Abstract:
A package device has one integrated circuit in a cavity in a package substrate and electrically coupled to one side of the package substrate. A second integrated circuit is mounted on another side of the package device and electrically coupled to that side as well. A third integrated circuit or more may be mounted on the second integrated circuit. Pads useful for testing are present on both sides of the package substrate. The integrated circuits may be tested before final encapsulation to reduce the risk of providing completed packages with non-functional integrated circuits therein.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to communicating conversational data signals between terminals over a radio link.  
       BACKGROUND OF THE INVENTION  
       [0002]     More particularly, the invention relates to communicating conversational data signals between terminals over a radio link capable of full-duplex transmission of conversational data packets. One example of this type of radio link is represented by the Bluetooth standards of the European Telecommunications Standards Institute (‘ETSI’). Bluetooth is a technology that uses radio frequency (RF) transceivers to provide point-to-multipoint wireless connectivity within a personal space. Bluetooth was designed for both voice and data communication at low per-unit costs while consuming little power to achieve the cost and power goals, Bluetooth limits connectivity to a sphere of about 10 meters (more power hunger versions can stretch the effective range up to 100 meters) while providing a maximum data rate of 723 kbps. The communications may be used in wireless Personal Area Networks (‘PAN’s), to connect devices such as a portable telephone, an ear-phone/microphone head-set, a personal digital assistant, a computer, a printer and so on, for example.  
         [0003]     Certain of these applications involve conversational communication, that is to say where data can be sent discontinuously from either one of two terminals to the other and may be unidirectional at a given moment or bidirectional. A typical example of conversational communication to which the present invention is applicable, without being limited thereto, is audio communication, in particular vocal conversation.  
         [0004]     The present invention is particularly applicable to communication of conversational data signals of the above type in which the conversational data packets are transmitted in alternate directions within a pair of time slots, the communication comprising relatively short time periods each comprising a set of said time slots, as in Bluetooth transmissions. Patent specifications WO0241606 and WO0205593 describe communication systems of this general kind.  
         [0005]     Cellular telephone systems, such as the Global Systems for Mobile communication (‘GSM’) system, the Digital Cellular Systems (‘DCS’) and the ‘third generation’ systems, such as Wide-band Code Division Multiple Access (‘W-CDMA’), also enable conversational communications but the signals between two cellular telephone pass through a base station and these systems are not adapted to wireless Local Area Networks (‘LAN’s) nor PANs. The conversational data packets are not transmitted in alternate directions within sets of pairs of time slots for GSM, DCS, WCDMA FDD the signal directions use 2 different frequencies, one for uplink &amp; one for downlink, for WCDM TDD, uplink &amp; downlink signals use the same frequency but time slots are not managed in pairs of time slots of the same length.  
         [0006]     In fact there is demand for associating cellular telephones with wireless PAN or LAN links to associated devices, such as head-sets or processing devices so that communication occurs over the cellular telephone system with remote cellular telephones and is relayed to the associated head-sets or processing devices over the wireless PAN or LAN link.  
         [0007]     Current consumption is a stringent problem in any portable application. Implementing Bluetooth or a similar communication system requires current consumption and decreases the battery life time, which is especially critical in cellular telephone applications. A second consequence is that the power management unit must be designed so that it has a sufficient maximum current capability (up to 50 mA to 100 mA additional peak current due to Bluetooth, for example) this increases the power management die size.  
         [0008]     Another problem that can arise is that, the greater the power transmitted over the wireless PAN or LAN link, the more risk there is of interference with other wireless PAN or LAN (like 802.11b LAN) or with cellular telephone transmissions and reception. Also, it makes sense to limit the conversational data packets only in order to allocate more bandwidth to other terminals of the same PAN, thereby improving the Quality of Service.  
         [0009]     The present invention addresses these and other problems.  
         [0010]     Patent Specification U.S. Pat. No. 6,269,331 describes communication over a GSM link in which ‘comfort noise’ is generated, that is to say a white noise (the comfort noise is intended to give to the listener the feeling that the call is still connected, while absolute silence in the receiver gives the user the feeling that the call has been dropped); in the system described in that patent specification, audio activity is detected and blocks a comfort noise parameters are transmitted, instead of transmitting the comfort noise itself. This patent specification does not describe a Bluetooth or similar link capable of full-duplex transmission of conversational data packets between two terminals in alternate directions within a set shorter than the phoneme time of pairs of time slots and does not minimize the current consumption of the wireless terminals.  
         [0011]     Patent specification EP 1 261 176 and WO 01 08426 and ETSI publication number XP-002098616 “Discontinuous Transmission (DTX) for Enhanced Full Rate (EFR) speech traffic channels” describe various ways of using voice activity detection to enhance user comfort or to reduce occupation or to make fuller use of the occupation of transmission channels. However, the technologies described do not address all the above problems of a conversational communication, especially not in the context of a communication link like Bluetooth.  
       SUMMARY OF THE INVENTION  
       [0012]     The present invention provides a method of, and a terminal for, communicating conversational data signals as described in the accompanying claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a schematic diagram of a communication system in accordance with one embodiment of the invention based on the Bluetooth standard, given by way of example,  
         [0014]      FIG. 2  is a diagram of HV2 signals transmitted and received in a known PAN/LAN communication system using the Bluetooth standard,  
         [0015]      FIG. 3  is a diagram of signals transmitted and received in a know cellular telephone communication system using the GSM standard,  
         [0016]      FIG. 4  is a diagram of signals transmitted and received in a PAN/LAN communication system in accordance with the embodiment of the invention illustrated in  FIG. 1  based on the Bluetooth standard,  
         [0017]      FIG. 5  is a block schematic diagram of a Bluetooth terminal in accordance with an embodiment of the invention for use in the system of  FIG. 1 , given by way of example, and  
         [0018]      FIG. 6  is a schematic diagram of a communication system in accordance with another embodiment of the invention including a cellular telephone link and a link based on the Bluetooth standard, given by way of example, 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     The general architecture of a system incorporating one embodiment of the present invention is shown in  FIG. 1  and includes Bluetooth user terminals A and B comprising respective head-sets which include microphones  1  and  2  and earphones such as  3  and  4  respectively. The terminals A and B are in radio communication with Bluetooth access points  5  and  6  respectively, the communication between the Bluetooth access points  5  and  6  being completed by a network  7 , which may include wired and/or wireless links. Each of the terminals are transceivers, that is to say that each of them includes both radio receiver and transmitter capability for the Bluetooth link. The protocol for communication according to the present Bluetooth standards is illustrated in  FIG. 2  by way of example. Data signals are transmitted between the terminals A and B over Bluetooth radio links with full-duplex transmissions. The data packets are transmitted in alternate directions within pairs of time slots such as T 1  to T 16 , a basic phoneme period of the communication comprising a set of 16 pairs of time slots each of length 0.625 mS. The phoneme time is an audio time interval that is just too short to be distinguished by a listening user.  
         [0020]     In conversational communication such as voice conversation, when A is talking to B then, after at most a short period of full duplex, the user B usually stops speaking and listens to A. The device A must transmit audio data, in particular voice data, and the device B must receive these audio data but there is in fact no need during unidirectional transmissions for A to enable its Bluetooth data receiver capability nor for B to enable its Bluetooth data transmitter capability in the B→A time slots.  
         [0021]     For asymmetric A to B data flow (unidirectional data flow streams from A to B), it is usually required that the devise B acknowledges the received packets from A thanks to Null packets; by this means, the A Bluetooth device knows if it can transmit a new packet or if it has to repeat the previous one. In a speech Bluetooth link, however, voice packets are not acknowledged because they are not repeated. Accordingly, it is possible to switch off the B receiver and the A transmitter in the B→A time slots (and vice versa). The following scheme explains this when the headset owner is talking (the headset being the A device)  
                                                         Voice Activity   Voice Activity           Detection   Detection       A   B   Actions for the next 16 time slots                                Voice   Voice   A: Tx + Rx   Full duplex               B: Tx + Rx       No Voice   Voice   A: Rx   Half duplex B to A               B: Tx + local               comfort noise if               headset       Voice   No Voice   A: Tx + local   Half duplex A to B               comfort noise if               headset               B: Rx                  
 
         [0022]     For this purpose, both Bluetooth devices A and B integrate a Voice Activity Detector that detects if the local Bluetooth device user is talking. The voice activity detection is synchronized between the two Bluetooth devices A and B by sending from each of the terminals A and B to the other one, during each of the phoneme periods, a conversational activity signal indicative of the detected local conversational activity at the corresponding local terminal. When voice activity is detected at only one of the terminals, the Bluetooth link (which has a full-duplex audio link capability) is implemented as a half-duplex voice Bluetooth link, starting from the next phoneme period and until voice activity is detected again at the other, silent terminal. The Bluetooth voice flow is controlled by a control mechanism responsive to the conversational activity signal that synchronizes the transmission/reception control of the two terminals A and B by transmitting and receiving periodically, once during each phoneme period, in the same time slot pair, the status of the transmitting terminal. In this way, when there is no voice activity at one of the terminals A or B, no power is transmitted for the time slot pairs within the next phoneme time, reducing the risk of collisions and interference, also the current consumption is reduced by the non-functioning transmit elements at one terminal and receive elements at the other.  
         [0023]     A Voice Activity Detector is included in a GSM telephone and  FIG. 3  shows how a Silence Insertion Descriptor (‘SID’) packet  8  is inserted in a GSM frame. The GSM frame comprises a transmit channel Tx and a receive channel Rx, the SID packet being included in the receiver channel Rx to avoid having to transmit a white noise comfort signal and hence to reduce coder/decoder (‘CODEC’) calculations. Even when there is no voice activity at one of the telephones, the payload is not reduced since the transmit and receive packets are of fixed length, no reduction in the bandwidth used is obtained, nor reduction in collisions or interference, no reduction in current consumption of the radio transceivers is obtained either, since each telephone maintains transmit and receive capability during the whole frame.  
         [0024]      FIG. 4  shows the method of this embodiment of the present invention as applied to Bluetooth communication when A is talking and B is listening after the voice activity signal has been received so as to synchronize the control of the terminals A and B, the Bluetooth audio stream goes from A to B. The Bluetooth channel from B to A is not needed and is not used. The receiver elements of the A device are shut-down. The A device locally generated a comfort noise from a locally generated white noise signal so that the user of A does not feel that the communication link is lost when the terminal A does not receive a voice signal from B. The B microphone and associated transmit elements are shut-down.  
         [0025]     The audio link is controlled by means of a data line (RFCOMM logical link, for example) so that each unit knows what part of its own transceiver must be turned on. The voice activity detector is enabled ever 32*Ts=20 ms (Ts=625 μs, being the Bluetooth time slot). This sampling rate of the audio channel activity is the phoneme period. In this embodiment of the present invention, the voice activity signal is transmitted only by the terminal whose transmitter is active, as described above and the absence of a voice activity signal at the receiving unit is interpreted as a negative (‘No Voice’) activity signal, however, in another embodiment of the present invention as shown in  FIG. 4 , the inactive transmitter is re-activated during one slot in every phoneme period (20 mS) to transmit a negative (‘No Voice’) voice activity signal. During half-duplex transmission from A to B, as shown in  FIG. 4 , the transmitter of the terminal A is activated to transmit and the receiver of the terminal B is activated to receive in the first slot of each pair T 1  to T 15 . The receiver of the terminal A and the transmitter of the terminal B are deactivated, so that no signals are exchanged during the second slots of each pair T 1  to T 15 . During the last pair of time slots T 16 , the voice activity signal or signals are transmitted and used to control the activation/deactivation of the transmitters and receivers during the following phoneme period.  
         [0026]     There are three kinds of Bluetooth wireless audio links (as described in the Bluetooth 1.1 standard): 
        HV1 link (high power, high quality)     HV2 link (mid power, mid quality)     HV3 link (low power, low quality)        
 
         [0030]     When the embodiment of the present invention shown in  FIG. 4  is applied to an HV2 or HV3 Bluetooth link, the HV2 or HV3 audio link is controlled by an Asynchronous-Connection-less Link (ACL). VAD status are transmitted using this ACL. Ideally they are transmitted with DM1 (as described in the Bluetooth 1.1 standard) packets, which are reliable packets thanks to the inclusion of correction bits. The payload may be as short as 60 bits (5 bytes payload header, VAD command, VAD result-CRC16 encoded with a 2/3 coding rate). When the talking Bluetooth device reads the VAD status of the listener Bluetooth device, it knows if it had to switch to receive mode, switch to full duplex mode (a relatively unusual usage case), or hold in transmit mode. As a consequence, this ACL link is used to control the audio flow.  
         [0031]     When the embodiment of the present invention shown in  FIG. 4  is applied to an HV1 Bluetooth link, once again the HV1 audio link is controlled with an ACL link that is managed by the upper stack layers. However there are no Bluetooth time slots free to transmit this audio flow control information because an HV1 link requires the whole Bluetooth channel Bluetooth bandwidth, so the audio flow control information is transmitted using a DV packet (as defined in Bluetooth 1.1 specification) which merges audio and control data in the same packet (DV packet). The audio field is not protected with parity bits, as a consequence, there are potential error in this audio packet. However, upwards digital processing (interpolation) can minimize the audio effects of those errors.  
         [0032]      FIG. 5  shows a Bluetooth terminal for use in the system of  FIG. 1 , comprising a receiver  11  connected to receive Bluetooth signals from an antenna and supply audio signals to headphones  12  and a transmitter  13  connected to receive transmit audio signals from a microphone  14  and transmitting Bluetooth signals through the antenna. A voice activity detector  15  detects the audio signals from the microphone  14  in each phoneme period and provides a detector signal to the transmitter  13 , which transmits a corresponding local voice activity signal over a ACL Bluetooth link to the remote Bluetooth terminal with which the local terminal is in communication. The receiver  11  also detects any remote voice activity signals receive over the ACL link from the remote terminal. A controller  16  responds to both the local voice activity signals and the remote voice activity signals and controls a power supply  17  to the receiver  11  and a power supply  18  to the transmitter  13 .  
         [0033]     The controller  16  responds to conversational activity occurring at a first one of the terminals (A, B) and not occurring at the second one of the terminals (B, A) by controlling the receiver  11  and transmitter  13  to communicate by half-duplex transmission of the audio packet. During the half-duplex transmission the controller  16  at least partially deactivates either the reception means in the absence of remote conversational activity or said transmission means in the absence of local conversational activity so as to reduce power consumption. The deactivation may consist of cutting off the power supply to at least part of the receiver or the transmitter. The receiver is preferably reactivated at least once per phoneme period to check for reception of any remote voice activity signals over the ACL link from the remote terminal.  
         [0034]     The present invention is applicable to communication between two simple Bluetooth terminals A and B through Bluetooth access points  5  and  6  and a network  7 , as in the embodiment of  FIG. 1 . Concerning wired networks, there are a lot of different flow control standards depending on the physical link and logical communication link types. For example, L1/N5/R2, sea &amp; satellite standards, TCP/IP offer audio flow control facilities to reduce the needed bandwidth. As they mostly implement VAD (because of echo cancellation necessary implementation) facilities, they are compatible to work with the idea which is detailed here.  
         [0035]     However, the invention is also applicable in a situation as shown in  FIG. 5  where at least the terminal B communicates with a third terminal C over a further communication link, the terminal B signalling a conversational activity signal indicative of conversational include cellular telephone modules and the terminal B also includes a Bluetooth module of the kind described with reference to  FIG. 1 .  
         [0036]     The mobile phone already includes a VAD module. It avoids transmitting silence frames through the cell-phone network during pauses or when someone else is talking. In the preferred embodiment of the invention, the silence detection is based on cumulated sound energy detection. The silence control is managed between the remote and local cell-phones using an information update through a data channel. In another embodiment of the invention, silence data packets are compressed and signalled using a “SID” packet  8 , containing the silence duration information, as described with reference to  FIG. 3 .  
         [0037]     In these embodiments of the invention, the mobile phone VAD and the Bluetooth wireless headset VAD are synchronized (using a VAD state information transmitted through an ACL data link) in order to determine which device is producing silence and which on is producing voice. The Local device B acts as an audio gateway between the Remote device and the Local Bluetooth device.  
         [0038]     In full-duplex mode, each of the devices is emitting and receiving audio. There is no network optimization. This mode is unusual (because it assumes that each user is speaking without listening to the other one), except that it can happen in half-duplex modes transition (when transmission switches from C torwards B to B towards C).  
         [0039]     When C is talking to A, then after a short period of full duplex, the user A stops speaking and listens. The remote terminal C transmits audio data over the cellular telephone link and the local terminal B receives this audio data. The local terminal B transmits audio data over the Bluetooth link and the Bluetooth terminal A receives this audio data. There is then no need for B to enable its Bluetooth receiver in the A to B time slots and it is deactivated in response to the absence of detection of remote conversational activity at the terminal A from the conversational activity signals received at B over the Bluetooth link. Equally, there is no need for A to enable its transmitter in the A to B time slot and it is deactivated in response to the absence of detection of local conversational activity at the terminal A.  
         [0040]     Conversely, when A is talking to C, then after a short period of full duplex, the user C stops speaking and listens. There is no need for A to enable its Bluetooth receiver in the B to A time slot and it is deactivated in response to the absence of detection of remote conversational activity at the terminal C from the conversational activity signals received at A over the Bluetooth link. Equally, there is no need for B to enable its transmitter in the B to A time slot and it is deactivated in response to the absence of detection of remote conversational activity at the terminal C from the conversational activity signals received at B over the cellular telephone link.  
         [0041]     It will be appreciated that when the communication occurs between terminals all using the same communication standards (the Bluetooth standards, for example), the same activity procedure is used in synchronization between all the terminals. However, in a case such as that described with reference to  FIG. 5 , where communication over different links occurs using different communication standards (cellular telephone standards for the link between B a C and Bluetooth standards for the link between A and B, for example), the different activity procedures are used and the voice activity signal received in one standard is used to generate the voice activity signal to be transmitted in the other standard to obtain the synchronization between all the terminals.