4.5G – What’s the Big Deal About Half a “G”?

Peter Jarich
Peter Jarich

Summary Bullets:

  • Every wireless technology generation fundamentally evolves before a new one materializes: GSM evolved into GPRS and EDGE, UMTS evolved into HSPA.
  • While LTE-A is an evolution of LTE, it will further evolve (with 3GPP R12/13 features) before we arrive at 5G.
  • The move to “4.5G” is different from previous evolutions, if only because 5G aims to address a more diverse set of requirements.

The concept of a “half-G” isn’t new. GPRS was often referred to as “2.5G,” with EDGE called out as “2.75G.” The same dynamic played out with 3G, and HSPA/HSPA+. It’s not surprising, then, that we’re talking about 4.5G in the run up to 5G deployments. (Note: while the term “4.5G” is being largely used by one specific vendor, we’re using it here more broadly.)

Yet if these previous evolutions suggest that this is simply the way the wireless ecosystem works, there’s a risk of ignoring the importance (and opportunities) of 4.5G.

  • What’s the Point of a Half-G? The cynical among us might think that fractional-G stepping stones are all about marketing – getting new buzz from an existing technology. Looked at another way, they’re about extending the capabilities of a technology before jumping to a completely new generation (with a new architecture and/or air interface), while ensuring backwards compatibility. Of course, where spectrum is doled out for specific technology generations, fractional generations help get the most performance from RF frequency allocations without running afoul of regulators who might not allow existing spectrum to be used for a new technology.
  • What is 4.5G? If this were a multiple choice quiz, potential answers to the preceding question might include: (a) wireless technologies between 4G and 5G; (b) 3GPP R12/13 enhancements to LTE-A; (c) a collection of LTE-A technologies including tighter cellular-WiFi integration, device-to-device communications, massive carrier aggregation, new modulation schemes, and virtualization; (d) all of the above. Those answering with “d” would be correct.
  • Is this Half-G Any Different? The move to 3G was largely about delivering a better mobile data performance. 4G delivered greater improvements and the move to IP networking. 5G, however, comes with a much broader set of requirements. It’s about data rate and spectral efficiency improvements, but also latency improvements, network density improvements, and accommodating IoT use cases with low-speed solutions and battery life improvements. This will require a diverse set of technologies. The requirements that get commercialized as part of 4.5G, then, will depend on vendor assets, operator priorities, and expectations of what what’s commercially feasible in the near-term. In other words, this half-G is much more up for grabs than any in the past.
  • What is a Half-G Really Worth? The implication of the last point is pretty clear. Vendors planning to benefit from LTE-A evolutions need to message its value – if only to drive operator thinking around the technologies they’re in a position to develop. However, there’s another reason for everyone to care; a lot of money is on the table. As operators plan for how to evolve their LTE and LTE-A networks, they’ll have to think about the timing of 5G vs. 4.5G. Do they want to wait until 5G features and technologies are fully baked or move on upgrades earlier? It’s not a completely either/or question; many foundational network investments will feed into tomorrow’s 4.5G and even 5G futures. Regardless, if 5G is positioned as a major break, operators will need to understand why they can’t afford to wait for it.

Leave a Reply