Entries tagged with “3G” from Paul Lopez Unwired
With a four-way price war going on between AT&T, Verizon,
Sprint and T-Mobile, we have seemed to lost track of VoIP over 3G. Software
from companies such as Fring or Truphone allow you to make VoIP calls on your
iPhone, but only over WiFi. There are hacks (crash-x) that allow you to trick
the iPhone into thinking you're connected to WiFi and make VoIP calls over 3G
(or downspeed to EDGE/GPRS). I'm still wondering ... why bother? If the idea was
to save minutes or money, the carriers have already responded by driving cheap
voice with price reductions. Besides, VoIP over 3G needs massive data compression
and low latency to battle quality of service issues that make the user experience
poor. Skype claims they only need
a small amount of bandwidth - between 6 kbps and 40 kbps, but I don't think
they can overcome latency issues. Many users were disappointed Skype 1.3 did
not include push notifications or support VoIP over 3G. They still have
usability issues using Skype when "real" phone calls come in (it logs you off). Eventually data
plans will race for the bottom too so Skype could become irrelevant on 3G/4G
handsets.
Sprint has announced progress with their mobile WiMAX initiative, Xohm, saying they will have the service available in select cities by Q2'2008. The company is enthusiastic about laptop and tablet PC manufacturers claiming they will have embedded Mobile WiMAX in their next generation machines. Sprint has placed a big bet with WiMax. Despite marketing efforts by Intel and the WiMax Forum, the spectral efficiency and overhead signaling in 802.16e-2005 has disadvantages compared with 4G standards, LTE (Long-Term Evolution) and UMB (Ultra Mobile Broadband).
Improvements in standards are all about spectral efficiency. The 3G and 4G debate places LTE as leading with WiMAX and UMB competing for second place. 4G is characterized by larger channels (up to 20MHz) and uses the popular OFDM modulation scheme. GSM and WCDMA carriers will follow the 3GPP (Third Generation Partnership Project) path to LTE as the 4G standard. UMTS is the dominant 3G standard and now with improvements brought with HSDPA (High Speed Downlink Packet Access) and even HSUPA (uplink), we actually see good broadband performance in the wireless wide area network. The second 3G standard is CDMA EvDO (used by Verizon in the U.S.).
What is confusing for WiMax is that the IEEE is already working on improving the standard called, "IEEE 802.16m," due to be ready by 2010. No one knows if this will be backward compatible with today's WiMax implementations. The advantage of UMB is it is backward compatible with CDMA systems even though there is a dependency on a single supplier of chips - Qualcomm. With WiMax-802.16e becoming commercially available in 2008 and Intel's delivery of chips in laptops; it has a strong head start. Intel was instrumental in establishing the explosion of 802.11 WiFi networking. The big difference here is you are dealing with licensed spectrum where the stakes are much higher than merely establishing a de-facto standard such as WiFi. As Peter Gabriel says, "Too much at stake, ground beneath me shake; and the news is breaking." I hope the monkey doesn't get hurt.
About Paul Lopez
Paul Lopez is a 25-year technology veteran whose career has spanned multiple disciplines such as product management, software development, engineering, marketing, business development and operations... read more
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