Abstract:
Providing an audio broadcast for a TDMA system. During a single time slot, an audio message is broadcast from a base art and received at a number of portable arts. An audio broadcast command is generated by designating the single time slot and then transmitted to the plurality of portable parts. An additional portable part transmits a broadcast origination signal and the audio message to the base part which transmits the audio broadcast command to the portable parts. by assigning a time slot other than the designated time slot to a portable part, the portable part does not broadcast audio messages during the designated time slot. More than three receiving time slots and more than three sending time slots are divided out for the base art that includes the designated time slot. The audio broadcast command is transmitted during at least two of the more than three sending time slots.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to personal telephone systems, that are able to transmit and receive digital signals between fixed sets and fixed stations in a cordless system. More particularly, the present invention relates to audio broadcasts on such cordless telephone systems. 
     Time division multiple access (TDMA) cordless phone systems provide a base unit which is able to provide connections for a plurality of mobile units, such as handsets. Such TDMA systems use time division to provide a plurality of slots, where the base (fixed part (FP)) transmits to an individual (portable part (PP)) mobile unit during a particular slot of time and receives from the individual mobile unit during a particular slot of time. Some TDMA standards may be WDCT, HOME-RF, and Bluetooth. One standard for TDMA systems is the Digital European Cordiess Telecommunications DEC Common interface standard described in ETS 300 175-2 and ETS 300 175-3, published by the European Telecommunication Standards Institute. The DECT standard is also discussed in U.S. Pat. No. 6,078,574 entitled “PROCESS AND APPARATUS FOR ACTION CONTROL IN A TIME SLOT METHOD”, to Boetzel et al. issued Jun. 20, 2000 and U.S. Pat. No. 6,088,338 entitled “METHOD AND SYSTEM FOR THE DETERMINATION OF THE PSCN PARAMETER STARTING FROM THE MFN PARAMETER IN A DECT CORDLESS TELEPHONE SYSTEM” to Rossella et al. issued Jul. 11, 2000, which are incorporated by reference. Generally, the DECT standard may not provide a specification to send a voice message to all mobile units simultaneously as a broadcast. DECT may allow a text broadcast that sends a text message from one unit to all units. 
     It is desirable to provide a broadcast mode that allows a user to transmit an audio broadcast to all units. 
     SUMMARY OF THE INVENTION 
     To achieve the foregoing and other objects and in accordance with the purpose of the present invention an audio broadcast for a time division multiple access system is provided. Generally, an audio message is broadcast from a base part during a single time slot of a time division. The audio message is received by portable parts. The portable parts convert the audio message into sound. 
     These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
         FIG. 1  is a schematic view of a cordless system that uses the invention. 
         FIG. 2  shows a DECT frame structure. 
         FIG. 3  is a flow chart of a method used in an embodiment of the invention. 
         FIG. 4  is a schematic view of a computer that may be used in the base part and the portable parts. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described in detail with reference to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present invention. 
     To facilitate discussion,  FIG. 1  is a schematic view of a cordless system  10 , such as a cordless telephone system that utilizes the invention. The cordless system  10  comprises a base part  11  and a plurality of portable parts  12 ,  14 ,  16 . The base part  11  of the cordless system  10  is connected to a network  18 . The plurality of portable parts  12 ,  14 ,  16  communicate with the base part  11 , which provides communications between the plurality of portable parts  12 ,  14 ,  16  and the network  18 . Although only three portable parts  12 ,  14 ,  16  are illustrated more than three portable parts are possible. For example there may be twelve portable parts communicating to the base part  11 . In this embodiment of the invention, time division multiple access (TDMA) is used to provide communication between each of the plurality of portable parts  12 ,  14 ,  16  and the base part  11 . The base part  11  and the plurality of portable parts  12 ,  14 ,  16  each have a broadcast button  19 . 
       FIG. 2  illustrates a DECT frame structure that uses TDMA and may be used in an embodiment of the invention. A multiframe  20  may contain sixteen frames  22 . Each frame  22  of the multiframe  20  may be 10 ms (milliseconds). Each frame  22  of the multiframe  20  may be split into two sets of twelve full slots  23  of equal size. The slots  23  may be time slots. The base part  11  may transmit to the plurality of portable parts  12 ,  14 ,  16  for the first 5 ms., corresponding to slots  0  to  11  (illustrated as the BP→PP (base part to portable part transmission)). For the second 5 ms., corresponding to slots  12  to  23  (illustrated as the PP→BP (base part to portable part transmission)) the base part may receive from the plurality of portable parts  12 ,  14 ,  16 . A pair of time slots  23 , such as slots  0  and  12 , or  1  and  13  for transmitting and receiving may form a connection (channel). Each portable part  12 ,  14 ,  16  may be assigned a slot  23  from the first 5 ms. and a slot  23  from the second 5 ms., so that each portable part  12 ,  14 ,  16  may be assigned a channel. Since there are twelve channels, the base part  11  may accommodate twelve portable parts. 
     Each time slot  23  may last for 416 μs, which may correspond to 480 bits. Each time slot may be split into a 32 bit synchronization field (sync-field)  25 , a 388 bit D-field  26 , a four bit Z-field  27 , and a 56 bit guard space  28 . The D-field  26  may comprise a 64 bit A-field  30 , a 320 B-field  31 , and a four bit X-field  32 . The A field  30  may comprise an eight bit header (H-field)  35 , a forty bit tail (T-field)  36 , and a 16 bit redundancy (CRC)  37 . The B-field  31  may comprise a 320 bit information field (I-field)  39 . The I-field  39  may be used to carry data, such as part of a digitized audio message. The header  35  may describe the information in the tail  36 . Various commands and command information, such as identification commands, frequency information, slot/frame information, and slot commands may be placed in the tail  36 . The base part  11  and portable parts  12 ,  14 ,  16  receive messages and process the commands in the tail  36 . 
       FIG. 3  is a high level flow chart of a method used in the preferred embodiment of the invention. A broadcast button  19  ( FIG. 1 ) is selected on a unit (step  302 ). The base part  11  and the portable parts  12 ,  14 ,  16  may have broadcast buttons  19 , that allow either the base part  11  or one of the portable parts  12 ,  14 ,  16  to broadcast. The broadcast button  19  may be a button dedicated only to broadcasting or one or more general purpose buttons, which may be pushed in a special sequence for broadcasting. The base part  11  is notified of the selection of the broadcast button  19  (step  304 ). If the broadcast button  19  on the base part  11  is selected, then the selection of the broadcast button  19  is noted by the base part  11 . If the broadcast button  19  on one of the portable parts  12 ,  14 ,  16  is selected, a broadcast command may be placed in the T-field  36  of a message sent to the base part  11 . The base part is then notified of the selection of the broadcast button  19 . In this example, the broadcast button  19  for the first portable part  12  is selected, where the first portable part uses slots  1  and  13 . The base part  11  receives a message during slot  13  with a broadcast command in the T-field  36 , which the base part  11  recognizes as a broadcast request from the first portable part  12 . 
     The base part  11  then transmits a broadcast command (step  306 ). In this example, the base part transmits broadcast command messages during slots  0  and  2 – 11  with a broadcast command in the T-field with a slot designation, for example slot  4 . The remaining plurality of portable parts  14 ,  16  receive the broadcast command messages. The broadcast command in the T-field causes the remaining plurality of portable parts  14 ,  16  to go a receive only mode and become synchronized to receive signals from the designated slot, in this example slot  4  (step  308 ). The first portable part  12  may transmit a plurality of messages with digitized audio information in the I-field  39  (step  312 ). The base part  11  receives the messages from the first portable part  12  at slot  13  and sends broadcast messages with the same digitized audio text during slot  4 , thus rebroadcasting the audio message (step  316 ). Since the remaining plurality of portable parts  14 ,  16  are in a receiving mode and synchronized with slot  4 , all of the remaining plurality of portable parts  14 ,  16  receive the audio message (step  316 ) and access the digital data in the I-field  39  to convert the audio message to sound (step  320 ). The first portable part  12  or the base part  11  may terminate the broadcast mode by having the base part  11  transmit a message that commands the remaining plurality of portable parts  14 ,  16  to synchronize with different slots. 
     If the broadcast button  19  on the base part  11  is selected, then the broadcast audio message is generated at the base part  11 . In such a case, the broadcast message is not received by the base part  11  through one of the slots. 
     In one embodiment of the invention, if a portable part of the remaining plurality of portable parts is busy (i.e. Is being used for a telephone conversation) that portable part will ignore the broadcast message. 
     The network  18  may be a regular telephone system. In the alternative, the network  18  may form a network of base parts. Such a network may form a large network of base parts communicating with portable parts. In such a situation, it may be desirable to provide an audio broadcast to portable parts associated with all of the base parts. In such a case, the base part  11  may also send the audio message to the network  18  of base parts, which broadcast the audio message to the portable parts using the above mentioned method. 
     A representative computer  400  schematically in  FIG. 4  may be placed in the base part  11  and each of the portable parts  12 ,  14 ,  16  where each computer allows the base part  11  and portable parts  12 ,  14 ,  16  to process the frames and commands in the frames. Computer  400  includes a central processing unit (CPU)  402 , which may be a single chip or part of a single chip and which may be coupled bidirectionally with random access memory (RAM)  404  and unidirectionally with read only memory (ROM)  406 . Typically, RAM  404  is used as a “scratch pad” memory and includes programming instructions and data, including distributed objects and their associated code and state, for processes currently operating on CPU  402 . ROM  406  typically includes basic operating instructions, data and objects used by the computer to perform its functions. In addition, a mass storage device  408 , such as a hard disk, CD ROM, magneto-optical (floptical) drive, tape drive or the like, may be coupled bidirectionally with CPU  402 . Mass storage device  408  generally may include additional programming instructions, data and objects that typically are not in active use by the CPU, although the address space may be accessed by the CPU, e.g., for virtual memory or the like. To provide compactness to the base part and portable parts, mass storage may be omitted. Each of the above described computers optionally may include an input/output source  410  that typically includes input media such as a keyboard, pointer devices (e.g., a mouse or stylus) and/or network connections which may form other parts of the base part or portable parts. The CPU and associated commands may be used to provide the inventive base and portable part functions described above. 
     While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and substitute equivalents which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and substitute equivalents as fall within the true spirit and scope of the present invention.