Method for adding additional data rate to legacy physical interface

Abstract

A technique for adding a new information rate to a legacy physical interface of a communication system includes using a rate switching packet that includes a different rate selection start-of-frame delimiter that indicates a newly defined physical interface packet. The rate switching packet uses the same modulation scheme as a base rate packet (e.g., a packet using an information rate defined by a standard communication protocol) and the same preamble mode as the base rate packet. The preamble length of the rate switching packet may be the same as or different from the preamble length of the base rate packet. Embodiments use antenna diversity by selecting an antenna in a rate switching packet and receiving an adjusted rate packet using the selected antenna. An additional rate switch start delimiter may be used to indicate more than one adjusted rate packet, e.g., to support multiple adjusted information rates.

Description

Technical Field

[0001] The present application relates generally to communication systems and, more particularly, to techniques for increasing information rates in communication systems. Background Art

[0002] A communication system that complies with a predetermined communication protocol can be deployed in applications that need to meet increasingly higher information rates (i.e., data rates). Traditional physical interfaces include hardware and software that have been replaced but are difficult to replace due to widespread use. A technology that improves the information rate of traditional physical interfaces includes using mode switching packets with different physical layer headers. Another technology defines new rate bits in existing fields of existing packet formats, which requires new hardware to decrypt or provide seamless rate conversion. Upgrading or completely replacing already widely used hardware may be inconvenient and costly. Therefore, it is desirable to convert traditional physical interfaces with improved technology to support higher information rates. Summary of the invention

[0003] In an embodiment, a method for wireless communication includes sending a basic rate packet, the basic rate packet including a basic rate preamble, a basic rate frame start delimiter, and a basic rate payload. The method includes sending a rate switch packet. The rate switch packet includes a basic rate preamble and a rate switch frame start delimiter. The method includes sending an adjusted rate packet after sending the rate switch packet. The adjusted rate packet includes an adjusted rate preamble, an adjusted rate frame start delimiter, and an adjusted rate payload. The basic rate packet and the rate switch packet are sent at a basic rate, and the adjusted rate packet is sent at an adjusted rate. The adjusted rate is different from the basic rate.

[0004] In an embodiment, a wireless communication system includes a transmitter having a first operating mode and a second operating mode. In the first operating mode, the transmitter is configured to send information at a basic rate, the transmitter is configured to send a basic rate packet, the basic rate packet includes a basic rate preamble, a basic rate frame start delimiter, and a basic rate payload, and the transmitter is configured to send a rate switch packet, the rate switch packet includes a basic rate preamble and a rate switch frame start delimiter. In the second operating mode, the transmitter is configured to send information at an adjusted rate, and the transmitter is configured to send an adjusted rate packet after sending the rate switch packet. The adjusted rate packet includes an adjusted rate preamble, an adjusted rate frame start delimiter, and an adjusted rate payload. The adjusted rate is different from the basic rate.

[0005] In an embodiment, a wireless communication method includes receiving a basic rate packet, the basic rate packet including a basic rate preamble, a basic rate frame start delimiter, and a basic rate payload. The method includes receiving a rate switch packet. The rate switch packet includes a basic rate preamble and a rate switch frame start delimiter. The method includes receiving an adjusted rate packet after receiving the rate switch packet. The adjusted rate packet includes an adjusted rate preamble, an adjusted rate frame start delimiter, and an adjusted rate payload. Information in the basic rate packet and the rate switch packet is received at a basic rate, and information in the adjusted rate packet is received at an adjusted rate. The adjusted rate is different from the basic rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present invention may be better understood, and its numerous objects, features and advantages made apparent to those skilled in the art by referencing the accompanying drawings.

[0007] Figure 1 A functional block diagram of an exemplary wireless communication system is shown.

[0008] Figure 2 Shows Figure 1 Functional block diagram of an exemplary wireless communication transmitter.

[0009] Figure 3 Shows Figure 1 A functional block diagram of an exemplary wireless communication receiver.

[0010] Figure 4 Shown in Figure 1 A functional block diagram of a protocol stack executed on an exemplary wireless communication device.

[0011] Figure 5A Data fields of an exemplary packet for a wireless communication device consistent with at least one embodiment of the present invention are shown.

[0012] Figure 5B An antenna diversity scheme for a wireless communication device consistent with at least one embodiment of the present invention is shown.

[0013] Figure 6 A functional block diagram of an exemplary wireless communication transmitter consistent with at least one embodiment of the present invention is shown.

[0014] Figure 7 A functional block diagram of an exemplary wireless communication receiver consistent with at least one embodiment of the present invention is shown.

[0015] Figure 8 shows at least one embodiment of the present invention. Figure 6 Information and control flows of an exemplary transmitter.

[0016] Fig. 9 shows at least one embodiment of the present invention. Figure 7 Information and control flows for an exemplary receiver.

[0017] Fig.10 shows at least one embodiment of the present invention. Figure 7 Information and control flow of an exemplary receiver of the present invention, the exemplary receiver including a timeout feature.

[0018] Fig.11 shows at least one embodiment of the present invention. Figure 7 Information and control flows for an exemplary receiver that transmits a predetermined number of consecutive adjusted rate packets.

[0019] The use of the same reference numbers in different drawings indicates similar or identical items. DETAILED DESCRIPTION

[0020] A technique for adding a new data rate to a traditional physical interface of a communication system uses a rate switch packet that includes a different rate selection frame start delimiter indicating a newly defined physical interface packet. The rate switch packet uses the same modulation scheme as a basic rate packet (e.g., a packet sent using a modulation scheme and information rate defined by a standard communication protocol) and the same preamble pattern as the basic rate packet. The preamble length of the rate switch packet can be the same or different from the preamble length of the basic rate packet. An embodiment exploits antenna diversity by using the rate switch packet to select an antenna for adjusted rate communication and using the selected antenna to receive the adjusted rate packet. Additional rate switch frame start delimiters can be used to indicate more than one adjusted rate packet, for example, to support multiple adjusted data rates.

[0021] refer to Figure 1In at least one embodiment, the wireless communication system 100 includes a wireless communication device 102 and a wireless communication device 116, wherein the wireless communication device 102 has a transmitter 104, a receiver 106, a control and data processing circuit 108, and a memory 110, and the wireless communication device 116 has a transmitter 118, a receiver 120, a control and data processing circuit 126, and a memory 124. Although the wireless communication device 102 and the wireless communication device 116 are shown as each including only one transmitter, one receiver, and two antennas, in other embodiments of the wireless communication system 100, the wireless communication device 102 or the wireless communication device 116 includes multiple transmitters, receivers, additional antennas, or a single antenna with internal circuit selection or radio frequency switching. The wireless communication system 100 can transmit information modulated using a predetermined wireless communication protocol, for example, data modulated using a wide personal area network (WPAN) protocol (e.g., a protocol based on IEEE 802.15.4) or data modulated using a wide local area network (WLAN) protocol (e.g., IEEE 802.11b / g / n protocol). However, in other embodiments, the wireless communication system 100 may transmit and receive data conforming to other wireless communication protocols.

[0022] Figure 2 An exemplary embodiment of a transmitter 104 is shown, which may be included in Figure 1 In the physical radio device of the wireless communication device 102 or the wireless communication device 116. Figure 2 The control and data processing circuit 108 can perform a variety of functions (e.g., logic, arithmetic, etc.). For example, the data processing circuit 108 executes a program, routine, or algorithm (whether software, firmware, hardware, or a combination thereof) and provides data to the modulator 228, which performs the desired control or data processing tasks consistent with the physical layer of the communication protocol. In at least one embodiment, the transmitter 104 implements the IEEE 802.15.4 communication protocol (e.g., Zigbee with an information rate of 250kbps) using offset quadrature phase shift keying (OQPSK) with direct sequence spread spectrum (DSSS) (i.e., using a pseudo-random bit sequence called an extended sequence). Each bit of the extended sequence is called a chip. In an exemplary embodiment, each half-byte of data (e.g., a value represented by four bits of data) is represented by a 32-bit chip sequence, and the extended code generator 230 provides an extended sequence for use by the modulator 228.

[0023] The modulator 228 provides modulated data to the transmit baseband circuit 232, which, in an embodiment, includes a digital-to-analog converter and an analog programmable gain filter. The transmit baseband circuit 232 provides a baseband (or intermediate frequency (IF)) signal to the mixer 234, which uses a reference or local oscillator (LO) signal provided by the local oscillator 236 to perform a frequency conversion or shifting of the baseband signal. In at least one operating mode of the transmitter 104, the mixer 234 converts the baseband signal centered at DC to the 2.4 GHz frequency band. The pre-driver 238 amplifies the signal generated by the mixer 234 to a level sufficient for the power amplifier 240. The power amplifier 240 further amplifies the signal to provide a higher power signal sufficient to drive the passive network 242 and the antenna 202. The passive network 242 provides impedance matching, filtering, and electrostatic discharge protection.

[0024] Figure 3 An exemplary embodiment of a receiver 106 that can be included in a radio device of the wireless communication device described above is shown. Antenna 202 provides a radio frequency (RF) signal to a passive network 204 that provides impedance matching, filtering, and electrostatic discharge protection. Passive network 204 is coupled to a low noise amplifier (LNA) 206 that amplifies the RF signal without substantially reducing the signal-to-noise ratio and provides the amplified RF signal to mixer 208. Mixer 208 uses a reference or local oscillator (LO) signal provided by local oscillator 210 to perform frequency conversion or shifting of the RF signal. For example, in at least one operating mode of receiver 106, mixer 208 converts the RF signal from a 2.4 GHz band to a baseband frequency centered at DC (i.e., ZIF in a zero intermediate frequency (ZIF) operating mode). In another operating mode, the receiver 106 is configured as a low intermediate frequency (LIF) receiver (ie, in a LIF operating mode), and the mixer 208 converts the RF signal to a low intermediate frequency (eg, 100 to 200 kHz) to avoid the DC offset and 1 / f noise issues of a ZIF receiver.

[0025] The mixer 208 provides a converted output signal as a set of two signals, i.e., an in-phase (I) signal and a quadrature (Q) signal. The I and Q signals are analog time domain signals. In at least one embodiment of the receiver 106, the analog programmable gain amplifier and filter 212 provides amplified and filtered versions of the I and Q signals to an analog-to-digital converter (ADC) 214, which converts these versions of the I and Q signals into digital I and Q signals (i.e., I and Q samples). Exemplary embodiments of the ADC 214 use various signal conversion techniques (e.g., delta-sigma (i.e., sigma-delta) analog-to-digital conversion). The ADC 214 provides the digital I and Q signals to the signal processing circuit 218. In general, the signal processing circuit 218 performs digital signal processing of the digital I and Q signals (e.g., demodulation, frequency conversion (e.g., using the digital mixer 216), filtering (e.g., digital filter 220), or signal correction). In at least one embodiment, signal processing circuitry 218 includes a demodulator 224 that recovers or extracts information from digital I and Q signals (e.g., data signals modulated by a transmitter (not shown) and provided as RF signals to antenna 202). In at least one embodiment, a despreading code generator 226 provides codes used by demodulator 224 to detect symbols in a DSSS chip sequence. In at least one embodiment, one or more circuits of signal processing circuitry 218 convert the digital I and Q signals from a Cartesian representation to a polar representation (i.e., instantaneous phase and instantaneous amplitude) for use by a frequency correction circuit or a phase measurement circuit (not shown).

[0026] The control and data processing circuitry 108 may perform various functions (e.g., logic, arithmetic, etc.). For example, the control and data processing circuitry 108 may use the demodulated data in a program, routine, or algorithm (whether in software, firmware, hardware, or a combination thereof) to perform a desired control or data processing task. In at least one embodiment, the control and data processing circuitry 108, including the memory 110, controls other circuits, subsystems, or systems (not shown). In an embodiment, the control and data processing circuitry 108 implements a data link layer including a state machine, defines state transitions, defines packet formats, performs scheduling, performs radio control, and provides link layer decryption in accordance with at least one wireless communication protocol.

[0027] refer to Figure 1 and Figure 4In an embodiment, the wireless communication device 102 includes a separate integrated circuit for implementing the functions of the controller 302 and the host 304. In some embodiments, the wireless communication device 102 incorporates the functions of the controller 302 and the host 304 into a single integrated circuit device. The controller 302 executes instructions to implement a portion of the wireless communication network protocol stack. For example, the controller 302 implements the physical layer 306, which includes software that interacts with the RF transceiver (e.g., the transmitter and receiver described above). The link layer 314 is directly interfaced to the physical layer 306 to handle the transmission and reception of associated signals. In at least one embodiment, the link layer 314 of the controller 302 communicates with the host 304 via the host interface 316. The host 304 implements the upper layers of the communication protocol stack (e.g., the network layer 318, the transport layer 320, and the application layer 322, which implement the upper layers of the protocol stack). In other embodiments, the layers of the software protocol stack have different distributions between the controller 302 and the host 304, or are implemented entirely using the controller 302. The transmitter 104 and the receiver 106 are exemplary only and may vary depending on the communication protocol implemented by the wireless communication system 100 .

[0028] Reference Figure 1 and Figure 5A In at least one embodiment, the wireless communication device 102 uses the basic rate to send conventional radio packets, such as packets conforming to the IEEE 802.15.4 protocol. The basic rate packet 502 includes a basic rate preamble 504 (e.g., four octets of binary zero (i.e., eight symbols)), a basic rate frame start delimiter 506 (e.g., one octet of "11100101" indicating the end of the synchronization header and the beginning of the packet data), a basic rate physical layer header 508 (e.g., one octet), and a basic rate physical layer service data unit 510 having a variable number of octets. The basic rate physical layer service data unit 510 includes a header and a payload. The receiving wireless communication device uses the basic rate preamble 504 for synchronization. The frame start delimiter 506 indicates the end of the preamble. The basic rate physical layer header 508 includes control information, such as the number of bytes in the physical layer service data unit 510, which can be a maximum value of 127 for a 7-bit length field. The basic rate physical layer service data unit 510 includes a media access control (MAC) packet data unit as a payload. In an embodiment, the wireless communication device 102 uses O-QPSK (i.e., offset quadrature phase shift keying) to transmit the basic rate packet 502. In an exemplary embodiment, four information bits are used to select one of 16 nearly orthogonal pseudo-random noise (PN) sequences to transmit during each data symbol period, thereby spreading the information into 32 chips for transmission at the chip rate.

[0029] During operation in the basic rate configuration, if the wireless communication device 102 determines that the transmission medium has a signal-to-noise ratio (or other indication of the quality of the transmission medium) sufficient to support a higher information rate, the wireless communication device 102 will switch from the basic rate to the adjusted rate configuration to increase the information rate, for example, by abandoning the extension to switch from a 250kbps information rate to a 2Mbps chip rate. In the basic rate configuration, the wireless communication device 102 transmits the information rate change to another wireless communication device by sending a rate switch packet 512. In an embodiment, the rate switch packet 512 includes a basic rate preamble and a rate switch frame start delimiter 514 (e.g., one octet). In an embodiment, the rate switch packet 512 does not include a payload and is smaller than the basic rate packet 502. The small size of the rate switch packet 512 reduces the overhead and inefficiency of the scheme. In other embodiments, the rate switch packet 512 includes a payload field for transmitting control information (e.g., the selection of an antenna for receiving adjusted rate communications). The wireless communication device 102 sends the rate switch packet 512 using the same information rate and modulation scheme as used to send the basic rate packet 502 .

[0030] After sending the rate switch packet 512, the wireless communication device 102 reconfigures itself to operate under the adjusted rate configuration and sends an adjusted rate packet 516. In an embodiment, the adjusted rate packet 516 includes an adjusted rate field: an adjusted rate preamble 520, an adjusted rate frame start delimiter 522, an adjusted rate physical layer header 524, and an adjusted rate physical layer service data unit 526. In general, overhead reduces effective throughput and increases energy used for transmission and reception. Therefore, the adjusted rate field accommodates higher data rates while the increase in overhead is relatively small or minimal (e.g., short preamble and short frame start delimiter). In a bandwidth-constrained regulatory domain (e.g., an orthogonal frequency division multiplexing (OFDM) domain), a physical interface with high bandwidth efficiency may be desired. An exemplary low-cost application uses a simple frequency shift keying (FSK) physical interface. In addition, in some embodiments, the gap between the rate switch packet and the adjusted rate packet is as short as possible, but long enough to enable the wireless communication device to reconfigure the physical interface at each side of the communication link. The wireless communication device 102 continues to use the adjusted rate to send a predetermined number of packets within a predetermined amount of time or indefinitely if conditions permit, as discussed further below. In at least one embodiment, multiple rate switch frame start delimiters are defined to support the selection of an adjusted rate from multiple adjusted rates. The adjusted rate and corresponding operation mode can be entered from a first operation mode at a basic rate or from a second operation mode at another adjusted rate. One or more adjusted information rates can be used to support the selection of an information rate based on a signal-to-noise ratio (SNR), a received signal strength indicator (RSSI), or other quality metrics of the communication link.

[0031] refer to Figure 5B In at least one embodiment, the receiving wireless communication device alternates between at least two antennas (e.g., antenna A0 and antenna A1) during the base rate preamble of the rate switch packet 512. The receiving wireless communication device determines the antenna with the highest probability of successful reception during the base rate preamble based on a quality metric (e.g., SNR, RSSI, error vector magnitude, eye diagram, or other communication quality metric) and selects the antenna to receive the remaining transmissions, including the rate switch frame start delimiter 514, the adjusted rate preamble 520, the adjusted rate frame start delimiter 522, the adjusted rate physical layer header 524, and the adjusted rate physical layer service data unit 526. In this embodiment, since the adjusted rate preamble is not required to determine the antenna with the highest probability of successful reception, a relatively short, adjusted rate preamble is selected. Therefore, the scheme reduces overhead and is relatively efficient, even when antenna diversity is implemented.

[0032] Reference Figure 1 and Figure 6 In at least one embodiment, the adjusted information rate is achieved by sending the information at the chip rate of a conventional system that complies with the IEEE 802.15.4 communication protocol. For example, by eliminating the symbol-to-chip mapping of the information (i.e., eliminating the spread) and instead sending the information at the chip rate (e.g., an O-QPSK chip rate of 2Mcps and an adjusted rate of 2Mbps). Therefore, the transmitter 104 no longer needs to generate a spreading code, and the wireless communication device 102 decouples the spreading code generator 230 from the modulator 228, for example, by deactivating the spreading code generator 230 using the control signal TXSEL. Instead of spreading the four-bit symbol to 32 chip values, the modulator 228 abandons the spreading and provides eight four-bit symbols modulated using O-QPSK. In another embodiment, minimum shift keying (MSK) or other suitable modulation techniques are used instead of O-QPSK. Minimum shift keying of 2Mbps has a modulation bandwidth similar to that of O-QPSK of 2Mcps. To improve the spectral properties of the adjusted rate packets, the MSK symbols are shaped using a Gaussian filter to create a GMSK modulation with a wide symbol time product (BT) of 0.5. The adjusted rate packets use a preamble in the range of 8 bits to 64 bits (e.g., a 16-bit sequence of alternating 1s and 0s). In an embodiment, the adjusted rate packet frame start delimiter is in the range of 16 bits to 32 bits (e.g., 01111100111011000011101101010000), and the adjusted rate packet physical layer header is the same as the physical layer header used by the IEEE 802.15.4-2020 Smart Utility Network (SUN) FSK setting.

[0033] In other embodiments, different basic physical interfaces are used with different adjusted rate physical interfaces. For example, an FSK physical interface is used for the basic rate, and an OFDM physical interface is used for the adjusted rate. OFDM can have a relatively large bandwidth efficiency (i.e., data rate per Hz bandwidth). An exemplary 16-quadrature amplitude modulation (QAM) used by the SUN OFDM physical interface can have about 2.2 bits / Hz, while FSK is about 0.8 bits / Hz. The bandwidth of some sub-GHz communications is constrained, making high efficiency desirable.

[0034] An FSK physical interface (e.g., a SUN FSK physical interface) has a relatively long range to reach many nodes in the network. If the measured link budget allows (e.g., when communicating with a node near the transmitting wireless communication device), a preamble that is the same as the basic rate physical interface and includes a special rate switch frame start delimiter (i.e., a rate switch frame start delimiter that is different from the basic rate frame start delimiter) can be used to send a rate switch packet. If a SUNFSK physical interface is used as the basic rate physical interface, the valid frame start delimiter with an uncoded physical layer service data unit according to the corresponding standard is 1001000001001110. The rate switch frame start delimiter should be different to indicate to the receiver that it should be reconfigured as an OFDM physical interface. An exemplary rate switch frame start delimiter is an inverted version of the basic rate frame start delimiter: 0110111110110001.

[0035] In the exemplary transmitter, when reconfiguring from FSK to OFDM, different modulator paths are used. For example, instead of in-loop modulation as part of a phase-locked loop for generating a radio frequency signal, an IQ modulator is used to generate in-phase and quadrature signals, or a polar modulator is used to generate amplitude and phase signals. The exemplary OFDM transmitter uses a linear power amplifier, while the exemplary FSK transmitter uses a nonlinear power amplifier to achieve high power efficiency. An embodiment of the transmitter 104 has two modulators, a configurable modulator, or a combination thereof (e.g., a portion of the modulator is shared and configurable, while the other portion is dedicated to a predetermined physical interface). In an embodiment including a single transmitter antenna and multiple modulators or transmitter paths, each modulator or transmitter path is selectively enabled and coupled to the transmitter antenna via a radio frequency switch. In an embodiment including multiple transmitter antennas and at least one transmitter path, each modulator or transmitter path is selectively enabled and coupled to the selected transmitter antenna via a radio frequency switch.

[0036] refer to Figure 1 and Figure 7In at least one embodiment, in response to receiving the rate switch packet 512, the wireless communication device 102 configures the receiver 106 to be in an adjusted rate operation mode to receive the information at a higher information rate. In at least one embodiment, the higher information rate is achieved at the chip rate and using the same modulation scheme. For example, the wireless communication device 102 eliminates the chip-to-symbol mapping of the received information (i.e., eliminates despreading) and instead receives the information at the chip rate. Therefore, the receiver 106 no longer needs to generate a despreading code, and the wireless communication device 102 decouples the despreading code generator 226 from the demodulator 224, for example, by deactivating the despreading code generator 226 using the control signal RXSEL. Instead of despreading 32 chip values ​​into 4-bit symbols, the demodulator 224 demodulates 8 4-bit symbols using O-QPSK demodulation and abandons despreading. Embodiments of the receiver 106 have two demodulators, one configurable demodulator, or a combination thereof (e.g., a portion of the demodulator is shared and configurable, while other portions are dedicated to a predetermined physical interface). When receiving using a basic rate physical interface (e.g., receiving a basic rate packet and a rate switching packet), a first demodulator is selected or configured, and when a rate switching packet is received, a second demodulator is selected or configured. In an embodiment including a single receiver antenna and multiple demodulators or receiver paths, each demodulator or receiver path is selectively enabled and coupled to the receiver antenna through a radio frequency switch. In an embodiment including multiple receiver antennas and at least one receiver path, each demodulator or receiver path is selectively enabled and coupled to the selected receiver antenna through a radio frequency switch. In an exemplary embodiment, multiple transmitter paths or modulators are used with multiple receiver paths or demodulators to achieve a basic rate using OQPSK modulation, and an adjusted rate is achieved using two-level Gaussian frequency shift keying (2GFSK) modulation with BT=0.5. Other embodiments use other combinations of modulation schemes.

[0037] refer to Figure 1 , Figure 6 and Figure 8In at least one embodiment, the wireless communication device 102 configures the transmitter 104 to be in a basic rate operating mode (902). For example, the control and data processing circuit 108 enables the spreading code generator 230 to provide a spreading code to the modulator 228, which uses the spreading code to spread the packet of information into a chip value for transmission at the basic rate. The wireless communication device 102 determines whether to select an adjusted rate configuration after configuring the transmitter 104 to be in the basic rate operating mode (904). In an embodiment, the wireless communication device 102 senses channel quality when communicating using one or more packets in the basic rate operating mode. For example, the wireless communication device 102 senses the quality when receiving an acknowledgment or as part of a quality indication embedded in a payload received from the wireless communication device 116 at the basic rate. If the channel quality is sufficient to transmit the adjusted rate packet, the wireless communication device 102 selects the adjusted rate configuration. Otherwise, the wireless communication device 102 remains in the basic rate operating mode.

[0038] If the adjusted rate configuration is not selected, the transmitter 104 sends the next packet at the basic rate (912). For example, the modulator 228 expands the next information packet to a chip value to be sent at the basic rate using O-QPSK modulation. If the adjusted rate configuration is selected (904), the transmitter 104 sends a rate switch packet at the basic rate (906). After sending the rate switch packet, the control and data processing circuit 108 reconfigures the transmitter 104 to be in an adjusted rate operation mode (908). For example, the control and data processing circuit 108 decouples the spreading code generator 230 from the modulator 228 and configures the modulator 228 to abandon spreading. The transmitter 104 then sends an adjusted rate packet at the adjusted rate (910), for example, modulating eight four-bit symbols using O-QPSK and sending these modulated symbols at the chip rate.

[0039] refer to Figure 1 , Figure 7 and Fig. 9In at least one embodiment, the wireless communication device 102 configures the receiver 106 to be in a basic rate mode of operation (1002). For example, the control and data processing circuit 108 enables the despreading code generator 226 to provide a despreading code to the demodulator 224, which uses the despreading code to recover the information symbol from the received chip value. The control and data processing circuit 108 searches the received bits for a basic rate frame start delimiter or a rate switch frame start delimiter (1004). In response to detecting the basic rate frame start delimiter or the rate switch frame start delimiter, the control and data processing circuit 108 determines whether the frame start delimiter is associated with a basic rate packet or a rate switch packet (1006). If the frame start delimiter is not a rate switch frame start delimiter, the receiver 106 recovers the basic rate physical data unit from the packet according to the predetermined communication protocol (1014). If the frame start delimiter indicates that the packet received at the basic rate is a rate switch packet, the control and data processing circuit 108 reconfigures the receiver 106 to be in an adjusted rate operation mode (1008). For example, the control and data processing circuit 108 uses the control signal RXSEL to decouple the despreading code generator 226 from the demodulator 224 and configure the demodulator 224 to recover symbols at the chip rate instead of the conventional information rate. The receiver 106 searches for subsequently received bits until the adjusted frame start delimiter is detected (1010), and in response to detecting the adjusted frame start delimiter, the receiver 106 recovers the adjusted rate physical layer service data unit in the adjusted rate packet (1012).

[0040] In at least one embodiment, receiver 106 starts a timer in response to receiving a rate switch packet. If an adjusted rate preamble or an adjusted rate frame start delimiter is not received within a predetermined time from starting the timer, receiver 106 reverts from the adjusted rate configuration to the basic rate receiver configuration. This prevents receiver 106 from being endlessly configured to an adjusted rate, thereby preventing receiver 106 from losing the ability to recover basic rate packets.

[0041] refer to Figure 1 , Figure 7 and Fig.10In at least one embodiment, the wireless communication device 102 configures the receiver 106 to be in a basic rate mode of operation (1102). The control and data processing circuitry 108 searches the received bits for a basic rate frame start delimiter or a rate switch frame start delimiter (1104). In response to receiving the basic rate frame start delimiter or the rate switch frame start delimiter, the control and data processing circuitry 108 determines whether the frame start delimiter is associated with a basic rate packet or a rate switch packet (1106). If the packet received at the basic rate is not a rate switch packet, the receiver 106 recovers a basic rate physical data unit from the packet (1116). If the frame start delimiter indicates that the packet received at the basic rate is a rate switch packet (1106), the control and data processing circuitry 108 reconfigures the receiver 106 to be in an adjusted rate mode of operation (1108) and starts a timer or counter (1110). The receiver 106 searches for the adjusted frame start delimiter in subsequently received bits (1112). If an adjusted frame start delimiter is not detected, the receiver 106 compares the amount of time that has elapsed since the timer was started to a predetermined time limit to determine whether the predetermined amount of time has expired (1118). If the predetermined time has elapsed without detecting the next adjusted rate packet, the receiver 106 reconfigures itself to be in a basic rate mode of operation to receive basic rate packets (1102). If the predetermined amount of time has not elapsed (1118), the receiver 106 continues to search for received adjusted rate packets (1112). In response to detecting an adjusted rate preamble or an adjusted rate frame start delimiter (1112), the receiver 106 recovers the adjusted rate physical layer service data unit in an adjusted rate packet (1114).

[0042] In at least one embodiment, in response to receiving a predetermined number of consecutive adjusted rate packets, the receiver 106 reverts from the adjusted rate configuration to the basic rate configuration. The first adjusted rate packet carries information indicating the predetermined number of consecutive adjusted rate packets to be received before reverting to the basic rate configuration. For example, after receiving a single rate switch packet, the next received adjusted rate packet carries an indication of the predetermined number of consecutive adjusted rate packets after the rate switch packet. In an embodiment, if the indication corresponds to a predetermined number 1, no adjusted rate switch packets will be restored after the first adjusted rate packet. In an embodiment, if the indication corresponds to a predetermined integer N, N-1 more adjusted rate packets will be received after the first adjusted rate packet. In at least one embodiment, the indication is embedded in the physical layer payload (i.e., physical layer service data unit), for example as part of a MAC data unit. In another embodiment, the indication of the first adjusted rate packet received after the rate switch packet is embedded in the rate switch packet itself, for example appended after the rate switch frame start delimiter or as part of the frame start delimiter. The continuous adjusted rate packets may have a fixed length to allow the receiver to set a timeout after which the receiver will switch back to the basic rate mode of operation. In this embodiment, there is no need to send an indication of the continuous adjusted rate packets after the rate switch packet, because the receiver can determine whether the listed continuous adjusted rate packets have been received since the time when the listed continuous adjusted rate packets should have been received, and can request retransmission of any lost listed continuous adjusted rate packets accordingly. In other embodiments, the indication is embedded in the physical layer header. In an embodiment, the transmitter embeds counting information into each packet and decrements the count associated with each adjusted rate packet sent. The receiver can use this information to determine whether one or more continuous adjusted rate packets have not been received, and can request retransmission of the corresponding packets by reference to the associated number.

[0043] like Figure 1 , Figure 7 and Fig.11As shown, in at least one embodiment, the wireless communication device 102 configures the receiver 106 to be in a basic rate operating mode (1202). The control and data processing circuit 108 searches the received bits for a basic rate frame start delimiter or a rate switch frame start delimiter (1204). In response to receiving the basic rate frame start delimiter or the rate switch frame start delimiter, the control and data processing circuit 108 determines whether the frame start delimiter is associated with a basic rate packet or a rate switch packet (1206). If the packet received at the basic rate is not a rate switch packet, the receiver 106 recovers the basic rate physical data unit from the packet (1214). If the frame start delimiter indicates that the packet received at the basic rate is a rate switch packet, the control and data processing circuit 108 reconfigures the receiver 106 to be in an adjusted rate operating mode (1208). The receiver 106 searches for subsequently received bits until an adjusted frame start delimiter is detected (1210). In response to detecting the adjusted start of frame delimiter, receiver 106 resumes the adjusted rate physical layer service data unit and a predetermined number of remaining consecutive adjusted rate packets to be received (1212). If the predetermined number of remaining consecutive adjusted rate packets to be received exceeds one (1216), receiver 106 searches for the next adjusted start of frame delimiter (1210). If the predetermined number of remaining consecutive adjusted rate packets to be received does not exceed one, receiver 106 reconfigures the receiver to be in the basic rate operating mode (1202). Note that Figures 8 to 11 The information and control flows are exemplary only, and other control sequences may be used.

[0044] In at least one embodiment, rather than using a timer, counter, or continuous adjusted rate packet indicator, receiver 106 performs a channel quality test, such as using a received signal strength indicator or other suitable technique. In response to detecting a degradation in channel quality or a drop in the channel quality level below a predetermined channel quality threshold level, receiver 106 reverts from the adjusted rate operating mode to the basic rate operating mode.

[0045] In at least one embodiment, if the wireless communication device supports rate switching packets, the wireless communication device communicates this capability to another wireless communication device as part of the physical interface capabilities and may include some detailed information about the supported adjusted rates and the expected frame start delimiter for each adjusted rate. The communication may include, but is not limited to, supported modulation parameters, symbol rates, spreading factors, modulation coding schemes, continuous adjusted rate packets, etc.

[0046] In at least one embodiment, the wireless communication system 100 implements a clear channel assessment (CCA) to ensure that the channel is not being used by any other device. Clear channel assessment may occur prior to rate switching packet communication. The rate switching packet and the adjusted rate packet may be treated as a single transmission, and no additional CCA is required between the rate switching packet and the adjusted rate packet. Since no additional CCA is required, the system spends less time on overhead and rate switching efficiency is improved. If the modulation bandwidth of the rate switching physical interface is different from the modulation bandwidth of the adjusted rate physical interface, the receiving bandwidth in which the CCA is performed is set to the larger of the two modulation bandwidths to ensure that the channel is available for both packets.

[0047] Therefore, a technique for achieving higher information rates using a conventional physical interface without expensive hardware modifications has been disclosed. The technique described herein can be deployed in a wireless communication device using a firmware update. The technique does not require detection of a mode switching physical layer header or does not require seamless mode switching, so it can be compatible with conventional hardware and can eliminate the need for hardware updates. Since the preamble of the rate switching packet uses the same mode and modulation as the preamble of the basic rate packet, the radio device can use existing hardware to detect the rate switching packet. Acquiring the rate switching packet may include frequency offset estimation and compensation, automatic gain control, preamble detection, timing recovery, or other processes implemented in conventional systems. Conventional systems only need to check for a new synchronization word or a second frame start delimiter, which can be implemented via a firmware update. In response to detecting a new frame start delimiter (i.e., a rate switching frame start delimiter), the wireless communication device reconfigures the radio device to receive the adjusted rate packet. The technique described herein can be implemented using software executed on a processor (which includes firmware) or by a combination of software and hardware. As described herein, the software can be encoded in at least one tangible (i.e., non-transitory) computer-readable medium. As referred to herein, tangible computer readable media include at least magnetic, optical, or electronic storage media.

[0048] The description of the invention set forth herein is illustrative and is not intended to limit the scope of the invention as set forth in the following claims. For example, although the invention has been described in an embodiment where an IEEE 802.15.4-2020 O-QPSK PHY (e.g., a 250 kbps information rate as used by Zigbee and Thread) interface is configured to support a 2 Mbps information rate, those skilled in the art will appreciate that the teachings herein can be used with other wireless communication protocols to implement other updated information rates. Although the invention has been described in an embodiment where the adjusted rate has an information rate higher than the basic rate, those skilled in the art will appreciate that the teachings herein can be used to implement updated communication rates that differ in other respects due to different transmission parameters (e.g., modulation schemes, extensions, etc.). For example, the basic rate uses O-QPSK and the adjusted rate uses orthogonal frequency division multiplexing (OFDM) technology.

[0049] Unless the context clearly indicates otherwise, the terms "first", "second", "third", etc. used in the claims are intended to distinguish different items in the claims and do not otherwise indicate or imply any temporal, positional, or qualitative order. For example, "a first received signal", "a second received signal" does not indicate or imply that the first received signal occurs before the second received signal in time. Changes and modifications may be made to the embodiments disclosed herein based on the description set forth herein without departing from the scope of the present invention as set forth in the following claims.

Claims

1. A method for wireless communication, the method comprising: sending a basic rate packet, the basic rate packet comprising a basic rate preamble, a basic rate frame start delimiter, and a basic rate payload; Sending a rate switch packet, the rate switch packet including the basic rate preamble and a rate switch frame start delimiter; as well as sending an adjusted rate packet after sending the rate switch packet, the adjusted rate packet including an adjusted rate preamble, an adjusted rate frame start delimiter, and an adjusted rate payload, Wherein, the basic rate packets and the rate switch packets are sent at a basic rate, and the adjusted rate packets are sent at an adjusted rate, the adjusted rate being different from the basic rate.

2. The method according to claim 1, further comprising: After sending the rate switch packet and before sending the adjusted rate packet, a transmitter is reconfigured to transmit at the adjusted rate.

3. The method according to claim 2, wherein: The reconfiguration includes disabling expansion of information.

4. The method according to claim 1, 2 or 3, further comprising: After sending the basic rate packet or the rate switch packet, sensing a channel quality between a transmitter and a receiver; determining whether the channel quality is sufficient for communication at the adjusted rate; as well as The adjusted rate is selected in response to determining that the channel quality is sufficient for communicating at the adjusted rate.

5. The method according to claim 1, 2 or 3, wherein: The rate switch packets have fewer information bits than the basic rate packets.

6. The method according to claim 1, 2 or 3, further comprising: extending information of the basic rate packet before sending the basic rate packet; extending information of the rate switch packet before sending the rate switch packet; as well as The adjusted rate packetized information is sent without expansion.

7. The method according to claim 1, 2 or 3, further comprising: An antenna is selected for adjusted rate communication, the selection using the rate switch packet.

8. The method according to claim 1, 2 or 3, further comprising: sending a second rate switch packet, the second rate switch packet including the adjusted rate preamble or the basic rate preamble and a second rate switch frame start delimiter; as well as sending a second adjusted rate packet after sending the second rate switch packet, the second adjusted rate packet including a second adjusted rate preamble, a second adjusted rate frame start delimiter, and a second adjusted rate payload, wherein the second adjusted rate packets are sent at a second adjusted rate, the second adjusted rate being different from the basic rate and the adjusted rate.

9. The method according to claim 1, 2 or 3, further comprising: The adjusted rate is selected from a plurality of adjusted rates based on a quality metric of the wireless communication.

10. A wireless communication system, comprising: a transmitter having a first mode of operation and a second mode of operation, wherein, in the first operating mode, the transmitter is configured to transmit information at a basic rate, the transmitter is configured to transmit a basic rate packet, the basic rate packet comprising a basic rate preamble, a basic rate frame start delimiter, and a basic rate payload, and the transmitter is configured to transmit a rate switch packet, the rate switch packet comprising a basic rate preamble and a rate switch frame start delimiter, and Wherein, in the second operating mode, the transmitter is configured to send information at an adjusted rate, and the transmitter is configured to send an adjusted rate packet after sending the rate switching packet, the adjusted rate packet including an adjusted rate preamble code, an adjusted rate frame start delimiter and an adjusted rate payload, and the adjusted rate is different from the basic rate.

11. The wireless communication system according to claim 10, wherein: The first wireless communication device comprises: Memory; and A processor configured to execute instructions stored in the memory, wherein the instructions stored in the memory are executable by the processor to cause the processor to reconfigure the transmitter from the first operating mode to the second operating mode after the transmitter sends the rate switching packet.

12. The wireless communication system according to claim 11, wherein: The instructions stored in the memory are further executable by the processor to cause the processor to reconfigure the transmitter from the second operating mode to the first operating mode in response to detecting degradation of a transmission medium used by the wireless communication system.

13. The wireless communication system according to claim 10, 11 or 12, further comprising: A receiver having a third mode of operation and a fourth mode of operation, wherein, in the third operation mode, the receiver is configured to perform information recovery using a basic rate, the receiver is configured to recover a second basic rate packet, the second basic rate packet comprising a second basic rate preamble, a second basic rate frame start delimiter, and a second basic rate payload, and the receiver is configured to receive a second rate switch packet, the second rate switch packet comprising the second basic rate preamble and the second rate switch frame start delimiter, and Wherein, in the fourth operating mode, the receiver is configured to recover information at an adjusted rate, and the receiver is configured to recover a second adjusted rate packet after receiving the second rate switching packet, the second adjusted rate packet including a second adjusted rate preamble, a second adjusted rate frame start delimiter and a second adjusted rate payload.

14. The wireless communication system according to claim 10, 11 or 12, further comprising: a first antenna configured to receive a second rate switching packet at the basic rate; a second antenna configured to receive the second rate switching packet at the basic rate; as well as A receiver configured to generate a plurality of quality metrics during reception of the second rate switch packet using the first antenna and the second antenna, and configured to select the first antenna or the second antenna for receiving communications from another wireless communication device at the adjusted rate based on the plurality of quality metrics.

15. A method for wireless communication, the method comprising: receiving a basic rate packet, the basic rate packet comprising a basic rate preamble, a basic rate frame start delimiter, and a basic rate payload; receiving a rate switch packet, the rate switch packet including the basic rate preamble and a rate switch frame start delimiter; as well as receiving an adjusted rate packet after receiving the rate switch packet, the adjusted rate packet including an adjusted rate preamble, an adjusted rate frame start delimiter, and an adjusted rate payload, Wherein, information in the basic rate packet and the rate switch packet is received at a basic rate, and information in the adjusted rate packet is received at an adjusted rate, the adjusted rate being different from the basic rate.

16. The method according to claim 15, further comprising: A receiver is configured for adjusted rate communications in response to receiving the rate switch packet.

17. The method according to claim 16, wherein: The configuration includes using the chip rate as the information rate.

18. The method according to claim 15, 16 or 17, further comprising: determining whether a next adjusted rate packet is received within a predetermined time limit; as well as The base rate is restored based on the determination.

19. The method of claim 15, 16 or 17, further comprising: An indication that a plurality of adjusted rate packets are to be received consecutively following the rate switch packet is detected.

20. The method according to claim 19, further comprising: The indication is decremented in response to receipt of each of a plurality of adjusted rate packets received successively after the rate switch packet.

21. The method according to claim 20, further comprising: In response to determining based on the indication that at least one of the plurality of adjusted rate packets was not received, a retransmission is requested.

22. The method of claim 15, 16 or 17, further comprising: receiving the rate switch packet using a first antenna and a second antenna; generating a first quality metric corresponding to the first antenna and a second quality metric corresponding to the second antenna; as well as The first antenna or the second antenna is selected based on the first quality metric and the second quality metric for receiving communications at the adjusted rate.

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