Beam forming offers the ability for a transmitter to more efficiently use the power available to it by concentrating the power in a beam rather than transmitting using an omni-directional antenna. The use of beams also have the potential advantage of reducing interference to devices which are not the intended recipient in a geographic location by reducing the coverage area into which transmissions are directed.
In order to take advantage of the potential advantages of beams, a transmitter device normally supports one or more beam patterns and chooses to use a beam pattern which is believed to be likely to provide a good communications channel for communicating with an intended transmission recipient.
The decision as to which beam to use to transmit to a target recipient may, and often does, rely on some form of communication from the target recipient which helps the transmitter device decide on what beam to use at a given time. The target device may then monitor for signals on the beam on which it expects to receive signals with other devices potentially being transmitted to using different beams.
Base stations are particularly well suited for using beam forming techniques to form different beams and to transmit on such beams. One reason beam forming approaches work well with base stations is because base stations often have multiple antenna elements which are spaced physically apart from one another or oriented in different directions which facilitates beam forming as compared to cases where antenna elements are physically close to each other which is more likely to be the case on user equipment devices such as cell phones which may be, and often are, handheld devices.
Beam forming solutions are expected to be more commonplace in pre-NR and more so on NR solutions for both mobility and fixed wireless applications.
The triggers for changes in the beam could be a multitude of reasons—ranging from mobility, to the environmental impact on specific frequencies being used. Such changes in the serving beam could be in the order of 100s of micro seconds to tens of milliseconds.
A problem with beam forming is that the transmitting device and receiving, e.g., target device to which a transmission is sent, may have a different understanding as to which beam will be used for the transmission to the receiving device. Such a miss-understanding may be the result of the transmitting device failing to receive a signal from the receiving device indicating that a change to anther beam is to be made, switching by the transmitter and/or receiver in a manner that is not synchronized between the transmitter and receiver, e.g., due to the beam which was being used to communicate being blocked or subject to interference, or for other reasons.
While devices which lose a radio connection due to a miss-understanding at the beam to be used or for other reasons, may trigger a radio connection reestablishment procedure, radio connection reestablishment is often a relatively time consuming processes and may result in the temporary loss of service while the reconnection process takes places. Thus it is desirable if methods could be developed which can support use of beams while minimizing or reducing the risk of having to go through a radio connection re-establishment process when the beam in use is no longer viable or a miss-understanding as to what beam is to be used occurs due to a lost beam change message.