Method and arrangement for channel allocation for data transmission between a main station and a plurality of substations
AssigneeU.S. Philips Corporation
InventorFrans Zijderhand
Life of this patent
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Abstract
In a method of data transmission from a plurality of sub-stations to a main station over a common channel which is subdivided into time slots whose length and synchronization are determined by a corresponding time slot distribution of a data transmission signal sent out by the main station, in which each sub-station has a predetermined probability p of transmitting a data packet in each time slot, the throughput of the communication channel is improved in that if the main station has correctly received in a specific time slot (n) a data packet coming from a specific sub-station, always a next time slot (n+j) will be reserved to be exclusively used by that specific sub-station.
Claims24
Method of transmitting data from a plurality of substations to a main station by way of a common channel including an up link and a down link, which channel is subdivided into time slots, the length and synchronization of which are determined by a corresponding time slot distribution of a data transmission signal transmitted on the downlink by the main station, each substation having a probability p, 0.ltoreq.p.ltoreq.1, of transmitting a data packet on the up link in each time slot;
- the method comprising:
- determining in the main station if the main station has correctly received, in the up link in a specific time slot n, a data packet coming from a specific substation, and
- if the data packet has been correctly received, reserving a next time slot n+j of the up link to be exclusively used by that specific substation, with j being a predetermined integer assigned to the substation such that j.gtoreq.2,
- wherein each substation, in transmitting each data packet, transmits at least one bit indicative of a time slot reservation relating to said next time slot, and
- wherein the messages to be sent by the substation are classified in various categories and said reservation applies only to messages in predetermined ones of these categories,
- the method further comprising the steps of:
- after a reservation sequence has been terminated by an incorrect reception of a data packet in the time slot n, continuing to reserve the time slot n+j and releasing the time slot n+2j, and
- for messages in a predetermined category, if the first data packet has not been received correctly, setting the probability of retransmission of that first data packet in the time slot n+j equal to 1.
A method of transmitting data from a plurality of substations to a main station by way of a common channel, including an up link and a down link, which channel is divided into time slots, the length and synchronization of which are determined by a corresponding time slot distribution of a data transmission signal transmitted on the down link by said main station, each substation having a probability p, with 0.ltoreq.p.ltoreq.1 of transmitting a data packet on the up link in each time slot, the method comprising:
- determining if the main station has correctly received, on the up link, in a specific time slot, a data packet coming from the specific substation, and if it has, reserving a next time slot to be exclusively used by that specific substation with j being an integer such that j is .gtoreq.2;
- transmitting a data packet on the down link from the main station in each time slot, the data packet comprising at least one bit which is indicative of the received condition of the data packet received in the previous time slot and at least one separate bit indicative of the reservation of the next time slot;
- and after a reservation sequence has been terminated by an incorrect reception of a data packet in a time slot n, continuing to reserve the time slot n+j and releasing the time slot n+2j.
Method for reducing data collisions in a data transmission system, which system includes a main station and a plurality of substations that communicate with the main station via a common channel, the channel being subdivided into time slots, which time slots have a length and synchronization determined by a corresponding time slot distribution of a data transmission signal transmitted by the main station, the method comprising the steps of:
- in the substations, transmitting information to the main station, each substation having a respective probability p of transmitting a data packet in any given time slot;
- in the main station, if there is successful reception of a particular data packet, in a first time slot n, transmitting a signal indicating successful reception in a time slot having a fixed relationship with the time slot n and
- in one of the substations, which one transmitted the particular data packet, reserving time slot n+j in response to the signal indicating successful reception, and where j is a predetermined value;
- so that the substations deduce which time slot has been reserved in the data transmission system without the main station transmitting an explicit indication of
- which time slot has been reserved or
- which substation the time slot has been reserved for, and
- where n and j are integers with j.gtoreq.2 and each respective probability p is a respective real number between 0 and 1.
A substation for use in a transmission system which comprises a main station and a plurality of substations similar to the substation, the substation comprising
- means for communicating with the main station via a common channel, the channel being subdivided into time slots, which time slots have a length and synchronization determined by a corresponding time slot distribution of a data transmission signal transmitted by the main station;
- and
- processing means for carrying out the following process:
- transmitting information to the main station, the substation having a respective probability p of transmitting a data packet in any given time slot;
- receiving from the main station, a signal indicating successful reception, in a time slot having a fixed relationship with the time slot n, if the main station successfully receives the data packet in a first time slot n;
- and
- reserving time slot n+j in response to the signal indicating successful reception, where j is a predetermined value;
- so that the substation deduces which time slot has been reserved in the data transmission system without the main station transmitting an explicit indication of which time slot has been reserved or
- which substation the time slot has been reserved for, and
- where n and j are integers with j.gtoreq.2 and each respective probability p is a respective real number between 0 and 1.
A method for transmitting data from a plurality of substations to a main station by way of a common channel, which channels includes an up link and a down link and is divided into time slots, the time slots having a length and a distribution determined by a corresponding time slot distribution of a data transmission signal transmitted on the down link by the main station, each subdivision having a probability p, 0.ltoreq.p.ltoreq.1, of transmitting a data packet on the up link in any given time slot;
- the method comprising:
- assigning to each substation a respective value of a numerical identifier j having integral values ranging from at least 2 onward;
- determining, in the main station, if the main station has correctly received in the up link in a specific time slot n a data packet coming from a specific substation, and
- in case of a positive result of the determining step, reserving a next time slot n+j of the up link to be exclusively used by the specific substation, with j having the numerical value assigned to said substation, so that said substation may uninterruptedly continue to transmit data packets in time slots which follow the time slot n at time invariant integral multiples of the value of j assigned to said substation.
Dependencies are inferred from the claim text.