channel PDU <b>500</b> can occur in different applications, layers of the protocol stack, etc. For example, in some embodiments, encoded audio data coming from a codec in electronic device <b>100</b> is treated as a stream and directly fed to the link layer (LL) of the Bluetooth protocol stack in electronic device <b>100</b>. The link layer (LL) can treat the stream as a real time stream (e.g., may flush data from this stream in case of link congestion, etc.).

0127Next, the electronic device <b>200</b> transmits the data channel PDU to the assistive-listening device <b>300</b> using the BTLE network connection (step <b>1110</b>). Note that the data channel PDU is transmitted from electronic device <b>200</b> upon the occurrence of a corresponding event (see <figref idref="DRAWINGS">FIG. 8</figref>), so that electronic device <b>200</b> is in a sending window, and is therefore permitted to transmit packets to assistive-listening device <b>300</b> using the BTLE network connection, and assistive-listening device <b>300</b> is in a receiving window, and is therefore listening for packets from electronic device <b>200</b> on the BTLE network connection. In some embodiments, the devices are in the active communication mode and the connection interval is configured accordingly. Additionally, in the described embodiments, electronic device <b>200</b> may retransmit the data channel PDU during a subsequent retransmission event, as is described in more detail below.

0128The process shown in <figref idref="DRAWINGS">FIG. 12</figref> starts when assistive-listening device <b>300</b> receives the data channel PDU <b>500</b> transmitted from electronic device <b>200</b> using the BTLE network connection (step <b>1200</b>). In the logical link <b>704</b> layer of BTLE protocol stack <b>700</b>, assistive-listening device <b>300</b> determines that the header <b>502</b> of the data channel PDU <b>500</b> indicates that the payload <b>504</b> of the data channel PDU <b>500</b> contains audio data (step <b>1202</b>). For example, the logical link <b>704</b> layer can read the header of the packet to determine if a predetermined field in the header <b>502</b> of the data channel PDU <b>500</b> indicates that the payload <b>504</b> contains audio data. In some embodiments, this can comprise reading the LLID to determine if the LLID is set to a predetermined value, e.g., 00.

0129Upon determining that the data channel PDU <b>500</b> contains audio data, the logical link <b>704</b> layer forwards the audio data from the payload <b>504</b> to an audio <b>712</b> layer of the BTLE protocol stack (step <b>1204</b>). Note that, in some embodiments, the entire payload <b>504</b> of the data channel PDU <b>500</b> is forwarded from the logical link <b>704</b> layer to the audio <b>712</b> layer. Audio <b>712</b> layer then sends the audio data to the appropriate part of an audio subsystem <b>308</b> for processing (step <b>1206</b>). In audio subsystem <b>308</b>, one or more operations are performed on the audio data from the payload <b>504</b> to generate processed digital audio data (step <b>1208</b>). For example, the audio data from payload <b>504</b> can be decoded, transcoded, equalized, normalized, modified, and/or otherwise processed. The processed digital audio data is then forwarded to a DAC <b>802</b> to be converted to an analog signal (step <b>1210</b>). From DAC <b>802</b>, the analog signal is then sent to transducer to be used to generate an output signal that can be perceived as sound (step <b>1212</b>).

0130Additionally, in the described embodiments, assistive-listening device <b>300</b> may receive the data channel PDU <b>500</b> during a retransmission event. In these embodiments, upon receiving the data channel PDU <b>500</b> during the retransmission event, assistive-listening device <b>300</b> processes the data channel PDU <b>500</b> as described above.

0131Although we describe the processes in <figref idref="DRAWINGS">FIGS. 11-12</figref> using electronic device <b>200</b> as the sending device and assistive-listening device <b>300</b> as the receiving device, in alternative embodiments, other combinations of devices can be used. For example, in some embodiments, two electronic devices <b>200</b> can perform the operations shown in <figref idref="DRAWINGS">FIGS. 11-12</figref>.

Retransmission of Data

0132The described embodiments use modified BTLE event-based communication scheme that enables electronic device <b>200</b> and assistive-listening device <b>300</b> to avoid some of the effects of interference or data loss/corruption when communicating with one another. Specifically, in the described embodiments, the event-based communication scheme of BTLE is modified by adding “retransmission events” during which a transmitting device automatically retransmits data. In these embodiments, when retransmitting the data during a retransmission event, the transmitting device retransmits the data at a different frequency than the frequency at which the data was originally transmitted during a corresponding regular event. A receiving device can determine if data was successfully received during a regular event and, if so, can ignore the retransmission of the data during the corresponding retransmission event. In this way, the receiving device has the opportunity to receive (or re-receive) the data, but the receiving device is not obligated to listen for the retransmitted data.

0133For clarity in the following description, we use electronic device <b>200</b> as a transmitting device and assistive-listening device <b>300</b> as a receiving device. However, in alternative embodiments, other combinations of devices are used. Generally, any set of devices that can communicate using the BTLE standard can be configured to use the event-based scheme with retransmission events herein described. For example, two electronic devices <b>200</b> can communicate with one another. In addition, in some embodiments, three or more devices may be configured to communicate with one another using similar techniques.

0134<figref idref="DRAWINGS">FIG. 13</figref> presents a timeline diagram illustrating an event-based communication scheme in accordance with the described embodiments. <figref idref="DRAWINGS">FIG. 13</figref> includes two timelines, one for electronic device <b>200</b> and the other for assistive listening device <b>300</b>, along with a key describing the different “windows” shown in <figref idref="DRAWINGS">FIG. 13</figref>. As can be seen in <figref idref="DRAWINGS">FIG. 13</figref>, the event-based scheme in the described embodiments comprises two different types of events: “regular” events and “retransmission” events. The regular events shown in <figref idref="DRAWINGS">FIG. 13</figref> include regular events E<b>0</b> and E<b>1</b>, and the retransmission events include retransmission event R<b>0</b>. In some embodiments, the regular events are similar to the “events” shown in <figref idref="DRAWINGS">FIG. 1</figref>. However, the retransmission events shown in <figref idref="DRAWINGS">FIG. 13</figref> are not implemented in the existing BTLE standard.

0135During a regular event, a PDU comprising data “D” is sent from electronic device <b>200</b> to assistive-listening device <b>300</b> (assuming that data D was available to be sent). More specifically, in electronic device <b>200</b>'s sending window during the regular event, electronic device <b>200</b> sends the PDU to assistive-listening device <b>300</b>, which is in a corresponding receiving window and is therefore listening for data from electronic device <b>200</b>. The data D sent in the PDU can generally be any type of data, e.g., the above-described audio data.

0136Additionally, during a regular event, a corresponding frequency is used to communicate between electronic device <b>200</b> and assistive-listening device <b>300</b>. More specifically, the Bluetooth interfaces (e.g., the radios, etc.) in electronic device <b>200</b> and assistive-listening device <b>300</b> are configured during the regular event to transmit and receive at the corresponding frequency. For example, for regular event E<b>0</b> frequency <b>1300</b> is used and for regular event E<b>1</b> frequency <b>1304</b> is used. In some embodiments, frequency <b>1300</b> is different than frequency <b>1304</b>. Generally, the frequencies used can be any frequency at which a radio is permitted to operate according to the limitations of the underlying interfaces. In some embodiments, the frequencies are further limited to frequencies allowable in accordance with the BTLE standard and other external standards and rules dictating operating frequencies for electronic devices, as are known in the art.

0137During a retransmission event, a PDU comprising data D is resent from electronic device <b>200</b> to assistive-listening device <b>300</b>. More specifically, in electronic device <b>200</b>'s retransmission window during the retransmission event, electronic device <b>200</b> sends the PDU to assistive-listening device <b>300</b>, which is in a corresponding receiving window and is therefore listening for data from electronic device <b>200</b>. The data D sent in the PDU during the retransmission event is the same data that was originally sent during a corresponding regular event. For example, for retransmission event R<b>0</b>, the data D is the same as was sent during corresponding regular event E<b>0</b>. As described above, resending the data during the retransmission event provides assistive-listening device <b>300</b> with an opportunity to receive or re-receive data that was not properly received during the corresponding regular event.

0138Additionally, during a retransmission event, a corresponding frequency is used to communicate between electronic device <b>200</b> and assistive-listening device <b>300</b>. More specifically, the Bluetooth interfaces (e.g., the radios, etc.) in electronic device <b>200</b> and assistive-listening device <b>300</b> are configured during the retransmission event to transmit and receive at the corresponding frequency. For example, for retransmission event R<b>0</b>, frequency <b>1302</b> is used. In the described embodiments, the frequency used during a retransmission event is different than the frequency used during the corresponding regular event. For example, frequency <b>1302</b> for retransmission event R<b>0</b> is different than frequency <b>1300</b> for corresponding regular event E<b>0</b>. As with regular events, the frequencies used during retransmission events can be any frequency at which a radio is permitted to operate according to the limitations of the underlying interfaces and/or the frequencies allowable in accordance with the BTLE standard and other external standards and rules dictating operating frequencies for electronic devices.

0139In the described embodiments, the regular events occur at a given connection interval <b>900</b>, and retransmission events are configured to occur between regular events. Thus, a given regular event occurs at a time T₀and the corresponding retransmission event occurs at a time T₀+N, which is between the regular event and a next regular event. For example, connection interval <b>900</b> can be 15 ms, and retransmission events can occur 7.5 ms after the corresponding regular event starts (i.e., mid-way between the regular events). Generally, any timing can be used for retransmission events with respect to regular events in accordance with the abilities of the Bluetooth interfaces in electronic device <b>200</b> and assistive-listening device <b>300</b> and the general timing limits (e.g., minimum time between events, etc.) for communications in the BTLE standard. In addition, as with connection interval <b>900</b>, in some embodiments, the time between a regular event and a corresponding retransmission event can be dynamically configured by electronic device <b>200</b> and/or assistive-listening device <b>300</b>.

0140In the described embodiments, a PDU comprising data D can be resent by electronic device <b>200</b> during the retransmission event automatically. For example, electronic device <b>200</b> can resend the PDU comprising data D without receiving a request from assistive-listening device <b>300</b>. In this way, assistive-listening device <b>300</b> can be assured that a PDU sent from electronic device <b>200</b> during a regular event will then be resent during a corresponding retransmission event, without a request message or other signal from assistive-listening device <b>300</b>.

0141In alternative embodiments, assistive-listening device <b>300</b> can send one or more messages to cause or prevent electronic device <b>200</b> from resending data during a retransmission event. For example, in some embodiments, assistive-listening device <b>300</b> can send an acknowledge message to acknowledge the successful receipt of data during a regular event, which causes electronic device <b>200</b> not to resend the data during the corresponding retransmission event.

0142In the described embodiments, if a PDU (and the data within the PDU) is successfully received during a regular event, assistive-listening device <b>300</b> can ignore the resending of the data from electronic device <b>200</b> during the corresponding retransmission event. More specifically, in its receiving window during a regular event, assistive-listening device <b>300</b> can receive a PDU with data D transmitted from electronic device <b>200</b>. Assistive-listening device <b>300</b> can then examine the data D to determine if the data was received in a correct condition. For example, in some embodiments, assistive-listening device <b>300</b> can compute a cyclic redundancy check (CRC) value for the PDU/data D and compare the CRC value to a CRC value included in the PDU to ensure that the values match and hence data D arrived correctly. When data D was received correctly, assistive-listening device <b>300</b> has no need for re-receiving the data, and hence assistive-listening device <b>300</b> can ignore the resending of the data from electronic device <b>200</b> during the corresponding retransmission event.

0143When “ignoring” the resending of the data from electronic device <b>200</b> during the corresponding retransmission event, the second device may place portions of certain subsystems (e.g., radios or other Bluetooth interface mechanisms) in a low-power mode immediately following the regular event in which data D was received successfully. This can help assistive-listening device <b>300</b> to avoid unnecessarily consuming power, and can therefore help assistive-listening device <b>300</b> preserve battery life.

0144In <figref idref="DRAWINGS">FIG. 13</figref>, a sending window is shown for assistive-listening device <b>300</b> and a receiving window is shown for electronic device <b>200</b> during retransmission event RO. However, the sending window for assistive-listening device <b>300</b> and the receiving window for electronic device <b>200</b> during the retransmission event are optional. These windows are optional because in some embodiments, no PDUs are transmitted from assistive-listening device <b>300</b> during a retransmission event. Thus, in some embodiments, a sending window is not used by assistive-listening device <b>300</b> during the retransmission event. However, in alternative embodiments, one or more messages may be transmitted from assistive-listening device <b>300</b> to electronic device <b>200</b> during the retransmission event. For example, an acknowledge or negative acknowledge message may be transmitted to electronic device <b>200</b> to ensure that electronic device <b>200</b> receives an indication that assistive-listening device <b>300</b> successfully received the data D (or did not).

0145In the described embodiments, if the data D is not successfully received during either the regular event or a retransmission event, the data may be again resent during a subsequent regular event. In some embodiments, the data is resent in the subsequent regular event using either the frequency of the retransmission event or the frequency of the prior regular event.

0146In some embodiments, because electronic device <b>200</b> is configured to automatically resend data during a retransmission window, assistive-listening device <b>300</b> need not acknowledge the receipt of data during the corresponding regular window. Because no acknowledge message need be sent, assistive-listening device <b>300</b> can power-down radios during a regular event without performing any transmit operations during the sending window for assistive-listening device <b>300</b> when there is no other data to be sent. In other words, as soon as data is successfully received in a receiving window during a regular event in assistive-listening device <b>300</b>, if there is no other data to be transmitted to electronic device <b>200</b>, assistive-listening device <b>300</b> can power down the radios in the Bluetooth interface.

0147<figref idref="DRAWINGS">FIG. 14</figref> presents a flowchart illustrating a process for communicating between electronic device <b>200</b> and assistive-listening device <b>300</b> using an event-based scheme with retransmission events in accordance with the described embodiments. Generally, the process shown in <figref idref="DRAWINGS">FIG. 14</figref> occurs after electronic device <b>200</b> and assistive-listening device <b>300</b> have initialized a BTLE network connection using operations known in the art. Note that initializing the BTLE network connection in the described embodiments comprises configuring a connection interval <b>900</b> (i.e., the timing of regular events), as well as the timing of retransmission events.

0148The process shown in <figref idref="DRAWINGS">FIG. 14</figref> starts when electronic device <b>200</b>, during a regular event (and in electronic device <b>200</b>'s sending window), transmits a first data channel PDU with a payload <b>504</b> that includes data D to assistive-listening device <b>300</b> using frequency F₁(step <b>1400</b>). As described above, the regular event is scheduled and the frequency is decided upon by electronic device <b>200</b> and assistive-listening device <b>300</b> as part of the initialization of the BTLE network connection. Additionally, “using” frequency F₁comprises configuring one or more mechanisms (radios, etc.) in the Bluetooth interface in electronic device <b>200</b> to use frequency F₁when transmitting the first data channel PDU.

0149Electronic device <b>200</b> then, during a corresponding retransmission event (and in electronic device <b>200</b>'s retransmission window), transmits a second data channel PDU with a payload that includes the same data D to assistive-listening device <b>300</b> using frequency F₂(step <b>1402</b>). As described above, in some embodiments, the retransmission of the data occurs automatically, without receiving a request message from assistive-listening device <b>300</b> at electronic device <b>200</b>. In addition, in the described embodiments, frequency F₂is different than frequency F_I. (Although not shown in <figref idref="DRAWINGS">FIG. 14</figref>, electronic device <b>200</b> then proceeds to the next regular event.)

0150<figref idref="DRAWINGS">FIG. 15</figref> presents a flowchart illustrating a process for communicating between electronic device <b>200</b> and assistive-listening device <b>300</b> using an event-based scheme with retransmission events in accordance with the described embodiments. Generally, the process shown in <figref idref="DRAWINGS">FIG. 15</figref> occurs after electronic device <b>200</b> and assistive-listening device <b>300</b> have initialized a BTLE network connection using operations known in the art. Note that initializing the BTLE network connection in the described embodiments comprises configuring a connection interval <b>900</b> (i.e., the timing of regular events), as well as the timing of retransmission events.

0151The process shown in <figref idref="DRAWINGS">FIG. 15</figref> starts when assistive-listening device <b>300</b>, during a regular event (and in assistive-listening device <b>300</b>'s receiving window), receives a first data channel PDU with a payload <b>504</b> that includes data D from electronic device <b>200</b> using frequency F₁(step <b>1500</b>). As described above, the regular event is scheduled and the frequency is decided upon by electronic device <b>200</b> and assistive-listening device <b>300</b> as part of the initialization of the BTLE network connection. Additionally, “using” frequency F₁comprises configuring one or more mechanisms (radios, etc.) in the Bluetooth interface in assistive-listening device <b>300</b> to use frequency F₁when receiving the first data channel PDU.

0152Assistive-listening device <b>300</b> next determines whether the data D in the payload of the first data channel PDU has been received in a correct condition (step <b>1502</b>). More specifically, assistive-listening device <b>300</b> can perform one or more operations to check if the data D transmitted by electronic device <b>200</b> in the payload of the first data channel PDU matches the data D received by assistive-listening device <b>300</b> in the payload of the first data channel PDU. In some embodiments, this means computing a cyclic redundancy check (CRC) value for the first data channel PDU, and comparing the computed CRC value with an CRC value in a field in the first data channel PDU to determine if the data matches. Mismatches in the data D can be due to a number of different influences; however one common influence is interference at the transmission frequency F₁that corrupts the first data channel PDU as it is wirelessly transmitted from electronic device <b>200</b> to assistive-listening device <b>300</b>.

0153If assistive-listening device <b>300</b> did not receive data D in the correct condition during the regular event, assistive-listening device <b>300</b>, during a corresponding retransmission event (and in assistive-listening device <b>300</b>'s receiving window), receives a second data channel PDU with a payload <b>504</b> that includes the same data D from electronic device <b>200</b> using frequency F₂(step <b>1504</b>). As described above, in some embodiments, the retransmission of the data from electronic device <b>200</b> occurs automatically, without receiving a request message from assistive-listening device <b>300</b> at electronic device <b>200</b>. Thus, in these embodiments, electronic device <b>200</b> can always transmit the second data channel PDU with the same data, and assistive-listening device <b>300</b> can simply receive the data when it has a reason to do so. Also, as described above, frequency F₂is different than frequency F₁.

0154In some embodiments, assistive-listening device <b>300</b> sends a third data channel PDU to acknowledge the correct receipt of the data D during either the regular event or the retransmission event. This can comprise sending the third data channel PDU during a sending window for assistive-listening device <b>300</b> during either the regular event or the retransmission event. However, in some embodiments assistive-listening device <b>300</b> does not send the third data channel PDU with the acknowledgement message.

0155If assistive-listening device <b>300</b> received data D in the payload of the first data channel PDU in the correct condition during the regular event, assistive-listening device <b>300</b> has the data D, and hence does not need to receive the second data channel PDU with data D that is transmitted by electronic device <b>200</b> during a corresponding retransmission event. Thus, assistive-listening device <b>300</b> can configure one or more portions of the BTLE interface in a low-power mode during at least the retransmission event (step <b>1506</b>). In the low-power mode, the second data channel PDU transmitted from the electronic device <b>200</b> during the retransmission event is ignored and not received in the assistive-listening device <b>300</b> (step <b>1508</b>). Note that although we describe an embodiment where one or more portions of the BTLE interface are configured in a low-power mode during at least the retransmission event, alternative embodiments leave the BTLE interface in a full power operating state, but otherwise ignore and/or do not receive the second data channel PDU transmitted from the electronic device <b>200</b> during the retransmission event.

0156The foregoing descriptions of embodiments have been presented only for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the embodiments.