The so-called MIMO technology (multiple-input and multiple-output), which may be used in wireless radio frequency telecommunications, relates to the use of multiple send and receive antennas for a wireless communication at for example a base station or a user equipment. The MIMO technology forms the basis for coding methods which use the temporal as well as the spatial dimension for transmitting information enabling therefore a space and time coding. Thus, a quality and data rate of the wireless communication may be increased.
In a so-called massive MIMO system a plurality of user equipments may be arranged within a cell served by a base station having a plurality of antennas. In the massive MIMO system a configuration of individual antenna transceivers of the base station may vary depending on a location of each of the user equipments and transmission conditions in an environment of the base station and the user equipment.
The massive MIMO system may be used in connection with a time division duplex (TDD) system in which a transmission of an information stream between the base station and a user equipment is split up in time slots. Different time slots for uplink (UL) communication and downlink (DL) communication may be provided for communicating information from the user equipment up to the base station and for communicating information from the base station down to the user equipment. For such a combined massive MIMO TDD system there is a need for an additional time slot which may be called “header”. The header is used to send a training signal or training sequence from the user equipment to the base station. Based on the received training sequence, the base station may configure the transceivers of its antenna array. Thus, high antenna gain for the payload transmitted in the following time slots can be achieved. The payload may be transmitted in a number of uplink and downlink time slots. However, when the user equipment is moving, the channel quality may degrade due to a change of the spatial arrangement between the base station and the user equipment. The faster the user equipment is moving, the faster the channel quality may degrade. The channel quality may be measured as a bit error rate (BER). If there are multiple UL/DL slots within one frame, depending on the moving speed of the user equipment, only the first time slots of the frame may be adapted to be used before being degraded significantly by the increased bit error rate. To avoid this problem, the header rate may be increased such that the training sequence is transmitted more frequent. However, this will have impact on the system capacity, especially as all user equipments in the cell and in neighboring cells need to be synchronized.
Therefore, there is a need to improve a data transmission in a massive MIMO system to mitigate deterioration due to mobility of a user equipment.