Uplink synchronization maintenance principles in wireless networks
First Claim
1. A method for maintaining synchronization in a cellular network between a plurality of user equipment (UE) in a cell and a base station (eNB) serving the cell, comprising:
- maintaining synchronization of each UE in the scheduled group with the eNB by sending a timing adjustment (TA) command if needed in response to receiving a scheduled transmission from each respective UE in the scheduled group;
determining a maximum TA rate expected for the cell; and
maintaining synchronization of each UE in the unscheduled group with the eNB by allocating a periodic reference signal (sync-RS) to each UE in the unscheduled group and by sending a respective TA command if needed in response to a respective sync-RS received from each UE in the unscheduled group, wherein the sync-RS period is configured by the eNB to be approximately equal to the inverse of the maximum TA rate expected in the cell.
3 Assignments
0 Petitions
Accused Products
Abstract
A cell within cellular network includes user equipments (UEs) that transmit data to a base station (eNB). UEs are synchronized to the eNB upon entry to the cell. If a particular UE has data to transmit, it will be placed in a connected state and scheduled for transmission. Over a period of time, not all of the UEs will have data to transmit. The UEs are tracked as a scheduled portion and an unscheduled portion, wherein a UE is included in the scheduled portion in response to receiving a scheduling request from the UE. Synchronization is maintained between the eNB and each UE in the scheduled portion by sending a timing adjustment (TA) command if needed in response to receiving a scheduled transmission from each respective UE in the scheduled portion; Synchronization is maintained between the eNB and each UE in the unscheduled portion by allocating a periodic reference signal (sync-RS) to each UE in the unscheduled portion and by sending a respective timing adjustment (TA) command if needed to each respective UE in the unscheduled portion in response to a respective sync-RS received from each UE in the unscheduled portion.
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Citations
22 Claims
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1. A method for maintaining synchronization in a cellular network between a plurality of user equipment (UE) in a cell and a base station (eNB) serving the cell, comprising:
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maintaining synchronization of each UE in the scheduled group with the eNB by sending a timing adjustment (TA) command if needed in response to receiving a scheduled transmission from each respective UE in the scheduled group; determining a maximum TA rate expected for the cell; and maintaining synchronization of each UE in the unscheduled group with the eNB by allocating a periodic reference signal (sync-RS) to each UE in the unscheduled group and by sending a respective TA command if needed in response to a respective sync-RS received from each UE in the unscheduled group, wherein the sync-RS period is configured by the eNB to be approximately equal to the inverse of the maximum TA rate expected in the cell.
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2. A method for maintaining synchronization in a cellular network between a plurality of user equipment (UE) in a cell and a base station (eNB) serving the cell, comprising:
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maintaining synchronization of each UE in the scheduled group with the eNB by sending a timing adjustment (TA) command if needed in response to receiving a scheduled transmission from each respective UE in the scheduled group; determining a maximum TA accuracy targeted in the cell; and maintaining synchronization of each UE in the unscheduled group with the eNB by allocating a periodic reference signal (sync-RS) to each UE in the unscheduled group and by sending a respective TA command if needed in response to a respective sync-RS received from each UE in the unscheduled group, wherein the sync-RS bandwidth is configured by the eNB to be approximately equal to the inverse of the maximum TA accuracy targeted in the cell.
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3. A method for maintaining synchronization in a cellular network between a plurality of user equipment (UE) in a cell and a base station (eNB) serving the cell, comprising:
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maintaining synchronization of each UE in the scheduled group with the eNB by sending a timing adjustment (TA) command if needed in response to receiving a scheduled transmission from each respective UE in the scheduled group; and maintaining synchronization of each UE in the unscheduled group with the eNB by allocating a periodic reference signal (sync-RS) to each UE in the unscheduled group and by sending a respective TA command if needed in response to a respective sync-RS received from each UE in the unscheduled group, wherein each sync-RS is allocated every n sub-frames in a symbol slot not used by a demodulation reference signal (DMRS) or by data transmission. - View Dependent Claims (4, 5, 6)
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7. A method for maintaining synchronization in a cellular network between a plurality of user equipment (UE) in a cell and a base station (eNB) serving the cell, comprising:
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maintaining synchronization of each UE in the scheduled group with the eNB by sending a timing adjustment (TA) command if needed in response to receiving a scheduled transmission from each respective UE in the scheduled group; maintaining synchronization of each UE in the unscheduled group with the eNB by allocating a periodic reference signal (sync-RS) to each UE in the unscheduled group and by sending a respective TA command if needed in response to a respective sync-RS received from each UE in the unscheduled group; transmitting to a UE in the unscheduled group on a downlink (DL) channel; and receiving an autonomous TA request from the UE in the unscheduled group in response to a timing variation beyond a threshold observed by the UE in the DL channel transmission from the eNB. - View Dependent Claims (8, 9, 10)
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11. A method for maintaining synchronization in a cellular network between a plurality of user equipment (UE) in a cell and a base station (eNB) serving the cell, wherein the cellular network is a discrete Fourier Transform (DFT)-spread orthogonal frequency division multiple access (OFDMA) system comprising:
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maintaining synchronization of each UE in the scheduled group with the eNB by sending a timing adjustment (TA) command if needed in response to receiving a scheduled transmission from each respective UE in the scheduled group; and maintaining synchronization of each UE in the unscheduled group with the eNB by allocating a periodic reference signal (sync-RS) to each UE in the unscheduled group and by sending a respective TA command if needed in response to a respective sync-RS received from each UE in the unscheduled group.
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12. A method for maintaining synchronization in a cellular network between a user equipment (UE) in a cell and a base station (eNB) serving the cell, comprising:
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placing the UE in a low power standby mode (DRX) while the UE has no data to transmit or receive; receiving an allocation for a periodic reference signal (sync-RS); transmitting the sync-RS to the eNB periodically while in DRX mode, wherein the sync-RS period is configured by the eNB to be approximately equal to the inverse of the maximum TA rate expected in the cell; receiving a timing adjust (TA) command, if needed, from the eNB in response to the sync-RS; and determining a maximum TA rate expected for the cell. - View Dependent Claims (18, 19)
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13. A method for maintaining synchronization in a cellular network between a user equipment (UE) in a cell and a base station (eNB) serving the cell, comprising:
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placing the UE in a low power standby mode (DRX) while the UE has no data to transmit or receive; receiving an allocation for a periodic reference signal (sync-RS); determining a maximum TA accuracy targeted in the cell; transmitting the sync-RS to the eNB periodically while in DRX mode, wherein the sync-RS bandwidth is configured by the eNB to be approximately equal to the inverse of the maximum TA accuracy targeted in the cell; and receiving a timing adjust (TA) command, if needed, from the eNB in response to the sync-RS.
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14. A method for maintaining synchronization in a cellular network between a plurality of user equipment (UE) in a cell and a base station (eNB) serving the cell, comprising:
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maintaining synchronization of each UE in the scheduled group with the eNB by sending a timing adjustment (TA) command if needed in response to receiving a scheduled transmission from each respective UE in the scheduled group; and maintaining synchronization of each UE in the unscheduled group with the eNB by allocating a periodic reference signal (sync-RS) to each UE in the unscheduled group and by sending a respective TA command if needed in response to a respective sync-RS received from each UE in the unscheduled group, wherein each sync-RS is allocated every n sub-frames in a symbol slot not used by a demodulation reference signal (DMRS) or by data transmission. - View Dependent Claims (15, 16, 17)
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20. A cellular telephone for use in a cellular network, comprising:
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a receiver connected to an antenna operable to receive information from a base station (eNB) within a given cell that provides information via a downlink (DL) channel; a processor connected to a storage memory holding instructions for execution by the processor and coupled to the receiver, wherein the processor is operable to place the cellular telephone in a low power mode (DRX) during which the cellular telephone is not expected to transmit data to the serving eNB, wherein the processor is operable to receive an allocation for a periodic reference signal (sync-RS) via the DL channel; a transmitter coupled to the processor operable to transmit the sync-RS to the eNB periodically while in DRX mode; and wherein the processor is operable to receive via the DL channel a timing adjust (TA) command, if needed, from the eNB in response to the sync-RS.
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21. A user equipment (UE) for use in a cellular network, comprising:
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means for placing the UE in a low power standby mode (DRX) while the UE has no data to transmit or receive; means for receiving an allocation for a periodic reference signal (sync-RS); means for transmitting the sync-RS to a base station (eNB) periodically while in DRX mode; and means for receiving a timing adjust (TA) command, if needed, from the eNB in response to the sync-RS, whereby synchronization is maintained between the UE in a cell and the eNB serving the cell.
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22. A base station apparatus (eNB) for use in a cellular network, comprising:
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a receiver connected to an antenna operable to receive transmissions from user equipment (UE) in a cell served by the eNB; a transmitter coupled to an antenna operable to transmit to the UE served by the eNB; a processor connected to a storage memory holding instructions for execution by the processor and coupled to the receiver and to the transmitter, wherein the processor is operable to track a plurality of UE as a scheduled group and an unscheduled group, wherein a UE is included in the scheduled group in response to receiving a scheduling request from the UE; wherein the processor is operable to maintain synchronization of each UE in the scheduled group with the eNB by sending a timing adjustment (TA) command if needed in response to receiving a scheduled transmission from each respective UE in the scheduled group; and wherein the processor is operable to maintain synchronization of each UE in the unscheduled group with the eNB by allocating a periodic reference signal (sync-RS) to each UE in the unscheduled group and by sending a respective TA command if needed in response to a respective sync-RS received from each UE un the unscheduled group.
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Specification