KR20010086242A - Interactive communication system comprising users connected in groups - Google Patents

Abstract

The present invention relates to a communication system comprising a transmission medium, a user connected in groups to the transmission medium via a convergence point, and a main station designed to receive data transmitted via the transmission medium by the user. Access to the transmission medium is restricted to the same group and one of the users at any given moment. According to the invention, the main station comprises means for assigning users access rights to the transmission medium in view of their membership of the user group.

Description

Interactive communication system comprising users connected in groups}

Problems that arise with this type of system include: That is, the convergence point is provided with a transmission means on a transmission medium having a predetermined capacity, so that access to the transmission means at any given moment is restricted to one user and the same group.

For example, technical report TR 101 201 V1.1.1, published in October 1997 by ETSI, describes an interactive SMATV distribution system. In such a system, a group of users share the same antenna with the same transmitter to send a request to the main station of the communication system. Since a transmitter can transmit only one carrier at a given moment, this means that only one user can transmit at a given moment.

Thus, the handling means need to handle the users of the same group to access the transmission medium.

The solution proposed in the above document is shown schematically in FIG. It is constructed by combining the satellite transmission network 1 and the cable network 2. The convergence point 3 is formed by a satellite antenna 4 connected to an interactive satellite terminal 5 which in turn is connected to the central station 6 of the cable network 2. The central station 6 of the cable network 2 is the cable network head according to the recommended ETS 300 800 of ETSI. This serves the end user 7 and provides the satellite transmission network 1 to the interface. This is seen as a single user by the satellite transmission network, and the end user remains unknown to the satellite transmission network.

This solution involves the following problems. In other words, the central station 6 is a cable network head according to the recommended ETS 300 800. Thus this involves relatively expensive equipment. The cost of this equipment is shared among the users of the network 2. This solution is therefore financially viable only if the network 2 contains a sufficiently large number of users.

The present invention relates to a communication system comprising a communication medium between a main station and at least one convergence point for serving a group of users, the convergence point having some transmission capacity on the transmission medium.

The present invention also relates to a user terminal and a main station designed for use in such a system.

In particular, the present invention is applied to a SMATV (Satellite Master Antenna Television) system.

1 shows a system described in the prior art.

2 and 3 illustrate a communication system according to the invention.

4 illustrates the format of a physical address of a user terminal in accordance with the present invention.

5 illustrates the format of a connection message sent by a user terminal to a main station.

6 illustrates a method for allocating a reservation on a transmission medium by a main station in accordance with the present invention.

It is an object of the present invention to provide a cheap and efficient solution for a small group of users. This object is achieved with a system, a main station and a user terminal as claimed in claims 1, 5 and 7 of the present patent application.

The main station controls the path between the convergence point and the user in the communication system according to the invention. This main station assigns a reservation directly to the transmission medium, taking into account the fact that access to the transmission medium is restricted for the same group of users. For example, in the case of an interactive satellite transmission system, the main station assigns a user a talk time interval on a carrier, while ensuring that the same time interval on another carrier is not assigned to the same user group and one other user.

This solution is financially advantageous for the following reasons. That is, the processing of the reservation is shifted to the main station of the communication system so that the management device for such a reservation is no longer needed at the level of convergence point, and from an industrial perspective, the specialization, standard used in a relatively small amount. The production and development of non-medium media is very expensive, and is therefore not specialized in the present invention and is advantageous in that non-standard media can also be used.

In a first embodiment of the invention, the main station is provided with a table which can be manually programmed by the administrator of the communication system, in order to contain the configuration of the communication system, in particular the membership of the users of the user group.

In another embodiment of the present invention, a user of a user group is provided with an identifier for identifying a group to which the user belongs and the user, respectively, and when the user establishes a connection with a communication system, transmitting the identifier to a main station. Configure the transmission means for.

For example, this identifier is formed by the physical address (MAC address) of the terminal formed by the first portion identifying the convergence point and the second portion identifying the terminal. When they make a connection with the system, this physical address is sent in the address field of the connection-establishment message issued by the user.

This solution enables automatic learning processing of the main station based on the base address of the user connecting to the communication system. Thus, no manual configuration operation is required in this case.

The invention also relates to a reservation assignment method as defined in claim 9 and an identification method for a user as defined in claim 10.

The invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, given by way of non-limiting embodiment.

2 shows a communication system according to the invention. The system comprises two transmission media 9 and 10. Transfer medium 9 is a distribution medium that may enable the main station (11) is distributed to the user data T _{i (i} = 0,1,2,3,4). The transmission medium 10 comprises a return path that may enable the user T _i sends a request to the main station (11). The main station 11 is provided with an access point 14 for the transmission medium 10. User T _i (i = 1,2,3,4) is part of user group 15 connected to transmission medium 10 via convergence point 16. User T ₀ is an individual user. He connects to the transmission medium using a personal access point 17.

The present invention relates to the type of all communication systems shown in FIG. 2, where the convergence point 16 has a transmission capacity beyond the limited transmission medium 10, and at any given moment, access to the transmission medium 10. Is restricted for the same group and one user. For example, transmission medium 10 is formed by a radio link or a satellite link.

According to the present invention, the main station 11 is assigned to the user T _i reservations on the transmission medium for, depending on their membership of a group of users. In order to achieve this in the preferred embodiment of the present invention, each user is given an identifier that identifies the group and user to which he belongs. This identifier is then transmitted by the user to the main station when connecting with the transmission system.

For example, this identifier is formed by the physical address T _i of the terminal sent in each connection request sent by the terminal to the main station 11. A particular physical address format is formed of at least two parts, a portion where the physical address identifies a point of convergence and another portion that identifies a terminal.

In the first embodiment, all addresses of the terminal are formed in succession of the first address portion A1 stored at the convergence point or the access point of the terminal and the second address portion A2 stored at the terminal.

In a second embodiment, two unique physical addresses may be applied to the terminal depending on the mode of connection (individually or collectively) to the transmission medium. To accomplish this, the physical address portion A2 and the completed physical address A3 are stored at the terminal. If the terminal is connected in a separate mode, the terminal is assigned a physical address (A3) that is stored completely in the terminal. If the terminal is connected in a collective mode, the physical address formed by concatenating the physical address portion stored at terminal A2 and the physical address portion stored at convergence point A1 together is assigned to the terminal. The individual or collective mode of the terminal's connection (hence the address (A3) or the combined (A1 and A2) to be used) is defined at the time of installation of the terminal and indicated by the state variable (S) stored in the terminal. .

The realization of this second mode allows a group of terminals to have more addresses available.

Upon receiving the connection request, the main station 11 registers the physical address of the terminal connected to the table. The main station 11 traverses this table to assign a reservation to a terminal of the communication system to determine the membership of the associated terminal of the group of terminals.

3 shows an example of an interactive SMATV distribution system according to the present invention.

In such a system, the main station 11, the allocation of the control information and data to a user terminal T _i via the satellite (20). This user T _i transmits data and makes a request to the main station 11 using this same satellite 20.

The following description will exclusively relate to this principle of operation of the interactive satellite transmission system necessary to understand the present invention. For example, a more detailed description can be found in TR 101 201 V1.1.1 of Technical Report ETSI.

To communicate with this main station, the terminal of the interactive satellite transmission system accesses the transmission medium with an access mechanism, for example, a TDMA (time division multiple access) mechanism combined with a frequency division FDMA (frequency division multiple access).

Each carrier is subdivided into time intervals with different access modes associated for this purpose. In particular, the following is used.

A time interval in which all terminals have free access and access to contention mode, with the risk of collision (used to resolve any conflicts in which traditional conflict-resolution algorithms may occur). In particular, this dispute time interval is used by the terminal to connect with the communication system.

A time interval dynamically granted by the main station 11 upon request from the terminal and accessible by reservation. For example, this request may be sent at disputed time intervals, or follow payload data at time intervals already granted by the main station.

When a terminal is connected to a transmission medium by a transmitter and an aggregation antenna, the following problem occurs. This transmitter can transmit and receive only one carrier at any given moment. Thus, the main station should not grant the same group and one user the same time interval on different carriers.

To solve this problem, a specific address format is used for the terminal of the communication system.

In practice, each terminal of the communication system as shown in FIG. 3 is provided with a 48-bit address (called MAC address) fixedly coded or provided by an external source to each terminal. For example, the user must select the format shown in FIG. 4 to assign to these MAC addresses.

The high order two bits b0 and b1 are reserved to ensure compatibility with addresses defined according to the IEEE 802.2 standard. According to the 802.2 standard, the physical address of a terminal is coded in 48 bits. The higher order bit b0 indicates that it is an individual address or a group address (use of a group address in the destination address field of a frame allows some terminals to receive the same frame). The next bit (b1) serves to define a local or wide area natural address. Local addresses are managed by the responsible administrator of a given network and are meaningful only to that network, and global addresses (also called universal addresses) are managed by the IEEE, which is unique at the planet level and assigns them to various manufacturers. do. To ensure compatibility with addresses defined by the IEEE 802.2 standard, the choice here is therefore b0 = b1 = 1 (local group address according to the IEEE 802.2 standard).

The next 20 bits (b2-b21) are used to identify the point of convergence.

The next six bits (b22-b27) are used to identify the manufacturer of the terminal.

The last 20 bits (b28-b47) are used to identify the terminal.

In the first embodiment, a portion A1 of the 22-bit long address is stored at each access point and at each convergence point (i.e. in the equipment which connects the antenna to the terminal and in particular ensures the function of frequency interpretation). One portion A2 of the 26-bit long address is stored at each terminal connected to this convergence point.

In the second embodiment, the portion A1 of the 22-bit long address is stored at each convergence point and then stored at each terminal.

A 48-bit complete address that is a separate universal address (b0 = b1 = 0) and is used when the terminal is connected to a transmission medium in separate mode

A two-bit part (A2) of a 26-bit long address that corresponds to the two last groups of 6 and 20 bits, respectively, used when the terminal is connected in collective mode, in this case the 22-bit address stored at the convergence point It is joined together to form a 48-bit address that forms the physical address of the terminal.

In this second embodiment, what address should be used is indicated by the state variable S stored in the terminal, the value of which is defined at the time of installation of the terminal.

These two embodiments are compatible in the same communication system as one.

The terminal achieves a connection to the transmission system through the transmission of a connection message at compatible time intervals.

These connection messages are shown diagrammatically in FIG. In particular, they further comprise an address field F1 with the physical address of the terminal and a data field F2 with the characteristics of the requested connection (requested data rate, type of service ,,,,).

Therefore, the main station receiving this connection message can automatically know the group of terminals.

The main station 11 assigns a reservation to the user on the transmission medium in consideration of their membership of the user group so that the same time interval as one is not awarded to the same group of users on different carriers. An example method according to the invention of reservation grant is shown in FIG. 6. This method makes it possible to receive a n _i reserved in (T _i) each of the n terminals is connected to the communication system. In the embodiment described herein, each reservation is formed in pairs (time interval / carrier). The main station performs the following steps for the (T _i) and each terminal.

Step 100: This searches for belonging to the same group as the terminal T _i between the terminals T ₁ , ..., T _i-1 (ie between the terminals that have already granted the reservation). This group is called group G _k in the following description. If at least one terminal T ₁ , ..., T _i-1 belongs to the group G _k (arrow Y in the figure), the method proceeds to step 110, if not (arrow N in the figure). Proceeds to step 120.

- Step 110: The main station is granted n _i reserved in the terminal (T _i). The time intervals S _j (T _i ) (j = 1, ..., n _i ) for these reservations are selected so that they differ from the time intervals of reservations already granted to the terminals of the group G _k . This operation is shown diagrammatically in the figure by the following mathematical expression.

- step 120: the main station allocates the n _i access right in Fig terminal (T _i) in any way.

In an advantageous embodiment, the user, which is part of the user group, is a listening means for listening to assignments made by the main station to other users in their group, and the same means that the main station was granted to other users in the same group (on different carriers). The granting of the time interval includes control means for interfering with the use of the accessible time interval in dispute mode. The listening means is made such that the analysis is made of signal information transmitted by the main station 11, which information is provided to provide the structure of the input frame for each carrier. The listening facility may send to the user group a list of carriers that should be related to the list of carriers to be listened to, as well as a means for the main station to assign a carrier selected from among a sub-set of carriers to the same group of users. If included, means may be limited to any number of carriers.

The embodiment described above does not allow two users of the same group to avoid accessing the same argument time, unless this time interval has been granted to terminals of the same group by the main station. In another advantageous embodiment, this collision risk is limited by introducing a power measuring device prior to transmission. Determination of the power threshold considered normal for one single transmission and comparison of this threshold and power level determine if some users attempt to transmit data at the same time interval and if so interrupt the transmission.

One embodiment describes a terminal accessing a transmission medium by multiple access mechanisms based on time division combined with frequency assignment. This embodiment is not limiting. For example, the present invention is also applicable even if the multiple access mechanism to the transmission medium is a CDMA (code division multiple access) mechanism.

In the described embodiment, both transmission media 9 and 10 are formed by satellite links. However, the broadcast medium and return path may be of other types.

Claims (10)

A communication system comprising a transmission medium between at least one convergence point and a main station to service a group of users, The convergence point has a predetermined transmission capacity on the transmission medium, And means for assigning a reservation to a user on a transmission medium by the main station taking into account their membership of the user group and the transmission capacity of the convergence point. The method of claim 1, The user of the user group is provided with an identifier for identifying the group and the user to which he belongs, And transmission means for transmitting the identifier to a main station when the user connects with the communication system. The method of claim 1, The transmission medium comprises a satellite link, the convergence point comprises a collective antenna coupled to a satellite transmitter, and the satellite transmitter is coupled to the user. The method of claim 1, The transmission medium is designed to share at least time and frequency, and the reservation corresponds to at least transmission frequency for a predetermined time. A main station suitable for communicating over a transmission medium with at least one convergence point serving a group of users with a predetermined transmission capacity on the transmission medium, The station comprising means for assigning a reservation to a user on the transmission medium taking into account the capacity of the convergence point and their membership of the user group. The method of claim 5, The user of the group is provided with an identifier to identify the user and the group to which the group belongs, the station means for storing an identifier of the user connecting with the communication system, and means for determining membership of the user of the group from the identifier. Main station comprising a. A user terminal suitable for being part of a group of user terminals that access the transmission medium via a convergence point to communicate with the main station, The terminal comprises memory means for storing a first portion of an identifier identifying the user; Means for obtaining a second portion of an identifier identifying the convergence point, Means for combining the second portion and the first portion of the identifier together to form an identifier for the user, and And at least transmission means for transmitting said identifier to said main station when connected with a communication system. The method of claim 7, wherein Wherein said identifier comprises a physical address of a terminal sent to a main station of a connection message to a communication system. A method for assigning a reservation designed for use by a main station of a communication system to assign a reservation on a transmission medium to a user, the method comprising: Confirming whether the user belongs to a group of users connected to the transmission medium through a convergence point having a predetermined transmission capacity on the transmission medium, and And allocating the reservation in consideration of the transmission capacity of the convergence point and the membership of the user of the group of users. A method for identifying a user of a communication system comprising a user connected to a transmission medium via a convergence point, And wherein said method at least assigns to said user an identifier formed of two portions, a first portion identifying a convergence point and a second portion identifying a user.