Method for transmitting data to user equipments, communication system, base station and user equipment
A method is provided for transmitting data to user equipments, a communication system, a base station and a mobile station. Data is transmitted to user equipments from a first base station (BBS) and from second base stations (CBS) in a time division multiplexed manner in frames (F). Each frame (F) has a first sub-frame and a second sub-frame. The user equipments are located in cells, each cell a second base station (CBS). Data is transmitted wirelessly, during a first sub-frame of a frame, data from the first base station (BBS) to user equipments in a plurality of cells. Data is transmitted wirelessly, during the second sub-frame of the frame (F), from second base station (CBS) to at least one the plurality of user equipments. The data being transmitted from the first base station (BBS) is also transmitted by the second base station (CBS) to at least one of the plurality of cells.
1. Method for transmitting data to user equipments, from a first base station (BBS) and from second base stations (CBS) in a time division multiplexed manner in frames (F), each frame (F) having a first sub-frame and a second sub-frame, the user equipments being located in cells, each cell comprising a second base station (CBS),
transmitting wirelessly, during a first sub-frame of a frame, data from the first base station (BBS) to user equipments in a plurality of cells,
transmitting wirelessly, during the second sub-frame of the frame (F), data from second base station (CBS) to at least one the plurality of user equipments,
whereby the data being transmitted from the first base station (BBS) is at least partially also transmitted by the second base station (CBS) to at least one of the plurality of cells.
2. Method according to claim 1 , characterized in that the second base station (CBS) receives wirelessly data from the first base station (BBS) during the first sub-frame and whereby the second base station (CBS) retransmits wirelessly the data received from the first base station (BBS) to at least one of the plurality of user equipments.
3. Method according to claim 2 , characterized in that the second base station (CBS) retransmits the data at least partially during the second sub-frame.
4. Method according to claim 2 , characterized in that the second base station (CSB) retransmits the data at least partially during the first sub-frame.
5. Method according to claim 1 , characterized in that the first base station (BBS) sends the same data in a first frequency domain (high MSC) and concurrently in a second frequency domain (low MSC) during the first sub-frame.
6. Method according to claim 2 , characterized in that the second base station (CBS) retransmits the data upon request of one of the user equipments to the one of the user equipments having sent the request.
7. Method according to claim 6 , characterized in that the request is a negative acknowledgement signal (B-NACK).
8. Method according to claim 6 , characterized in that the request includes an information which of the data packets are to be retransmitted.
9. Method according to claim 2 , characterized in that the second base station (CBS) retransmits data during the frame (F) in which that the second base station receives the data from the first base station (BBS).
10. Method according to claim 2 , characterized in that a data being retransmitted by the second base station (CBS) is coded by the same modulation-coding scheme as the modulation-coding scheme that the first base station (BBS) used to code said data packet.
11. Method according to claim 2 , characterized in that the retransmitted data is sent during a forwarding phase and the second base station (CBS) sends a signal indicating the length of forwarding phase to the user equipment at the beginning of each forwarding phase.
12. Method according to claim 2 , characterized in that the second base station (CBS) sends a signal indicating the modulation coding scheme (MCS) of the retransmission of data.
13. Method for receiving, by user equipment, data from a first base station (CBS) and from a second base station (BBS) in frames, each frame (F) having a first sub-frame and a second sub-frame,
receiving, in the first sub-frame, data packets from the first base station (BBS),
decoding the data received from the first base station (BBS),
sending to the second base station (CBS) a request for data packets that were received from the first base station (BBS) with errors.
14. Method according to claim 13 , characterized in that the request is a negative acknowledgement signal (B-NACK).
15. Method according to claim 13 , characterized in that the request includes the number of the data packet to be retransmitted.
16. Method according to claim 13 , characterized in a step of
combining the data packets retransmitted from second base station (CBS) with the data packets received from the first base station (BBS).
17. Base station for transmitting data to user equipments in a time division multiplexed manner in frames, each frame having a first sub-frame and a second sub-frame,
a transmit unit for transmitting wirelessly, during the second sub-frame of a frame, data from the second base station (CBS) to the plurality of user equipments,
a first receive unit for receiving wirelessly data from another base station during the first sub-frame, and a retransmit unit for retransmitting wirelessly data received from the other base station (BBS) to at least one of the plurality of user equipments.
18. Base station according to claim 17 , characterized in a second receive unit for receiving a request from a user equipment for retransmitting data, whereby the request is forwarded to the retransmit unit to retransmit the data if it is requested by the request from the user equipment.
19. Base station according to claim 18 , characterized in that the request comprises a information which data packets of the data received by the first receive unit is requested and that the retransmit unit retransmits only the requested data packets to the user equipment.
20. User equipment for receiving wirelessly data from a first base station (BBS) and from a second base station (CBS) in a time division multiplexed manner in frames, each frame having a first sub-frame and a second sub-frame,
a receive unit for receiving, in the first sub-frame, data packets from a first base station (BBS),
a decode unit for decoding the data received from the first base station (BBS),
an acknowledgement unit to send to the second base station (CBS) a request for data packets that were not entirely received from the first base station (BBS).
21. User equipment according to claim 20 , characterized in that the request comprises an information indicating which data packets are requested.
22. Communication system for transmitting data to user equipments in a time division multiplexed manner in frames, each frame having a first sub-frame and a second sub-frame,
a first base station (BBS) for transmitting wirelessly, during a first sub-frame of a frame (F), data to a plurality of user equipments,
a second base station for transmitting wirelessly, during the second sub-frame of a frame (F), data from to the plurality of user equipments,
whereby, the second base station (CBS) comprises a first receive unit for receiving data from the first base station (BBS) during the first sub-frame,
and a retransmit unit for retransmitting wirelessly data received from the first base station (BBS) to at least one of the plurality of user equipments.