Chapter 6
HSDPA Antenna Selection Techniques
One1 of the main reasons for the slow introduction of Multiple-Input Multiple-Output (MIMO) technologies in commercial wireless systems is the required increment in complexity and hardware cost with respect to traditional, single-antenna systems. While antenna elements are cheap and usually small, each one requires a complete Radio Frequency (RF) chain (low-noise amplifier, frequency downconverter, analog-to-digital converter, filters). Unfortunately, RF hardware is expensive compared with digital hardware, and it does not follow Moore's law [40]. Additionally, the introduction of new hardware implies more energy consumption, which is very inconvenient for today's handheld mobile devices.
On the other hand, simulations of MIMO systems usually assume that individual single-antenna links comprising a full MIMO system suffer from the same average path loss (for example, see [3, 17, 22, 26, 44, 45]). In practice, however, this is rarely observed because realistic scattering environments are highly asymmetrical, especially when differently polarized or orientated antennas are employed. Therefore, a good strategy to extract the diversity gain offered by MIMO systems – while still maintaining the complexity of the system at a reasonable level – consists in selecting the antenna(s) offering the best performance while ...
