Multiple-input, single-output (MISO) wireless communications basically mean that the transmitter has multiple antennas, and the receiver has only one.
Wireless channels are very challenging. For instance, they have random deep fades, where the received signal has almost zero power. Under those conditions, there is very little that can be done to keep the data flow going.
One solution to the fading problem is to create diversity: send the signal through multiple channels, hoping that at least one of them is not in a deep fade. In wireless systems, it is possible to create these multiple channels without increasing the bandwidth or the transmit power.
For example, one could have multiple receiver antennas (this would be a SIMO system). Under some conditions, each receiver antenna sees a different channel. The receiver can then combine all the received signals and get a very significant performance improvement.
However, sometimes it is unfeasible to have multiple antennas in the receiver. One example would be the base-station to mobile channel. One would like to have many antennas on the base station, where there is ample space and power, and only one in the receiver, which is very limited.
MISO systems try to create diversity when the transmitter has multiple antennas. This is much more challenging than the SIMO case, because it requires either channel knowledge at the transmitter, or specially designed signals such as the Alamouti space-time code.
I recommend getting "Introduction to Wireless Communications" by R. Heath. It's a very good book, covers all of this material, and is not too expensive.