Combined layer 3 and downlink control information (DCI) signaling of virtual cell id
地域：
Stockholm
摘要
Methods, network nodes and wireless devices for determining a virtual cell index field length. According to one aspect, a method of determining a length of a virtual cell index field to be transmitted with downlink control information, DCI, is performed where the virtual cell index field length for transmitting a virtual cell index to a wireless device is dynamically settable. The method includes determining a number of configured virtual cell identities, ID. The method includes transmitting the configured virtual cell identities to the wireless device. When a number of configured virtual cell IDs is greater than one, the method includes selecting a virtual cell index corresponding to a particular one of the virtual cell IDs and setting the virtual cell index field length based on the number of virtual cell IDs. The method includes transmitting the selected virtual cell index in the virtual cell index field to the wireless device.
說明書
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This application is a Submission Under 35 U.S.C. § 371 for U.S. National Stage Patent Application of International Application Number: PCT/EP2017/056136, filed Mar. 15, 2017 entitled “COMBINED LAYER 3 AND DOWNLINK CONTROL INFORMATION (DCI) SIGNALING OF VIRTUAL CELL ID,” the entirety of which is incorporated herein by reference.
This disclosure relates to wireless communication, and in particular to efficient combined Layer 3 (L3) and downlink control information (DCI) signaling of virtual cell identity.
In a long term evolution (LTE) wireless communication network, the physical downlink control channel (PDCCH) is used to send DCI messages to wireless devices, for example, to schedule physical downlink shared channel (PDSCH) transmissions or to grant permission for physical uplink shared channel (PUSCH) transmissions. Pseudo-random reference symbol sequences used for the demodulation reference signal (DMRS) associated with the PDSCH and PUSCH transmissions depend on several variables used to initialize the pseudo-random sequence generation function. In many cases, the reference symbol sequence will depend on the physical cell identity of the physical cell serving the wireless device. The physical cell identity is conveyed by the primary synchronization signals (PSS) and secondary synchronization signals (SSS). However, there are also cases—for example, with coordinated multipoint (CoMP) transmission—where it is useful to not tie the reference symbol sequence generation directly to the physical cell identity. For these cases, the concept of a virtual cell identity has been introduced in LTE systems.
權(quán)利要求
What is claimed is:1. A method for use in a network node of determining a length of a virtual cell index field to be transmitted with downlink control information, DCI, the virtual cell index field length for transmitting a virtual cell index to a wireless device being dynamically settable, the method comprising:determining a number of configured virtual cell identities, IDs; and when a number of configured virtual cell IDs is greater than one:selecting a virtual cell index corresponding to a particular one of the virtual cell IDs; setting the virtual cell index field length based on the number of virtual cell IDs; and transmitting the selected virtual cell index in the virtual cell index field to the wireless device; and when the number of configured virtual cell IDs is zero, setting the length of the virtual cell index field to be of length zero and transmitting no virtual cell IDs to the wireless device, thereby causing the wireless device to use a physical layer cell identity to generate a pseudo-random sequence. 2. The method of claim 1 , further comprisingtransmitting the configured virtual cell identities to the wireless device. 3. The method of claim 1 , wherein when the number of virtual cell IDs is one, setting the length of the virtual cell index field to be of length zero and transmitting a single virtual cell ID to the wireless device, thereby causing the wireless device to use the single virtual cell ID to generate a pseudo-random sequence. 4. The method of claim 1 , wherein the pseudo-random sequence is one of a reference sequence and a scrambling sequence. 5. The method of claim 1 , wherein the length of the virtual cell index field is log2(N) bits where N is the number of configured virtual cell IDs. 6. The method of claim 1 , wherein an identity of the wireless device is used to generate a pseudo-random sequence. 7. A network node for determining a length of a virtual cell index field in downlink control information, DCI, the virtual cell index field length for transmitting a virtual cell index to a wireless device being dynamically settable, the network node comprising:processing circuitry configured to:determine a number of configured virtual cell identities, IDs; and when a number of configured virtual cell IDs is greater than one:select a virtual cell index of a particular one of the virtual cells; and set the virtual cell index field length based on the number of virtual cell IDs; and when the number of configured virtual cell IDs is zero, set the length of the virtual cell index field to be of length zero and transmit no virtual cell IDs to the wireless device, thereby causing the wireless device to use a physical layer cell identity to generate a pseudo-random sequence; and a transmitter configured to transmit the selected virtual cell index in the virtual cell index field to the wireless device. 8. The network node of claim 7 , wherein the transmitter is further configured to transmit the configured virtual cell identities to the wireless device. 9. The network node of claim 7 , wherein when the number of virtual cells configured for the wireless device is one, the processing circuitry is further configured to set the length of the virtual cell index field to be of length zero, in which case one virtual cell ID is transmitted to the wireless device to cause the wireless device to use the one configured virtual cell identity to generate a pseudo-random sequence. 10. The network node of claim 7 , wherein the pseudo-random sequence is one of a reference sequence and a scrambling sequence. 11. The network node of claim 7 , wherein the length of the virtual cell index field is log2(N) bits where N is the number of configured virtual cell IDs. 12. The network node of claim 8 , wherein an identity of the wireless device is used to generate one of a reference sequence and a scrambling sequence. 13. A method for use in a wireless device of generating a pseudo-random sequence based on information received from a network node, the method comprising:determining a length of a virtual cell index field of downlink control information, DCI, based on a number of configured virtual cell identities, IDs; receiving the DCI from the network node; when the length of the virtual cell index field is greater than zero, generating the pseudo-random sequence based on a virtual cell index contained in the virtual cell index field of the received DCI; and when the number of configured virtual cell IDs is zero, set the length of the virtual cell index field to be of length zero and transmit no virtual cell IDs to the wireless device, thereby causing the wireless device to use a physical layer cell identity to generate a pseudo-random sequence. 14. The method of claim 13 , further comprising receiving the number of configured virtual cell IDs from the network node. 15. The method of claim 14 , further comprising determining whether one of a physical layer cell identity and a virtual cell identity is to be used to generate the pseudo-random sequence, based on the received number of virtual cell IDs. 16. The method of claim 14 , wherein the pseudo-random sequence is one of a reference sequence and a scrambling sequence. 17. The method of claim 13 , wherein an identity of the wireless device is used to generate the pseudo-random sequence. 18. A wireless device configured to generate a pseudo-random sequence based on information received from a network node, the wireless device comprising:a receiver configured to receive downlink control information, DCI, from the network node; and processing circuitry configured to:determine a length of a virtual cell index field of the DCI based on a number of configured virtual cell identities, IDs; when the length of the virtual cell index field is greater than zero, generate the pseudo-random sequence based on a virtual cell index contained in the virtual cell index field of the received DCI; and when the number of configured virtual cell IDs is zero, set the length of the virtual cell index field to be of length zero and transmit no virtual cell IDs to the wireless device, thereby causing the wireless device to use a physical layer cell identity to generate a pseudo-random sequence. 19. The wireless device of claim 18 , wherein the receiver is further configured to receive a number of configured virtual cell IDs from the network node. 20. The wireless device of claim 19 , wherein the processing circuitry is further configured to determine whether one of a physical layer cell identity and a virtual cell identity is to be used to generate the pseudo-random sequence, based on the received number of virtual cell IDs. 21. The wireless device of claim 19 , wherein the pseudo-random sequence is one of a reference sequence and a scrambling sequence. 22. The wireless device of claim 18 , wherein an identity of the wireless device is used to generate the pseudo-random sequence.
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