Multicast-based content transmitting system and method, and device and method for estimating high-speed movement

1. A multicast-based contents transmission system, comprising:

a contents providing apparatus configured to

create N×M multicast stream channels respectively having N different transmission start times and M different transmission rates,

provide an N×M multicast stream channel list including N×M multicast stream channel information including information on contents to be transmitted, a transmission start time and a transmission rate of each channel, and

transmit the contents through a channel among the N×M multicast stream channels; and

a user terminal configured to

receive the N×M multicast stream channel list through a network from the contents providing apparatus,

confirm an available transmission rate of the network,

select a multicast stream channel from the received N×M multicast stream channel list according to the confirmed available transmission rate of the network, and

receive the transmitted contents through the selected multicast stream channel,

wherein, when a retransmission of the contents is requested, the user terminal is configured to

select a candidate multicast stream channel list by confirming an available transmission rate of the user terminal at the time of the requesting retransmission of the contents with transmission rates of the N×M multicast stream channel list, and

select a multicast stream channel for retransmission from the selected candidate multicast stream channel list by comparing a contents retransmission request time with transmission start times of candidate multicast stream channels in the selected candidate multicast channel list,

wherein the selected multicast stream channel for retransmission has a transmission start time later than the contents retransmission request time, and closest to the contents retransmission request time among the candidate multicast stream channels,

wherein the selected multicast stream channel has a transmission rate lower than the confirmed available transmission rate of the network and highest among candidate multicast stream channels in the received N×M multicast stream channel list,

wherein the user terminal is configured to store the received contents,

wherein, when a number of lost packets of the received contents is equal to or below a reference value, the user terminal is configured to restore contents from the lost packets using a forward error correction method,

wherein, when the number of lost packets exceeds the reference value, the user terminal is configured to delete packets of the received contents, and request retransmission of the received contents, and

wherein the user terminal is configured to confirm loss of packets in the received contents and restore the lost packets or request retransmission of the received contents when the packets cannot be restored.

2. The system according to claim 1 , the contents providing apparatus is configured to:

create the N×M multicast stream channels configured of

N multicast stream channels having transmission start times arranged at time intervals of T, and

M multicast stream channels of different transmission rates configured in each of the N multicast stream channels.

3. The system according to claim 2 , the contents providing apparatus is configured to create the contents to be transmitted on the N×M multicast stream channels in the form of a packet.

4. A user terminal for receiving a multicast-based contents from a contents providing apparatus, the user terminal comprising:

a network interface configured to

receive an N×M multicast stream channel list including N×M multicast stream channel information configured of contents to be transmitted, a transmission start time and a transmission rate of each channel,

transmit, to the contents providing apparatus, a channel selection signal for selecting a multicast stream channel from the received N×M multicast stream channel list, and

receive contents through the multicast stream channel corresponding to the channel selection signal; and

a processor configured to

confirm an available transmission rate of a network, and

select the multicast stream channel from the received N×M multicast stream channel list using the confirmed available transmission rate and a contents transmission request time, and

a contents storage configured to store the received contents,

wherein, when a number of lost packets of the received contents is equal to or below a reference value, the processor is configured to restore contents from the lost packets using a forward error correction method,

wherein, when the number of lost packets exceeds the reference value, the processor is configured to delete packets of the received contents, and request retransmission of the received contents,

wherein the processor is configured to confirm loss of packets in the received contents and restore the lost packets or request retransmission of the received contents when the packets cannot be restored,

wherein, when a retransmission of the received contents is requested, the processor is configured to select

a candidate multicast stream channel list by confirming the available transmission rate of the network at the time of the requesting retransmission of the contents with transmission rates of the N×M multicast stream channel list, and

a multicast stream channel for retransmission from the selected candidate multicast channel list by comparing a contents retransmission request time with transmission start times of the selected multicast channel list,

wherein the selected multicast stream channel for retransmission has a transmission start time later than the contents retransmission request time, and closest to the contents retransmission request time among the candidate multicast stream channels

wherein the processor is configured to select the multicast stream channel from the received N×M multicast stream channel list by

selecting the multicast stream channel having a transmission rate lower than the confirmed available transmission rate of the network and highest among candidate multicast stream channels in the received N×M multicast stream channel list.

5. The user terminal according to claim 4 , wherein the processor is configured to select the multicast stream channel from the received N×M multicast stream channel list by

selecting a plurality of multicast stream channels having transmission rates lower than the available transmission rate from the received N×M multicast stream channel list, and

selecting the multicast stream channel having a transmission start time closest to the contents transmission request time in the N×M multicast stream channel list among the selected plurality of multicast stream channels.

6. The user terminal according to claim 4 , wherein the processor is configured to select the multicast stream channel from the received N×M multicast stream channel list by

selecting the candidate multicast stream channels having transmission start time later than the contents transmission request time in the N×M multicast stream channel list from the provided N×M multicast stream channel list.

7. A multicast-based contents transmission method, comprising:

creating, by a contents providing apparatus, N×M multicast stream channels respectively having N different transmission start times and M different transmission rates and an N×M multicast stream channel list including N×M multicast stream channel information configured of contents to be transmitted, a transmission start time and a transmission rate of each channel;

transmitting, by the contents providing apparatus, the N×M multicast stream channel list to a user terminal;

confirming, by the user terminal, an available transmission rate of the network;

selecting, by the user terminal, a multicast stream channel from the N×M multicast stream channel list according to the confirmed available transmission rate of the network;

transmitting, by the user terminal, a channel selection signal for selecting the multicast stream channel for transmitting contents using the N×M multicast stream channel information of the transmitted N×M multicast stream channel list to the contents providing apparatus;

transmitting, by the contents providing apparatus, the contents to the user terminal using a multicast stream channel corresponding to the channel selection signal;

storing, by the user terminal, the transmitted contents through the selected multicast stream channel;

when a number of lost packets of the transmitted contents is equal to or below a reference value, restoring, by the user terminal, contents from the lost packets using a forward error correction method; and

when the number of lost packets exceeds the reference value, the user terminal

deleting packets of the transmitted contents,

requesting a retransmission of the transmitted contents,

selecting a candidate multicast stream channel list by confirming an available transmission rate of the user terminal at the time of the requesting retransmission of the contents with transmission rates of the N×M multicast stream channel list, and

selecting a multicast stream channel for retransmission from the selected multicast stream channel list by comparing a contents retransmission request time with transmission start times of candidate multicast stream channel in the selected multicast channel list,

wherein the selected multicast stream channel for retransmission has a transmission start time later than the contents retransmission request time, and closest to the contents retransmission request time among the candidate multicast stream channels,

wherein the selected multicast stream channel has a transmission rate lower than the available transmission rate of the network and highest among candidate multicast stream channels in the transmitted N×M multicast stream channel list, and

wherein the user terminal confirms loss of packets in the transmitted contents and restore the lost packets or request retransmission of the transmitted contents when the packets cannot be restored.

8. A multicast-based contents reception method of a user terminal, the method comprising the steps of:

(a) receiving, by the user terminal, an N×M multicast stream channel list including information on multicast stream channels configured of contents information, a transmission start time and a transmission rate;

(b) selecting, by the user terminal, a multicast stream channel by comparing the transmission start time, the transmission rate and the contents information of the received N×M multicast stream channel list with an available transmission rate of a network measured by the user terminal, a contents transmission request time and information on contents to be received;

(c) transmitting, by the user terminal, a channel selection signal for using the selected multicast stream channel; and

(d) receiving, by the user terminal, contents using the selected multicast stream channel;

(e) storing, by the user terminal, the received contents;

(f) when a number of lost packets of the received contents is equal to or below a reference value, restoring, by the user terminal, contents from the lost packets using a forward error correction method; and

(g) when the number of lost packets of the received contents exceeds the reference value, the user terminal,

deleting packets of the received contents,

requesting retransmission of the received contents,

selecting a candidate multicast stream channel list by confirming an available transmission rate of the user terminal at the time of the requesting retransmission of the contents with transmission rates of the N×M multicast stream channel list, and

selecting a multicast stream channel for retransmission from the selected multicast stream channel list by comparing a contents retransmission request time with transmission start times of candidate multicast stream channels in the selected candidate multicast channel list,

wherein the selected multicast stream channel for retransmission has a transmission start time later than the contents retransmission request time, and closest to the contents retransmission request time among the candidate multicast stream channels in the selected candidate multicast channel list,

wherein the selected multicast stream channel has a transmission rate lower than the available transmission rate of the network and highest among candidate multicast stream channels in the received N×M multicast stream channel list, and

wherein the user terminal confirms loss of packets in the transmitted contents and restore the lost packets or request retransmission of the transmitted contents when the packets cannot be restored.

9. The method according to claim 8 , wherein step (b) includes the steps of:

(b-1) selecting, by the user terminal, a plurality of multicast stream channels having transmission rates lower than the available transmission rate of the network from the received N×M multicast stream channel list; and

(b-2) selecting, by the user terminal, the multicast stream channel having a transmission start time closest to the contents transmission request time in the N×M multicast stream channel list among the selected plurality of multicast stream channels.

10. The method according to claim 8 , wherein step (b) includes the steps of:

(b-1) selecting, by the user terminal, a plurality of multicast stream channels having transmission start times later than the contents transmission request time in the N×M multicast stream channel list from the received N×M multicast stream channel list; and

(b-2) selecting, by the user terminal, the multicast stream channel having a highest transmission rate among the selected plurality of multicast stream channels.