Almost 3 years ago an article in this weblog discussed the relatively small difference in performance between HSPA+ and LTE. Its perplexing to see GSM operators wasting time and money on LTE, when HSPA+ is good enough. Especially when the speed difference between LTE and HSPA+ can be less than a factor of 2. Latency is improved, but VoIP works over HSPA+ fine and there’s a perfectly good 2G network used by most mobile operator customers for voice. The congestion issue is generally on the back-haul not the air interface, and a societal change is upon us where its just plain rude to invite someone to your place (home or work) and not offer WiFi access, and most data hungry devices have WiFi so bypass is alive and well without the need for femtocells.
Recently NSN and Ericsson have demonstrated pre-standards LTE-Advanced and claim deployments will be possible by 2013. The pre-standards version of LTE Advanced demo’ed had a tenfold improvement on current LTE speeds on commercial networks. But this would still leave the new system a few 100 Mbit/s short of the gigabit speeds demanded by the ITU for ‘true 4G’. So perhaps LTE is 3.9G and the current pre-standards LTE Advanced is 3.99G.
The financial analysts really should be questioning the operators they cover on their wireless strategy. To put it in simple terms a financial analyst can understand:
- HSPA+ is available now, if its not deployed already since 2009.
- LTE requires about 7 times the investment of a HSPA+ upgrade (core and access upgrade is required) for a performance gain of up to 2.
- LTE Advanced requires about twice the investment of LTE (this is a guestimate) and has 10 times the performance of LTE and up to 20 times the performance of HSPA+.
If you can wait, do so, as LTE is an interim technology for most GSM operators. Sorry CDMA guys, you’re building out another technology island, looks like the GSM guys really do not want you to join their party just yet. Though when adequate software defined radios finally arrive on the market in perhaps a few more years (always seems to be 2-3 years away from being commercial) these issues all go away.
Perhaps AT&T got it right when they bit the bullet and decided to change out their network from TDMA to GSM back in 2001. And let’s hope TMO can educate AT&T on the cost benefits of HSPA+ which they’ve been happily calling 4G, while AT&T finally focuses on integrating its patchwork quilt of networks and management systems so it finally has A network before jumping on LTE Advanced. But when did common-sense matter when its the shareholder’s money and the financial analysts continue to not be held accountable for their weak coverage.
100% agreed, having been a radio planner for an operator in Africa, I failed to see the business sense in deploying LTE at all. If you stop to consider normal old GSM (2G) augmented with technologies like Ericsson’s VAMOS which allow up to 4 times the capacity with no degradation in voice quality (actually a mild improvement) it is easy to see that voice and sms congestion are not problems that need solving by making huge investments in LTE or even LTE advanced. Looking to the data side, sure 3G networks are congested and can fall over, but quite frankly if you deploy a 3G network with a comprehensive offload strategy in highly congested areas, you can achieve data offload at rates better than LTE or with new WiFI equipment better than LTE advanced today for comparatively negligible capital investment. Couple that to the fact that by doing proper 3G offload you avoid funneling all the data traffic through your core netwrok (SGSN and GGSN) you come out with a winning combination that I think is going to prove a thorn in the side of those punting LTE as the next big thing.
LTE-Advanced is a series of backward-compatible improvements on LTE. It is not a completely new air interface, as it is compared to WCDMA/HSPA. It reaches theoretical peak rates of 3 Gb/s using 8X8 MIMO spatial multiplexing and aggregated channels of up to 100 MHz (by putting together 5 20 MHz channels). In fact, 3GPP Release 8 LTE using 4X4 MIMO in 20 MHz channels reaches peaks of 300 Mb/s, and 8X8 MIMO and 100 MHz yield factors of 2 and 5(=10) times capacity. The point is that there is no real benefit to waiting for LTE-Advanced. Going to LTE-Adv means SW (maybe HW) upgrades and adding more antennas. And besides finding 5 pieces of 20 MHz spectrum all yours ain’t gonna be easy.
Regarding latency me thinks you are underestimating the importance. Effective high TCP/IP bitrates are highly dependent on low latency due to the way congestion control works for TCP. So getting higher peak rates without lowering latency is useless.
LTE/SAE has also many more advantages over HSPA that make the move for operators almost obligatory.
The acid test isn’t technology, its customer experience. And as a customer of both LTE and HSPA+ the difference is minimal. Skype works on both, email attachments finally download in a reasonable time on both, surfing the web works nice in both, YouTube works in both. The technical niceties you mention do not significantly impact my experience. My recommendation remains, if you can, wait for LTE-advanced and then make the investment. This is one investment where being early will not pay dividends, just like IMS.