With the introduction of smart phones and tablets, mobile data transmission has grown dramatically over the last five years. The Long Term Evolution (LTE) standard improves spectrum utilization efficiency, increases speed, and handles greater data traffic. Success of LTE technology is tied to an ecosystem development that must take place at the same pace—or faster—than that of the infrastructure implementation.
Due to an expected explosive growth of data usage, it has become imperative for operators to make effective use of spectrum and implement LTE as quickly as possible with an ever-increasing number of bands. This is a challenge for transceivers. The 3rd Generation Partnership Project (3GPP) has responded by coming up with a unified approach to FDD and TDD technologies. Currently, the wireless communication spectrum (up to 3.8 GHz) is separated into 43 bands; bands 1 to 32 are classified as LTE-FDD and bands 33 to 43 are classified as LTE-TDD.
From a transceiver standpoint the challenges are:
- Multiband: such a plethora of LTE bands necessitates a multiband transceiver.
- Multimode: roaming requirements in legacy operating networks (WCDMA, EVDO, TD-SCDMA, CDMA and GSM) require transceivers to be multimode.
- Dual technology: transceivers need to support both TDD and FDD technologies.
Transceivers for 0.7 to 2.7 GHz spectrum need to handle both FDD and TDD technologies in order to cover FDD bands 1-32 and TDD bands 33-41. Currently available state-of-the-art transceivers support all of the above bands with multiple ports available from a single RFIC (see Figure 1). This requires significant processing power. In the case of the Fujitsu RFIC shown in the figure, the processing requirement is addressed by distributing the load between the baseband and transceiver. For example, the transceivers are embedded with ARM® processors that reduce baseband processing requirements. This, in turn, reduces power consumption and improves response time for dynamic adjustments.
In addition to being multimode and multiband, today’s multi-featured RF transceivers