CELL BOUNDARY CROSSING IN A UNIDIRECTIONAL SFN FOR HIGH SPEED TRAINS

摘要

A first network node has first antenna nodes located along a track and associated with a first cell. Some of them serve a first cell overlap region that overlaps a second cell overlap region of second antenna nodes connected to a second network node. Some first antenna nodes form downlink beams in a same direction with power levels controlled such that respective amounts of overlap between the downlink beams and respective power levels of the downlink beams jointly cause the first cell's overlap region to emulate a cell border for a user equipment travelling at high speed. Emulated cell border signal power is lower at locations closer to an emulated cell outer edge than at more distant locations. Emulated cell border length is sufficient to cause the travelling user equipment to be within the emulated cell border long enough to successfully perform a handover between the first and second cells.

主权项

1. A method of operating a first network node in a cellular communications network, wherein the first network node is connected to a plurality of first antenna nodes that are located along a track and which provide mobile telecommunications service associated with a first cell, wherein one or more of the first antenna nodes serve an overlap region of the first cell that overlaps an overlap region of a second cell that is associated with a plurality of second antenna nodes that are located along the track and that are connected to a second network node, the method comprising:
causing the one or more first antenna nodes to each form downlink beams in a same direction along the track as one another; controlling transmitter power levels of each of the one or more first antenna nodes such that:
respective amounts of overlap between the downlink beams and respective power levels of the downlink beams jointly cause the overlap region of the first cell to emulate a cell border for a user equipment travelling at or above a known high speed through the overlap region of the first cell, wherein downlink signal power distributed through the emulated cell border is lower at emulated cell border locations closer to an emulated cell outer edge than at emulated cell border locations more distant from the emulated cell outer edge; andthe emulated cell border has a length sufficient to cause the user equipment travelling at the known high speed to be within the emulated cell border for at least a predetermined minimum amount of time necessary to successfully perform a handover of cellular communication service for the user equipment from one of the first and second cells to a different one of the first and second cells.