CROSS REFERENCE TO RELATED APPLICATIONSThis application is a continuation of application Ser. No. 09/394,624, filed Jul. 3, 2000, now U.S. Pat. No. 6,282,715 which is a continuation of application Ser. No. 08/776,566, filed Mar. 21, 1997, now U.S. Pat. No. 6,088,051, which is a 371 of PCT/EP95/03089, filed Aug. 1, 1995.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a system and method for telecommunication, specifically interactive telecommunication.
2. Description of the Related Art
Communication between the user apparatus and the server is often not possible as a result of differences in the ways the apparatuses communicate.
OBJECTS AND SUMMARY OF THE INVENTIONThe object of the present invention is to provide means enabling interactive communication along any chosen transmission medium between user apparatuses of various kinds and a server apparatus.
It is also an object of the present invention to provide means performing a minimum number of functions to enable communication between said user apparatus and said server apparatus.
According to the present invention a system is provided, characterized in that said coupling means comprise means for controlling said user apparatus based on information from said server apparatus and for controlling said server apparatus based on information from said user apparatus; and means for creating and for performing communication with said server apparatus and said user apparatus.
Furthermore, said system according to the present invention is characterized in that said coupling means comprise a Set-Top Unit (Set-Top Unit) and a physical medium converter, in that the means for controlling said user apparatus are present in said Set-Top Unit and comprise mainly a program for a dynamic process down-loaded from said server apparatus and stored in a RAM memory and in that means for creating communicating is a program for a static process stored in a ROM memory of the Set-Top Unit.
As a result of the above-mentioned characteristic properties of the system according to the invention, adjustment is achieved on two levels, namely adjustment of said Set-Top Unit to said transmission medium by said physical medium converter and adjustment of the communication between said Set-Top Unit and said server apparatus by programs in said Set-Top Unit originating from said server apparatus.
According to the present invention, a lign-up of Set-Top Units can be developed as commercial products. Also, in order to promote the development of interactive digital audio-video services, Set-Top Unit manufacturers will be left as free as possible to compete in the supply of these Set-Top Units. Therefore, only a minimal set of functionalities is defined in order to be incorporated in a standard. This set can be viewed as a “smart gateway” to interactive digital audio-video services.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention will now be explained in detail with the following description of a preferred embodiment of the invention with reference to the accompanying drawings, in which:
FIG. 1 is a schematic representation of the configuration of elements in the system on both sides of a transmission medium;
FIG. 2 is a schematic representation of the Set-Top Unit shown inFIG. 1; and
FIG. 3 is a schematic representation of the physical medium converter shown in FIG.1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSThe portion of a telecommunication system according to the present invention is shown in FIG.1.
The coupling means are formed by the Set-Top Unit1, together with theconnection channel9 and thephysical medium converter3, the coupling means forming a connection between theuser apparatus10 and thetransmission medium4. Thetransmission medium4 is a connection between the coupling means and theserver apparatus2, theserver apparatus2 having a similar configuration as the Set-Top Unit1, which is emphasized with the mirror-line5 and the representation of thephysical medium converter3 by a dashed line.
The Set-Top Unit1 contains memory space divided mainly into three parts. The “Operating System” is located in the first part6 of the memory space, the “Operating System” controlling communication between the physical apparatus of the Set-Top Unit1 and the programs for static or dynamic processes running in the Set-Top Unit1. It should be noted that an application program interface (API) can run between the Operating System and the programs for static or dynamic processes. In the case of interactive communication, for which the telecommunication system according to the present invention is particularly suited, the Operating System is preferably of the Real Time, Multi Tasking, Object Oriented type and comprises a minimal number of basic instructions. The operating system mainly handles memory management and communication between processes by “message handling”. Thesecond part8 of the memory space contains programs for static processes, which ensure correct functioning of the Set-Top Unit1. Thethird part7 of the memory space contains programs for dynamic processes, which ensure correct communication with theserver apparatus2 chosen by the user.
As theserver apparatus2 has a similar configuration as the Set-Top Unit1, corresponding parts of the memory space of theserver apparatus2 are denoted in a similar way by6′,8′,7′, respectively.
At initiation of the communication between the Set-Top Unit1 and theserver apparatus2 the dynamic processes are sent to the Set-Top Unit1 by theserver apparatus2. Therefore, initiation of the communication can be represented by the following sequence:
- 1. Initiation by the user.
- 2. Relevant static processes become active in the Set-Top Unit1.
- 3. Static processes create a connection with saiduser apparatus10 and with saidserver apparatus2.
- 4. Static process sends relevant information concerning the Set-Top Unit1 in the form of a “Identification Format” to theserver apparatus2. This identification format declares the performance capabilities of the Set-Top Unit1 to theserver apparatus2 at the beginning of the session. These performance capabilities relate to memory size available for dynamic processes, screen driver type or the type of another user apparatus, remote control type, whether additional programs for static processes are available (namely the I/O driver and/or a keyboard driver).
- 5. Static process in theserver apparatus2 assembles programs for dynamic processes suited to the present Set-Top Unit1, where suitability is determined by the information in the “Identification Format”, theserver apparatus2 assuming certain parameters for the present Set-Top Unit1 in the case, when the “Identification Format” contains insufficient information, where these assumed parameters are, for example, fixed as a result of standardization. These parameters comprise preferably a minimum standardized screen driver or other adjustment unit for a user apparatus, a minimum standardized memory size for dynamic processes, a minimum standardized physical user control, being an elementary remote control, and no additional optional programs for static processes. These minimum performance requirements are predetermined, for instance: minimum screen driver in the form of teletext overlay; minimum memory size for dynamic processes, for example, 4M bits; minimum physical user control, preferably a four-“button” cursor plus a select/unselect “button”, where these “buttons” need not be physical buttons.
- 6. Theserver apparatus2 sends the programs for dynamic processes required by the Set-Top Unit1 to the Set-Top Unit1, where these programs are stored in the memory space of the Set-Top Unit1.
- 7. Dynamic processes in the Set-Top Unit1 and dynamic processes in theserver apparatus2 communicate to regulate a stream of data between the Set-Top Unit1 and theserver apparatus2.
 
FIG. 2 is a schematic representation of the configuration of a Set-Top Unit1.
The programs for static processes are present in theROM memory12 and are copied toRAM memory13 when the need arises for such a static process. Programs for static processes resident in the Set-Top Unit1 mainly comprise programs for controlling functioning of an adjustment unit for a user apparatus like a screen driver, a keyboard driver or an I/O port driver, reaction to calls, decoding, handling of remote control, handling of “downloaded” programs and a Resident User Interface (RUI).
In the case, where existing display devices only provide an extremely embedded and elementary mechanism for overlay, a screen driver controlling functioning of the display device may be needed. This process will only remain active as long as a dynamic process does not take over. Similarly, a keyboard driver can control functioning of a terminal. An I/O port driver can, for example, control functioning of a connected game console.
A Resident User Interface process is necessary when the Set-Top Unit1 is switched on. This process is then automatically started, for which it is loaded intoRAM memory13, where this process should be minimal. In the case of a network application, this process merely enables the Set-Top Unit1 to connect to one or a very limited number ofserver apparatuses2 or only to the navigation systems supplied by the network provider (level 1 in U.S. terminology). Once the Set-Top Unit1 gains access to theserver apparatus2 or to the network provider navigation system, the latter downloads the application software at the beginning of the session, including a user interface. An active Resident User Interface process is then put on stand-by and only becomes active again, when the session is terminated for whatever reason. This mechanism enables service providers to tailor their user-interfaces to their needs (and also compete for better user-interfaces). The functionality of the RUI is in any case very simply; it merely enables the user to connect to server apparatuses, which will have their own user-interfaces. It should be noted here, that the Resident User Interface processes could also be used to enable definition of some functions, such as user profile, home profile, etc.
The static process for controlling reaction to calls is activated, when the user has chosen aserver apparatus2 he wishes to be connected to, or when, for example, a first access to a network and a connection to the network is required. The call handler is such a process, which managers all network and protocol tasks (for example, SDH/ATM) in order to establish the connection. If all messages to and from the network are to be handled by this process, it will run as long as the connection to the network (the session with the server apparatus2) is active. Alternatively, when the downloaded software communicates with the network directly (and upper-layer protocol-wise with the server apparatus2), the call handler is terminated at the moment the call is set-up and the connection has been established. Intermediate scenarios are possible, where the call handler process at all times manages the lower-layer protocols and network signaling, whereas the downloaded application software manages the end-to-end protocols. The call handler process depends on the selected network protocols.
In the case of interactive digital telecommunication, for example,MPEG 2 coding can be selected for digital A/V coding, preferably as a standard. If the A/V decoding process is performed by a dedicated piece of hardware, a resident A/V MPEG 2 decoder manager is called for. Microprocessing performance permitting, one could, however, envisage the downloading of the A/V decoding scheme in software.
A program controlling the remote control process is needed to perform at least initial remote control operations. It could also include the process responsible for initial conditional access (including a smart card interface driver). Additionally, some resident “accounting” functions could be performed by this process, monitoring the user's expenditure. In a similar way as the Resident User Interface downloaded application software could take over these functions, in which case this remote control handler would be deactivated, and would only be reactivated when the session is terminated for whatever reason.
A resident program for “download” handling manages processes in thememory space7 for dynamic processes. It is activated when the user has selected aserver apparatus2 to be connected. The application software is then downloaded from theserver apparatus2 into thepart7 of the memory space containing programs for dynamic processes, after which control is handed over to this process. The download process runs as long as a dynamic process is active. When the last dynamic process is completed, control is returned to the Resident User Interface process.
Programs for dynamic processes originating from theserver apparatus2 are stored in theRAM memory13, from where these dynamic processes can run on theprocessor11. Dynamic processes themselves are not resident in the Set-Top Unit1. All dynamic processes originate from various server apparatuses2 (for example, navigation, service providers or content providers). Dynamic processes are loaded in to the Set-Top Unit1 by the download process, which then notifies the operating system of their presence. A downloaded process can then start and carry out its functions by, for instance (and if needed) communicating with the static processes through the operating system. Such dynamic processes are, for example, a tailored user interface, monitor functions, end-to-end protocols, etc. Dynamic processes can use static processes, when necessary. The operating system and the download process are preferably able to accommodate any number of dynamic processes, where the number of downloaded processes simultaneously available will only be limited by memory (RAM13) capacity.
Preferably, it is possible to have more than one dynamic process downloaded, for example, if the user pauses one dynamic process to run another, resuming the first after completion of the second. For example, a user may pause his “video on demand” movie in order to book a flight to where the movie was filmed. The download process is active and ensures that only one process has access to the video/audio decoder hardware.
Preferably, the Set-Top Unit1 contains the following interfaces: network interface (down and return channels); RGB/PAL/SECAM/NTSC interface; analog/digital audio interface; and a UHF interface. As an option an interface can be placed between theMPEG 2 demultiplexer and the video and audio decoders. Also, an I/O (data) interface can be added. The user control/smart card interfaces for remote control may also be provided.
For the network interfaces ATM logical protocols (format and signaling—including call set-up) independently of the physical medium are used, either for the down channel or the return channel, which can be different channels. In this case an ATM adaptation layer (AAL) 5 is needed for signaling. For the transport of the audio-video data an MPEG transport stream can be used. TwoMPEG 2 transport packets could then be contained in eight AAL 5 cells, optimizing overhead. TheMPEG 2 system layer for transport streams provides all necessary means for source clock recovery through time stamps mechanisms. Alternatively, it is possible to use anAAL 1 for transporting theMPEG 2 transport stream by containing oneMPEG 2 transport packet in fourAAL 1 cells. An FEC above thecurrent AAL 1 is optional, as tests have shown, that flagging anMPEG 2 transport packet loss (or even better, a cell loss through the use of the cell sequence numbering available in AAL 1) to theMPEG 2 decoder enables proprietary error concealment techniques to make any picture artifact hardly detectable by any viewer.
The programs for dynamic processes should, however, be downloaded error-free at the beginning of the session between theserver apparatus2 and the Set-Top Unit1. In this case, real-time processing is not required as no isochronicity is required, unlike in A/V streams. It is, therefore, possible to use an ARQ-type and end-to-end recovery protocol. The express transport protocol (XTP), which is less complex than the TCP/IP recovery protocol, can be used to provide such an error-detection mechanism.
The RGB/PAL/SECAM/NTSC interface is intended to be connected to a standard scart interface, which is also the case for analog/digital audio interfaces.
A UHF interface can be used for old televisions, to which current and more modem standard audio/video interfaces cannot be connected.
An I/O (data) interface, which can optionally be added, is a transparent interface (bit stream) allowing connection of other terminals, for example, a game console, to the Set-Top Unit1. In this case, the Set-Top Unit1 is really a “smart gateway” to interactive digital audio/video services.
The schematic representation shown inFIG. 3 shows the physicalmedium converter3.
Theconnection channel9 between the Set-Top Unit1 and thefirst converter21 is usually not of the same kind as thetransmission medium4 between thesecond converter22 and theserver apparatus2. Theconverter3 has a modular configuration in the embodiment shown here, so as to enable simple adjustment to thepresent transmission medium4 by using anotherconverter22 in theconverter3. It is also possible to make theconverter3 suitable forseveral transmission media4,4′ by adding aconverter22′ represented by dashed lines, necessitating the use of aselector24 provided in the connection between theconverters21 and22,22′, between theconnection channels25 and26.
Theconnection channel9 is preferably of one type so that at this side of theconverter3 there is no need for measures like those taken at the other side of theconverter3. To allow for the variety ofpossible transmission media4.
Communication along theconnection channel9 between the physicalmedium converter3 and the Set-Top Unit1 can, for instance, be performed with SDH/Sonnet 155 Mbps. However, the output of the physicalmedium converter3 to the Set-Top Unit1 is subject to some minimum performance requirements, namely, in terms of the Bit Error Rate (BER), regardless of thephysical transmission medium4 used as an access network (coaxial cable, fiber cable, ADSL, etc.). As a result of this mechanism, the Set-Top Unit1 is completely independent of the type ofphysical transmission media4 used as access networks.
The physicalmedium converter3 can be incorporated in the Set-Top Unit1, even though they have been represented by individual elements in FIG.1 and FIG.2. Further, the coupling means formed by the Set-Top Unit1 or by the Set-Top and the physicalmedium converter3 can be incorporated in the user-apparatus10 to form a unit therein.