Cellular Network Broadcasting

Abstract

Provided is a method and a system for broadcasting data in a cellular network which assigns the data to a plurality of Packet Data Convergence Protocol, PDCP, Protocol Data Units, PDUs, assigns the PDCP PDUs to a Radio Link Control, RLC, Service Data Unit, SDU, interleaves segments of the RLC SDU and assigns the interleaved segments to a plurality of Medium Access Control, MAC, SDUs.

Claims

1. A method for broadcasting data in a cellular network, the method comprising: assigning the data to a plurality of Packet Data Convergence Protocol, PDCP, Protocol Data Units, PDUs; assigning the PDCP PDUs to a Radio Link Control, RLC, Service Data Unit, SDU; interleaving segments of the RLC SDU; and assigning the interleaved segments to a plurality of Medium Access Control, MAC, SDUs.

2. The method of claim 1, wherein the data assigned to the PDCP PDUs is error coded; or assigning the PDCP PDUs to the RLC SDU includes error coding the PDCP PDUs or error coding an RLC PDU comprising the RLC SDU.

3. The method of claim 1, wherein the RLC SDU is comprised in an RLC PDU with a length of 15000 bytes or more.

4. The method of claim 1, wherein a/the length of the RLC PDU is n times a length of one MAC SDU with n being a positive integer.

5. The method of claim 1, further comprising: transmitting MAC PDUs that carry segments of different RLC SDUs alternatingly.

6. The method of claim 5, wherein a single frame comprises only one of said MAC PDUs that carry segments of different RLC SDUs.

7. The method of claim 1, wherein a single frame comprises MAC PDUs that carry segments of different RLC SDUs.

8. The method of claim 1, wherein the cellular network is a 3G, a 4G, or a 5G network.

9. A system for broadcasting data over a cellular network, the system being configured to: assign the data to Service Data Units, SDUs, of a plurality of Packet Data Convergence Protocol, PDCP, Protocol Data Units, PDUs; assign the PDCP PDUs to a Radio Link Control, RLC, SDU; interleave segments of the RLC SDU; and assign the interleaved segments to Medium Access Control, MAC, SDUs.

10. The system of claim 9, wherein the data assigned to the PDCP PDUs is error coded or assigning the PDCP PDUs to the RLC SDU includes error coding the PDCP PDUs or error coding an RLC PDU comprising the RLC SDU.

11. The system of claim 9, wherein the RLC SDU is comprised in an RLC PDU having a length of 15000 bytes or more.

12. The system of claim 9, wherein a length of the RLC PDU is n times a length of a MAC SDU with n being a positive integer.

13. The system of claim 9, wherein the system is configured to: alternatingly transmit MAC PDUs which carry segments of different RLC SDUs.

14. The system of claim 13, wherein only one MAC PDU which carries segments of different RLC SDUs is transmitted within a single frame.

15. The system of claim 9, wherein the system is configured to: transmit MAC PDUs which carry segments of different RLC SDUs in a single frame.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0026] The foregoing aspects and many of the attendant advantages will become more readily appreciated as the same becomes better understood by reference to the following description of embodiments, when taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts throughout the various views, unless otherwise specified.

[0027] FIG. 1 illustrates a cellular network broadcasting scenario;

[0028] FIG. 2 illustrates an exemplary protocol stack;

[0029] FIG. 3 illustrates RLC SDU interleaving;

[0030] FIG. 4 illustrates the transmission of the interleaved segments according to a first exemplary transmission scheme;

[0031] FIG. 5 illustrates the transmission of the interleaved segments according to a second exemplary transmission scheme; and

[0032] FIG. 6 shows a flow-chart of the transmission process.

[0033] Notably, the drawings are not drawn to scale and unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

DESCRIPTION OF EMBODIMENTS

[0034] FIG. 1 shows a system 10 for broadcasting data over a cellular network. The system 10 comprises a base station 100 (e.g., an evolved Node B, eNodeB) and several mobile stations 200, 210, 220, 230, 240 (e.g., user equipments, UEs) which receive data from the base station 100. As shown in FIG. 2, the base station 100 is configured to assign the data (which is to be broadcasted) to PDCP PDUs. The base station 100 then assigns the PDCP PDUs to RLC PDUs. The RLC PDUs are then assigned to MAC PDUs and the MAC PDUs are mapped to transport blocks in the physical layer. The mobile station 200 (and the other mobile stations 210, 220, 230, 240) may perform reverse assignments to recover the data.

[0035] As illustrated in FIG. 3, an RLC SDU may be segmented and the segments 1-9 may be interleaved before assigning the interleaved segments to one or more MAC SDUs. The interleaving may spread the PDCP PDUs, thereby reducing the risk of irrecoverable data loss in case of temporary signal degradation. For example, the length of an RLC PDU may be n times a length of a MAC SDU with n being a positive integer (e.g., 8, 9, 10, 11, 12, etc.). The resulting RLC PDU may have a length of 10.000 bytes or more, or 15.000 bytes or more. This may enforce that an RLC PDU is spread over multiple MAC PDUs/transport blocks/subframes or system frames.

[0036] Moreover, the RLC PDUs, RLC SDUs, PDCP PDUs, PDCP SDUs (or data contained in said SDUs/PDUs) may be error (correction) coded (for example, based on a block code). Hence, faulty blocks may not be discarded at the mobile station 200 (and the other mobile stations 210, 220, 230, 240) but used for recovering the error (correction) coded data. Hence, no CRC may be applied to the MAC PDUs or the MAC PDUs may be provided to the RLC layer despite CRC errors.

[0037] As shown in FIG. 4, the blocks carrying the data of consecutive RLC PDUs (four consecutive RLC-PDUs in this particular example) may be transmitted alternatingly. For example, a first block carrying a first segment of the interleaved segments of a first RLC PDU may be followed by a second block carrying a first segment of the interleaved segments of a second RLC PDU and so forth. In another example, the alternatingly transmitted blocks may carry data of RLC PDUs that are assigned to different logical channels (e.g., different broadcast channels).

[0038] As shown in FIG. 5, only a subset of subframes (one subframe of a system frame in this particular example) may be configured for eMBMS and the data of consecutive RLC PDUs (four consecutive RLC-PDUs in this example) may be transmitted alternatingly in the subframes which are configured for eMBMS. Hence, in a first system frame, a first block carrying a first segment of the interleaved segments of a first RLC PDU may be transmitted and in a (consecutive) second system frame, a second block carrying a first segment of the interleaved segments of a second RLC PDU may be transmitted.

[0039] FIG. 6 shows a flow-chart of the transmission process. At step 310, the base station 100 assigns data that is to be broadcasted to the mobile stations 200, 210, 220, 230, 240 to a plurality of PDCP PDUs. At step 320, the PDCP PDUs are assigned to an RLC SDU. After interleaving segments of the RLC SDU in step 330, the interleaved segments are assigned to a plurality of MAC SDUs in step 340. The MAC SDUs may then be provided with a headers and transmitted in transport blocks over the air interface to the mobile stations 200, 210, 220, 230, 240. The mobile stations 200, 210, 220, 230, 240 may then apply an error correcting code to recover the data in case of transmission errors.

REFERENCE SIGNS

[0040] 1-9 segments [0041] 10 system [0042] 100 base station [0043] 200 mobile station [0044] 210 mobile station [0045] 220 mobile station [0046] 230 mobile station [0047] 240 mobile station [0048] 310 process step [0049] 320 process step [0050] 330 process step [0051] 340 process step [0052] H header