Abstract:
Integrated Bluetooth (BT) and Wireless Local Area Network (WLAN) transceivers are described. BT signals and WLAN signals can be transmitted simultaneously with one another. Samples from a BT signal sample stream are injected into a WLAN signal sample stream. According to one exemplary embodiment, a simultaneously transmitted BT signal/WLAN signal can be amplified and coupled onto a pin of an integrated circuit device for transmission. If there is no WLAN signal to be transmitted when a BT signal is to be transmitted, then the BT signal can be processed in a BT section of the transceiver, amplified and coupled to the same pin for transmission.

Description:
RELATED APPLICATION 
     This application is related to, and claims priority from, U.S. Provisional Patent Application No. 61/370,895, entitled “Integrated Bluetooth and Wireless LAN Transceivers”, filed on Aug. 5, 2010, the disclosure of which is incorporated here by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to communications systems, devices and methods and, in particular, to integrated Bluetooth and WLAN transceivers. 
     BACKGROUND 
     As technology advances, the options for communications have become more varied. For example, in the last 30 years in the telecommunications industry, personal communications have evolved from a home having a single rotary dial telephone, to a home having multiple telephone, cable and/or fiber optic lines that accommodate both voice and data. Additionally cellular phones and wireless networking technologies have added a mobile element to communications. In terms of wireless networking communications, two of the currently dominant, standardized approaches are specified in the Wireless LAN (WLAN, “Wi-Fi”, 802.11a/b/g/n) standard and the Bluetooth standard. 
     WLAN devices are frequently used, for example, to provide wireless Internet connectivity and operate in two frequency bands, i.e., a low band disposed in the 2.4 GHz Industrial, Scientific and Medical Band (ISM band) and a high band disposed in the 5 GHz range. Bluetooth devices also operate in the 2.4 GHz band and are frequently used, for example, for short range wireless communications, e.g., between a mobile phone and an associated earbud device. 
     Increasingly, WLAN devices and Bluetooth devices operate in proximity to one another and, recently, there has been an interest in providing integrated WLAN/Bluetooth transceivers. This raises various co-existence challenges associated with the different standardized radio interfaces, as well as other challenges associated with, for example, reducing pin and component counts as described in more detail below. 
     SUMMARY 
     Integrated Bluetooth (BT) and Wireless Local Area Network (WLAN) transceivers are described. BT signals and WLAN signals can be transmitted simultaneously with one another. Samples from a BT signal sample stream are injected into a WLAN signal sample stream. According to one exemplary embodiment, a simultaneously transmitted BT signal/WLAN signal can be amplified and coupled onto a pin of an integrated circuit device for transmission. If there is no WLAN signal to be transmitted when a BT signal is to be transmitted, then the BT signal can be processed in a BT section of the transceiver, amplified and coupled to the same pin for transmission and vice versa. 
     According to an exemplary embodiment, a device includes a first air interface transmitter section configured to transmit a first air interface signal, a second air interface transmitter section configured to transmit a second air interface signal, and an interface between the first air interface transmitter section and the second air interface transmitter section, the interface configured to add signal samples associated with the first air interface signal into a signal sample stream associated with said second air interface signal, wherein the first air interface signal and the second air interface signal are transmitted simultaneously via the second air interface transmitter. 
     According to another exemplary embodiment, a method for transmitting signals includes the steps of: generating a sample stream including signal samples associated with a first air interface signal to be transmitted and signal samples associated with a second air interface signal to be transmitted, converting the sample stream to an analog signal, amplifying the analog signal, and transmitting the analog signal to simultaneously transmit the first air interface signal and the second air interface signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate exemplary embodiments, wherein: 
         FIG. 1  illustrates a communication system according to an exemplary embodiment; 
         FIG. 2  illustrates a portion of an exemplary WLAN/BT transceiver on a chip according to an exemplary embodiment; 
         FIG. 3  shows a WLAN transmit processing chain including BT signal sample injection according to an exemplary embodiment; 
         FIG. 4  is a flowchart depicting a method of transmitting BT and WLAN signals simultaneously according to an exemplary embodiment; and 
         FIG. 5  is a flowchart depicting a method of transmitting BT and WLAN signals simultaneously according to another exemplary embodiment. 
     
    
    
     ACRONYM LIST 
     
         
         ADC Analog-To-Digital Converter 
         BT Bluetooth 
         DAC Digital-To-Analog Converter 
         HB High Band 
         LB Low Band 
         LNA Low Noise Amplifier 
         LO Local Oscillator 
         PA Power Amplifier 
         RF Radio Frequency 
         SOC System On Chip 
         WLAN Wireless Local Area Network 
       
    
     DETAILED DESCRIPTION 
     The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. 
     In order to provide some context for this discussion,  FIG. 1  illustrates an exemplary electronic device  100  which is capable of communicating with both WLAN devices, e.g., represented by WLAN access point (AP)  102 , and BT devices, e.g., represented by BT peer  104 . The exemplary electronic device  100  includes a processor  106  which is connected to a memory device  108 , and which controls a combined WLAN/BT transceiver  110 . The WLAN/BT transceiver  110  can be characterized as including an RF front end  112  and a WLAN/BT back end  114  (the latter of which is sometimes also referred to as a system-on-chip (SOC)). 
     As will be described in more detail below, the RF front end  112  is generally responsible, for example, for tasks such as up and down conversion, filtering and amplification of signals which have been received or are to be transmitted by electronic device  100 , while the WLAN/BT back end  114  is generally responsible, for example, for tasks such as modulation/demodulation and coding/decoding of signals to be transmitted or which have been received, respectively. The RF front end  112  and WLAN/BT back end may be integrated into a system on chip (SOC), an integrated circuit (IC) such as an application specific IC (ASIC), or may be provided as two separate chips. The RF front end  112  is connected to one or more antennas  118 , which may take any form, e.g., printed or embedded in a housing of the electronic device  100 , extending or extensible therefrom, etc. 
     A detailed example of a simultaneous BT and WLAN transmission embodiment is illustrated in  FIG. 2 . Considering first the WLAN side digital WLAN signal samples are input to sample rate converter  200 , which converts the rate of those samples in preparation for upsampling at block  202 . The upsampled WLAN signal samples are input to adder  204 , where they can be added to BT signal samples as described below. 
     To determine whether to send the BT signal samples to the WLAN transmit chain (i.e., when simultaneous transmission is occurring) or, alternately, to send the BT signal through the BT transmit chain (i.e., when no WLAN LB signal is to be transmitted simultaneously), logic  206  can be provided. An example is shown in  FIG. 2 , wherein a logic block  206 , e.g., a multiplexer, receives a control signal (simultaneous TX/No simultaneous TX) and switches the BT signal samples either toward the adder  204  or toward the dedicated BT transmit chain, based on receiving the respective control input. The BT transmit chain can be implemented in any desired manner and is not further described here. 
     If, however, the logic block  206  directs the BT samples toward the WLAN transmit chain, then the BT samples are sample rate converted, upsampled and frequency translated in blocks  225 ,  224  and  222 , respectively. One or more of the blocks  206 ,  222 ,  224  and  225  can be considered to be an interface between the WLAN transmitter section and the BT transmitter section, the interface being configured to add signal samples associated with the BT signal into a signal sample stream associated with the WLAN signal. One exemplary mechanism for performing the frequency translation of the BT sample stream and addition to the WLAN sample stream is shown in  FIG. 3 . 
     Therein, an exemplary WLAN signal having a frequency bandwidth  300  of  40  MHz is shown, although it will be appreciated that this bandwidth value is purely illustrative and could be any desired bandwidth. This exemplary WLAN sample stream can be formed as the sum of I and Q signals which are (complex) added together at adder  302  to form a WLAN I+jQ sample of a first number of bits. In the lower part of  FIG. 3 , an exemplary BT signal has a frequency bandwidth  304  of 2 MHz, which value again is purely illustrative. The incoming I and Q signals are digitally multiplied, at multipliers  306  and  308 , respectively, with an offset frequency. The offset frequency can, for example, be selected to be the difference between the BT signal&#39;s hopping frequency and the WLAN channel frequency up to some maximum value, e.g.,  80  MHz. Although illustrated as being digitally mixed with sine and cosine of the offset frequency, since the operation is digital, an oversampled square wave approximation of the sine and cosine functions can be used as inputs to the mixers  306  and  308 , respectively. The outputs are then summed at adder  310  to generate the BT I+jQ sample having a second number of bits and now shifted in the frequency domain as shown by  312 . 
     The BT signal and the WLAN signal are then added together in adder  304  to generate a combined WLAN/BT signal having the WLAN portion centered about an IF frequency and the BT portion shifted outside of the WLAN bandwidth, e.g., as shown in graph  316 . The first number of bits associated with the WLAN sample I+jQ and the second number of bits associated with the BT sample may be different. If so, it may also be desirable to include an amplitude preconditioning function  318  in order to avoid power imbalances between the WLAN portion of the signal and the BT portion of the signal, e.g., to precondition the amplitude of the BT portion of the signal based on the difference (if any) between the number of bits in the two samples. 
     Returning to  FIG. 2 , adder  204  can thus add the in-frequency translated BT signal samples from block  222  with the upsampled WLAN signals from block  602  so that, after digital-to-analog (DAC) conversion  208 , the WLAN signals are centered around the IF frequency and the BT signals are spaced outside the WLAN IF signal. The BT/WLAN simultaneous transmission signal is digitized and upconverted in DAC  208 , which has a high oversampling rate, e.g., sufficient to allow signals having a spacing of approximately 100 MHz to pass, caused by clocking the DAC  208  at a significantly high frequency, e.g., 200 MHz and higher. After digital to analog conversion, the signal is optionally upconverted in mixer  218 . 
     Clock signals are provided by local oscillator  210  and dividers  214  to, for example, the sample rate converter  200  (and  225 ), the upsampler  202  (and  224 ), as well as to the DAC  208  to provide suitable clocking of these elements. Once the simultaneous BT/WLAN signal has been finally upconverted at mixer  218 , it can be passed through other elements  220  in the transmit chain prior to being coupled to an antenna  222  and transmitted. These other elements  220  can include, for example, an interstage matching circuit, a power amplifier (PA), a balun (or a pair of series switched baluns), a switch (e.g., to switch in either the BT transmit chain or the simultaneous BT/WLAN transmit chain to the antenna) and a bandpass filter (BPF). 
     Although described above with respect to WLAN and BT signals, exemplary embodiments can more generally be referred to as simultaneously transmitting signals associated with two different air interfaces, e.g., WLAN and Long Term Evolution (LTE). Thus, according to one exemplary embodiment, a method for transmitting signals includes the steps illustrated in the flowchart of  FIG. 4 . At step  400 , a sample stream is generated including signal samples associated with a first air interface, e.g., WLAN, signal to be transmitted and signal samples associated with a second air interface, e.g., BT, signal to be transmitted. The sample stream is converted to an analog signal at step  402 , and amplified at step  404 . The resulting amplified analog signal is then transmitted at step  406 , to realize a simultaneously transmitted first air interface signal and second air interface signal. 
     According to another embodiment, a method for transmitting signals can include the steps illustrated in the flowchart of  FIG. 5 . Therein a sample stream is generated for a WLAN signal at step  500 . At substantially the same time, a sample stream is generated for a BT signal at step  502 . The BT sample stream is digitally, frequency translated at step  504 , and then the BT sample stream and WLAN sample stream are added together at step  506 . The combined sample stream is converted from digital to analog at step  508  and, optionally, upconverted and amplified at step  510 . The resulting signal is then a concurrent or simultaneous transmission of BT and WLAN information via a single transmit pipe as indicated by step  512 . 
     The above-described exemplary embodiments are intended to be illustrative in all respects, rather than restrictive, of the present invention. Thus the present invention is capable of many variations in detailed implementation that can be derived from the description contained herein by a person skilled in the art. All such variations and modifications are considered to be within the scope and spirit of the present invention as defined by the following claims. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items.