METHOD OF TRANSMITTING DATA BETWEEN NETWORK DEVICES OVER A NON-DETERMINISTIC NETWORK

Abstract

A method of transmitting data between network devices over a non-deterministic network with a multiple channel access method, wherein it is not possible to determine, whether a network device can access the non-deterministic network, wherein the non-deterministic network comprises a plurality of network devices. The method includes the steps of: synchronising clocks of individual network devices of the plurality of network devices with each other, dividing time available for transmitting the data into timeslots, designating respective pairs of consecutive timeslots to the individual network devices of the plurality of network devices, wherein an individual network device transfers data only during the respective pairs of timeslots designated to it and evaluating, whether a network device of the plurality of network devices shall retransmit data, which it has already transmitted during a first timeslot of a pair timeslot, within the second timeslot of the pair of timeslots.

Claims

1. A method of transmitting data between network devices (110, 120, 130) over a non-deterministic network (100) with a multiple channel access method, wherein the non-deterministic network (100) comprises a plurality of network devices (110, 120, 130), comprising the steps of: synchronising clocks of individual network devices of the plurality of network devices (110, 120, 130) with each other (210), dividing time available for transmitting the data into timeslots (220), designating respective pairs of consecutive timeslots to the individual network devices of the plurality of network devices (110, 120, 130), wherein an individual network device (110, 120, 130) transfers data only during the respective pairs of timeslots designated to it, and evaluating, whether a network device of the plurality of network devices (110, 120, 130) shall retransmit data, which it has already transmitted during a first timeslot of a pair of timeslots, within the second timeslot of the pair of timeslots (340).

2. The method of claim 1, wherein media data is transmitted over the non-deterministic network (100) between network devices (110, 120, 130).

3. The method of claim 1, wherein data with low latency is transmitted over the non-deterministic wireless (100) network between the network devices (110, 120, 130).

4. The method of claim 1, wherein the evaluation is performed depending on a Time to Live (TTL) of the data to be transmitted.

5. The method of claim 1, wherein the timeslots are designated to the network devices (110, 120, 130) with a fixed offset at the beginning of the timeslot.

6. The method of claim 1, wherein a first clock of a first network device of the plurality of network devices (110, 120, 130) shall be synchronised (210) with a second clock of a second network device of the plurality of network devices (110, 120, 130), wherein the first clock of the first network device and the second clock of the second network device differ by an offset and the offset changes over time due to a drift, wherein synchronising the first clock of the first network device with the second clock of the second network device (210) comprises the steps of: determining the drift between the first clock of the first network device and the second clock of the second network device in a first step, compensating for the determined drift between the first clock of the first network device and the second clock of the second network device in a second step, and determining and compensating for the offset between the first clock of the first network device and the second clock of the second network device in a third step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will now be described further, by way of example, with reference to the accompanying drawings, in which

[0044] FIG. 1 schematically shows a non-deterministic network, which is designed to execute a preferred embodiment of a method according to the invention,

[0045] FIG. 2 schematically shows a preferred embodiment of a method according to the invention as a flow chart, and

[0046] FIG. 3 schematically shows a preferred embodiment of a method according to the invention as a flow chart.

DETAILED DESCRIPTION

[0047] In FIG. 1 a non-deterministic network, in particular a wireless network, which is designed to execute a preferred embodiment of a method according to the invention, is schematically depicted and labelled as 100.

[0048] The wireless network 100 comprises a plurality of network devices. Three network devices 110, 120, and 130 are depicted exemplarily in FIG. 1. The network devices 110, 120, 130 are connected with each other by a wireless link, designated 101.

[0049] The network devices 110, 120, 130 are considered as slaves. A master 150 constitutes a further network device, which controls the wireless network 100. The master 150 is for example designed as a station controller of the wireless network 100. The master 150 particularly controls data transmission between the network devices 110, 120, 130 over the wireless network 100.

[0050] The wireless network 100 is particularly designed as a media network. The individual network devices 110, 120, 130 are particularly designed as media devices such as television devices, media players, and/or hi-fi equipment. The network devices 110, 120, 130 exchange data over the wireless network 100, particularly media data with low latency. In order to coordinate this data exchange, the master 150 is particularly designed to execute a preferred embodiment of a method according to the invention.

[0051] This preferred embodiment of the method according to the invention is depicted in FIG. 2 schematically as a flow chart.

[0052] In step 210 the master 150 during a synchronisation phase synchronises clocks of the individual network devices 110, 120, and 130. Time distributed by a clock of the master 150 is an absolute time. The clocks of the network devices 110, 120, and 130 are adjusted to be in lock with the clock of the master 150. Particularly, the master 150 and the network devices 110, 120, and 130 exchange appropriate synchronisation-data, such as e.g. sync messages and delay requests and delay responses.

[0053] With the clocks of the network devices 110, 120, 130 and the master 150 synchronised, the master performs a scheduling phase in step 220.

[0054] The master divides the time available for transmission of data in the wireless network 100 into timeslots. Moreover the master 150 designates respective pairs of consecutive timeslots to the individual network devices 110, 120, 130. The network devices 110, 120, 130 transmit data only during their designated respective pairs of timeslots.

[0055] In step 230 a certain pair of timeslots begins. In step 240, the corresponding network device, e.g. 110, transmits data over the wireless network 100 to a receiving entity, e.g. a media receiver device, during this pair of timeslots. Indicated by label 250, after this pair of timeslots, the consecutive pair of timeslots begins and the corresponding network device, e.g. 120, transmits data over the wireless network 100.

[0056] In FIG. 3 the process of transmitting data according to step 240 is depicted in detail, schematically as a flow chart.

[0057] In step 310 a first timeslot of a pair of timeslots begins. A packet trigger concerning specific data and/or a specific data packet is activated/triggered. Thus, the corresponding network device, e.g. 110, transmits this specific data/data packet in step 320. In step 330 the transmission of this specific data/data packet is completed and the first timeslot of said pair of timeslots ends.

[0058] In step 340 it is evaluated, whether the network device 110 shall retransmit the specific data/data packet in a second timeslot of the current pair of timeslots.

[0059] In step 340 it is evaluated, whether the packet duration is smaller than Time to Live (TTL) of the certain data/data packet

[0060] If this is the case (label 341), the specific data/data packet is retransmitted in step 350 in the second timeslot of the pair of timeslots. If this is not the case (label 342), step 360 is performed. Step 360 is also performed after the retransmitting of the specific data/data packet in step 350.

[0061] In step 360 the network device 110 waits until another packet trigger concerning data and/or data packets is activated/triggered. Then the network device 110 begins again with step 310. Steps 310 to 360 are performed until the timeslot of network device 110 ends.