# US 11,444,745 B2 · Coordination of duplex directions in NR TDD system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,444,745 B2 - Document ID: US11444745B2 - Status: Granted - Kind: B2 - Application number: 16/476,855 - Filed: 2018-01-09 - Published: 2019-11-28 - Granted: 2022-09-13 - Earliest claimed: 2017-01-09 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget Lm Ericsson (Publ) - Inventors: Du Ho Kang; Jung-Fu Cheng; Havish Koorapaty; Sorour Falahati - Web page: https://patentgrep.com/patent/US11444745B2 ## CPC - H04L 5/1469: {using time-sharing} - H04L 5/16: Half-duplex systems; Simplex/duplex switching; Transmission of break signals {non-automatically inverting the direction of transmission} - H04W 24/02: Arrangements for optimising operational condition - H04W 28/18: Negotiating wireless communication parameters - H04W 72/0446: Resources in time domain, e.g. slots or frames - H04W 72/29: between an access point and the access point controlling device - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A method performed in a system comprising a joint traffic direction scheduler configured to coordinate time-division-duplexing (TDD) transmissions for multiple cells comprises obtaining TDD operation information from each of the cells, determining, based on the obtained TDD operation information, a transmission direction to be used by each of the cells during one or more transmission time intervals (TTIs), and indicating to the cells the determined transmission direction. ## Claims ### Claim 1 A method performed by a joint traffic direction scheduler of a base station configured to coordinate time-division-duplexing (TDD) transmissions to be performed by multiple cells of a coordination group, the method comprising: obtaining, by the joint traffic direction scheduler, TDD operation information from each cell of the multiple cells in the coordination group; determining, by the joint traffic direction scheduler and based on the obtained TDD operation information, a transmission direction to be used by each cell during an upcoming period of time including one or more transmission time intervals (TTIs) of each cell; and indicating, by the joint traffic direction scheduler, to each cell the determined transmission direction to be used by that cell during the one or more TTIs. ### Claim 2 (depends on 1) The method of claim 1, wherein indicating the determined transmission direction comprises signaling that one or more predetermined TDD modes is to be used or is not to be used by one or more of the multiple cells. ### Claim 3 (depends on 2) The method of claim 2, wherein the one or more predetermined TDD modes indicates a predetermined ratio of downlink-to-uplink (DL:UL) transmissions to be used by the one or more of the multiple cells. ### Claim 4 (depends on 2) The method of claim 2, wherein the one or more predetermined TDD modes comprises: a fully dynamic TDD mode; or a hybrid dynamic TDD mode in which a scheduling restriction is imposed within a part of dynamic TDD duration. ### Claim 5 (depends on 2) The method of claim 2, further comprising signaling a duration of the one or more predetermined TDD modes. ### Claim 6 (depends on 1) The method of claim 1, wherein indicating the determined transmission direction comprises signaling that a predetermined TDD mode is to start or stop. ### Claim 7 (depends on 6) The method of claim 6, further comprising configuring the predetermined TDD mode independent of the signaling that the predetermined TDD mode is to start or stop. ### Claim 8 (depends on 1) The method of claim 1, wherein indicating the determined transmission direction comprises transmitting a bitmap for a set of upcoming TTIs indicating a transmission direction to be used by each the cells for each TTI. ### Claim 9 (depends on 1) The method of claim 1, further comprising one or more of the cells determining scheduling details for its own operation during the one or more TTIs, wherein the scheduling details include one or more user equipments (UEs) to be scheduled and a modulation and coding scheme to be used. ### Claim 10 (depends on 1) The method of claim 1, further comprising one or more of the cells switching from a current time-division-duplex (TDD) mode to a new TDD mode based on the indication. ### Claim 11 (depends on 1) The method of claim 1, further comprising controlling the multiple cells to switch between a dynamic time-division-duplexing (TDD) mode and a static TDD mode, comprising: determining a direction of traffic to be scheduled for each of the multiple cells during one or more TTIs; in response to determining that the direction of the traffic is the same for each of the multiple cells during the one or more TTIs, controlling the multiple cells to operate according to a dynamic TDD mode; and in response to determining that the direction of the traffic is not the same for each of the multiple cells during the one or more TTIs, controlling the multiple cells to operate according to a static TDD mode. ### Claim 12 (depends on 11) The method of claim 11, further comprising configuring the static TDD mode for each of the multiple cells according to a fixed downlink-to-uplink (DL:UL) ratio. ### Claim 13 (depends on 12) The method of claim 12, further comprising adjusting the DL:UL ratio according to long-term traffic characteristics of a wireless communication network. ### Claim 14 A base station comprising a joint traffic direction scheduler configured to coordinate time-division-duplexing (TDD) transmissions to be performed by multiple cells of a coordination group, comprising: processing circuitry, memory, and at least one transceiver collectively configured to: obtain, by the processing circuitry of the joint traffic direction schedular, TDD operation information from each cell of the multiple cells of the coordination group; determine, by the processing circuitry and based on the obtained TDD operation information, a transmission direction to be used by each cell during one or more transmission time intervals (TTIs); and indicate, by the processing circuitry, to each cell the determined transmission direction to be used during the one or more TTIs. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein determining the transmission direction to be used by each of the cells during the one or more TTIs comprises one or more of: detecting a buffer status change for one or more of the cells; detecting a buffer status for one or more of the cells; detecting a change of a ratio of downlink-to-uplink (DL:UL) traffic in one or more buffers; and detecting a change of a quality of service (QoS) type to be applied to traffic associated with one or more of the cells. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein determining the transmission direction comprises detecting the buffer status change, and detecting the buffer status change comprises: receiving a periodic or event-based report; and determining whether one or more of the cells have upcoming traffic for both uplink (UL) and downlink (DL) directions. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein determining the transmission direction comprises detecting the change of the ratio of downlink-to-uplink traffic, and wherein the processing circuitry, memory, and at least one transceiver are further collectively configured to switch one or more TDD modes in response to the ratio crossing a threshold. ### Claim 18 (depends on 14) The apparatus of claim 14, wherein the processing circuitry, memory, and at least one transceiver are further collectively configured to send a first mode selection signal to the cells to trigger the use of a dynamic TDD mode when all of the cells are to transmit data in the same TDD traffic direction during the one or more TTIs, else send a second mode selection signal to the cells to trigger the use of a static TDD mode when not all of the cells are to transmit data in the same TDD traffic direction during the one or more TTIs. ### Claim 19 (depends on 14) The apparatus of claim 14, wherein the processing circuitry, memory, and at least one transceiver are further collectively configured to control the multiple cells to switch between a dynamic time-division-duplexing (TDD) mode and a static TDD mode, comprising: determining a direction of traffic to be scheduled for each of the multiple cells during one or more TTIs; in response to determining that the direction of the traffic is the same for each of the multiple cells during the one or more TTIs, controlling the multiple cells to operate according to a dynamic TDD mode; and in response to determining that the direction of the traffic is not the same for each of the multiple cells during the one or more TTIs, controlling the multiple cells to operate according to a static TDD mode. ### Claim 20 (depends on 19) The apparatus of claim 19, wherein the processing circuitry, memory, and at least one transceiver are further collectively configured to configure the static TDD mode for each of the multiple cells according to a fixed downlink-to-uplink (DL:UL) ratio.