802.11b reachability limits is not really a distance thing ,but how much transmitted power can be seen by the receiver above the noise out there. I have a customer where we put two 800m point-to-point 802.11b links in place that carry data and VoIP trunks. To achieve this we used Yagi antennas with 12db gain. Parabolics on high towers can probably reach 10 - 20 km. Of course you're not going to have a yagi or parabolic on your mobile wi-fi phone.
Any wi-fi based mobile service (say for in a campus) will need to have blanket of wi-fi pico cells to cover the required area. You might have these as small as 30-50m radius to ensure that too many users can't use the same bandwidth. The phone will then roam between access points as you move around. (The alternative is a hybrid 802.11b and say GSM, but I have no idea if there is product out there can roam between the two "in call"). This is no different to campus /building wi-fi data installations today - except that voice calls clearly are going to be far more intolerant to the occasional lost frame. Very good RF surveys and design would probably be needed to make sure you have a viable service. Regards, Martin Martin Visser ,CISSP Network and Security Consultant Technology & Infrastructure - Consulting & Integration HP Services 3 Richardson Place North Ryde, Sydney NSW 2113, Australia Phone: +61-2-9022-1670��� Mobile: +61-411-254-513 Fax: +61-2-9022-1800���� E-mail: martin.visserAThp.com > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Richard Hayes > Sent: Thursday, 15 April 2004 10:52 AM > To: [EMAIL PROTECTED] > Subject: [SLUG] [OT] Wireless VoIP > > Dear List, > > On Slashdot today there was an article on Locust SIP switching boxes. > > They are using 802.11 wireless does that mean the wireless > nodes are limited to 300 metres? > > http://locustworld.com/modules.php?op=modload&name=News&file=a > rticle&sid=46&mode=thread&order=0&thold=0 > -- > Richard Hayes > Nada Marketing > 2/713 Pacific Hwy Gordon Australia 2072 > Phone:+(61-2) 9418 4545 Fax:+(61-2) 9418 4348 Mob:+(61) 0414 > 618 425 http://www.nada.com.au > > -- > SLUG - Sydney Linux User's Group Mailing List - > http://slug.org.au/ Subscription info and FAQs: > http://slug.org.au/faq/mailinglists.html > > -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
