After spending an afternoon sitting in the Jerusalem City Center, surfing the net via a FREE municipally provided WiFi internet connection. I have come to the conclusiong that WiFi ( or later WiMX or whatever if goes to ) become the wireless standard beyond its original real plan. Why wouldn't cell phone move away from cellular, GSM, CDMA etc and into WiFi? Why don't they simply halt at least the data expansion of UMTS, put WiFi into the phones, provide a very fast internet data connection to the phone with a later plan to transition fully into WiFi and then even the called end up being VoIP calls? Looks like some of this is actually happening....... stay tuned......
A great articla from Wireless Week
Dual cellular/Wi-Fi schemes face dual handoff, powering issues.
By Karen BrownJanuary 1, 2005Wireless Week© 2005, Reed Business Information, a division of Reed Elsevier Inc. All Rights Reserved.
The classic B-52's song declared "Roam if you want to," and that is the ultimate goal behind developing technology that melds cellular and Wi-Fi local area network connections on one handset.
But it looks like getting there will be a fairly long trip, filled with complex technical and strategic decisions governing when and if a call should be switched from one network to the other, and how to handle the increased power output needed to keep the Wi-Fi antenna active. Still, there are some early indications as to which direction the technology is taking.
Early on, many products are using an "either-or" strategy for their dual cellular/Wi-Fi connections. That is the case for NTT DoCoMo, which rolled out the NEC N900iL handset in November. While it sports radios that can tap DoCoMO's FOMA GSM and an enterprise WLAN, Wi-Fi LAN, it can't roam between the two.
"There is no handover," notes Susumu Takeuchi, DoCoMo's vice president of corporate communications in the United States. "If your call is on the FOMA, you cannot hand off to the LAN network. That isn't possible."
Similarly, Nokia's 9500 Communicator offers a data-only Wi-Fi element, and it also does not possess the ability to shift a data stream from one network to another while the transmission is in progress, according to Dan McDonald, director of marketing for Nokia's enterprise solutions. Instead, the handset has the ability to switch radios and retransmit the data if the handset strays out of Wi-Fi network range.
That may not create a huge problem for users who want to send an e-mail, but with plans to add IP voice capability to future dual-mode, such handoff capability will be important, McDonald notes. "It will be a burden for people who want to continue that conference call in the car on the way home, dropping calls and re-establishing. That will limit adoption. This has to be solved."
Even if roaming is possible, though, it may not always be preferable. In the case of a cellular call in progress, it may not make sense to automatically switch it to a Wi-Fi connection, McDonald points out.
"This switching of calls – it all sounds interesting and romantic, but it's kind of silly to go through all that trouble for a call that has already been established," he says. In addition, users may not want to switch networks if the Wi-Fi connection is in an unsecured public hot spot.
In contrast, it may be vital in the reverse scenario, where a person is talking on a Wi-Fi connection and walks out of the network area. In that case, the handset would have to either drop or have the ability to handoff to the cellular network.
"You can demonstrate that now in the lab environment, but again, the setup has to be so tuned and so consistent a recipe that it won't be generally available to people for a couple of years," McDonald says.
TRIO's SOLUTION The trio of Motorola, Avaya and Proxim, however, say they have cracked that problem. Combining Avaya base stations and network gateways, the Motorola CN 620 handset and Proxim silicon, the three have produced what may be the first IP system that can hand off voice and data signals between Wi-Fi and cellular networks.
The joint offering, dubbed the Seamless Communications Solution, will be marketed by Avaya and is now in field trials. The Seamless Communications Solution system can shift calls from one network to another, automatically setting up a second, parallel call if it detects the call signal is weakening.
"So as I walk away from the building and the signal gets weaker, the phone will decide when it should start to launch an independent call through the wireless PSTN, and when it decides [the signal] is weak enough, it will just hand over," says Frank LoVasco, Avaya's senior manager for mobility. "It's a make before break kind of technology."
One of the trickiest problems to solve with such roaming technology is choosing when to switch network connections – particularly if a user is walking down a street in a commercial area where there are several hot spot outlets. Motorola's answer is to limit the Wi-Fi connection to only the user's home campus. In that way, the phone doesn't face a decision of whether to tap into nearby hot spots as the user walks.
It also can distinguish between its own company access point and Seamless Communications Solution access points run by other companies.
"When we are in the GSM world, the phone is basically GSM only, so it is not necessarily looking for an antenna," explains Bob Duerr, director of product marketing for the Enterprise Seamless Mobility Group. It does periodically wake up to scan for antennas, "but what it is looking for is some very specific signaling from some very specific access points. So if it doesn't see those access points, it simply goes right back to sleep."
That strategy is finding favor among enterprise customers as an acceptable tradeoff between security and cost of cellular minutes. "We originally thought that the enterprises would want people to be able to come in from these hot spots to cut down on their cell minutes," Duerr notes. "And we're finding they don't because of the security issues of coming in from a public spot through a firewall."
POWERING ON Limiting the Wi-Fi connection also is a strategy in dealing with another vexing problem: battery drain. Wi-Fi was not originally developed as a mobile technology using battery-powered devices, so it needs some fancy engineering footwork to meet its power requirements on a mobile handset.
Motorola's CN 620 has the standard cellular battery and offers between 150 and 190 minutes of continuous talk time. Unlike some other early hybrid Wi-Fi handsets, the CN 620 includes proprietary technology that cuts down the power drain of an active antenna. If a handset is communicating with a Wi-Fi base station, for example, its GSM antenna is powered down.
"Unlike some phones where they are constantly looking for antennas and some of the dual-mode phones we suspect where you can't turn the antennas off … some of the proprietary technology we have inside there has really curtailed a lot of that," Duerr says. "The phone becomes very, very intelligent inside the network because it knows what it is talking to."
In the office, the handset can be placed in a standard cradle charger that also has a place for an extra battery. A USB cable can plug into a desktop PC and provide charging as well as actively synching with a computer's Microsoft Exchange or Outlook applications.
Other dual-mode Wi-Fi and cellular products use similar strategies.
TIME FOR TALK But talk time still is an issue for these devices. The NEC handset offers standby power dual mode of 150 hours, with continuous talk time on the FOMA network totaling 140 minutes and on the WLAN 160 minutes. That's short of the average 240 to 300 minutes now offered on many cell phones.
Nokia's McDonald acknowledges that putting a Wi-Fi radio into a mobile handset does come with a powering challenge. He says most Wi-Fi-enabled devices allow only three to four hours of use.
"Wi-Fi is something that does draw battery power more so than cellular," he says. But he adds with Nokia's work in power management, "there are all kinds of technological tricks that are played – in your transmission power you only use what you absolutely have to, et cetera. The Holy Grail here is to ultimately have a full day of power in your hand. It's eight hours of power in your hand that you will have to work with without recharging. That's the ultimate goal."
Device size limits will curb the size of the battery, but McDonald notes an operating system such as Nokia-backed Symbian that has been designed for wireless systems "is very, very power-stingy."
If history is any guide, engineers will develop powering schemes that will extend the handset talk time and allow for more handoffs between Wi-Fi and cellular networks. The primary driver is the value of a product that can offer a business user a single phone wherever they are.
"People should be intrigued by the possibility, and the innovation in this area will be very robust now for the next couple of years, with a lot of investment in this area and a lot of venture capital, because there is some value here," McDonald says.
Although this unified phone technology may be in its toddler stage, it may quickly develop the legs to roam into wider enterprise applications.