What drives the advancement towards ever faster cellular network speeds?
what is it that makes it possible for cellular networks to keep getting faster
Basically, good old Moore's law.
The handset is only half the equation. More modern and powerful silicon does help in getting better channel quality, less noise, etc. However this can't go above the channel bandwidth as per Mr. Shannon.
A simple way to boost the bandwidth available to each user is therefore to slice the landscape into smaller cells. Directional antennas on top of towers slice the "round" cell into quarters, like an orange.
Installing lots of micro/picocells everywhere in densely populated areas means each base station only handles a smaller number of users. Less users per cell means more bandwidth per user. This is enabled by reducing the price of base station hardware (ie, cheap silicon, Moore's Law, and MMICs which integrate the RF bits on-chip).
A smarter system also helps. For example, in GSM, even when you don't talk, your bandwidth time slot is reserved for you, which is wasteful.
An important thing is also the availability of these at a reasonable price:
- Big FPGAs with truly insane computation power
- Fast ADCs/DACs
- Microwave ICs
These enable digital radio, and this is where the juicy bits are, like MIMO and adaptive antenna arrays with real-time beamforming and channel equalization, advanced (and adaptive) modulations, plus strong error-correction codes which require lots of computing power, etc.
I think following are some of the key technologies/techniques driving up cellular data rates.
Move to higher carrier frequencies where wider bandwidths are available. Soon we will have millimeter wave technology being used in cellular.
Multi Input Multi Output (MIMO) Antenna systems allowing parallel transmission of data streams.
Advance modulation schemes such as OFDM and QAM.
Stronger forward error correction codes not requiring re-transmissions and bringing us ever closer to Shannon Capacity.
Shrinking cell sizes. Now we have the same frequency divided among a smaller number of users.
Assuming the same bandwidth, the only way to boost datarates is better coding: QAM versus GSM's MSK, 16QAM versus QAM, 256QAM versus 16QAM,
And in all this, multipathing and fading must be handled.
With more bits per Hertz, the SignalNoiseRatio (SNR) needs to improve, tho coding provides a one-time 5 or 10 dB assist here. To improve SNR, the link needs more ERP (focused TX antennas), higher-gain receiver antennas (more elements, phased arrays, etc giving more area to gather more energy) and shorter paths to reduce pathloss.