Month: July 2007

Evolved EDGE: RED, HOT and HUGE

I’ve already reported back in November 2006 that a number of companies in 3GPP are seeking to once again increase the data rates for GPRS beyond what is available with EDGE today. The feature is commonly called evolved-EDGE. At this point in time there seem to be a number of working groups inside 3GPP dealing with the nitty gritty details and they’ve called themselves RED-HOT and HUGE.  Here’s what the abbreviations stand for:

  • RED-HOT: REduced Symbol Duration – higher Order modulation and Turbo coding
  • HUGE: Higher order Uplink performance for GERAN Evolution

Totally obvious… Here’s more on the 3GPP server.

Why Does The iPhone Not Have 3G On Board? – I Don’t Think It’s the Power Consumption

Carlo Longino points out on his blog that Steve Jobs has said battery capacities and immature 3G chipsets that take too much power are the reason the iPhone doesn’t have any 3G capabilities. If you want to build a phone these days that is designed for only being used for a two minute voice call once or twice a week, using a 2G chipsets is surely the right thing to do as standby power consumption is definitely lower than what 3G chipsets can do today. However, the iPhone is a multimedia device and is built for being used throughout the day for a myriad of purposes. Therefore 3G chipset power consumption is the least of your worries.

Compared to what the processor, display, background illumination, camera and memory consume during intensive use during the day, the additional power required for a 3G chipset while in standby is not worth mentioning. Even without a lot of network use my battery on the N93 is flat in the evening when I heavily use my phone during the day for taking pictures, navigating (NokiaMaps), taking notes, checking and responding to eMails, playing games, reading documents, etc. etc. All of this requires little to no network interaction. On days without a lot of activity the battery is still almost full in the evening, despite having been attached to a 3G network all day long. So 3G chipset idle mode power consumption is definitely not an issue if the phone / multimedia device is used heavily during the day.

But once you use the cellular network it doesn’t really matter if you use a 2G or 3G network. In both cases the battery is flat after two to three hours if I use the phone together with a notebook to access the Internet. I don’t think the iPhone is designed to do this but the same is true for using the network with the built in browser.

I wonder if Apple’s decision not to include 3G has more to do with the fact that you can count the number of 3G or 3.5G capable mobile phones (not datacards) in the U.S. on one hand these days. Compare that to Europe where 3G in mobile phones are already mainstream technology. If Apple had been a European company it could well be their decision would have been different.

How Do You Hand Over A 4G Voice Call to 2G?

WiMAX, LTE, UMB, etc. etc., buzz words in the emerging 4G wireless space. Different interests, standardization groups and politics but they all have one thing in common: All are based on IP and all will rely on Voice over IP (VoIP) in one form or another (e.g. IMS or SIP) to carry voice calls. With sheer bandwidth, IP header compression and optimized handover strategies between cells I can imagine it happening. But what happens when you run out of network coverage and only a GSM network is available to continue the call in?

A number of alternatives exist. The first one might be evolved EDGE which could deliver GPRS data rates high enough to sustain a VoIP call begun in a 4G network on the packet switched side of the network. However, I wouldn’t bet on this one happening everywhere. It’s more likely that the VoIP call must be continued in the circuit switched side of the GSM network. But how can that be done?

Voice Call Continuity (VCC) could come to the rescue. A first version is already standardized in 3GPP TS 23.206 and it can do this and many other interesting things. I’ve done a short intro on VCC before, take a look here. Yes, it’s standardized but it’s not a home run:

One of the problems with VCC is that the mobile needs to be connected to both the 4G network and the GSM network at the same time to perform a handover. This consumes more energy then only being connected to one network at a time. Furthermore, such a dual connection might be difficult to establish if the two networks use the same frequency band. If the 4G network is deployed in the 2.5 or 3.5 GHz band then this is not going to be a problem. In case classic 2G frequency bands (850, 900, 1800, 1900 MHz) are partly re-farmed and the GSM network to be handed over to is nearby then VCC will become a challenge. 3GPP Release 8 might yet get a work item to study the possibility of single radio VCC (SR-VCC) to deal with these issues and I am looking forward to see how handover speeds in the order of a few hundred milliseconds can be achieved.

Summary

All-IP wireless networks will be a great thing to have but solving the handover to legacy wireless networks to prevent calls from dropping is going to be a difficult thing.