To remove some further "technical shallowness" :)
the data transfer rate for imode at present is 9.6kbit/sec and
will go up towards 2 Mbit/sec with 3G next year. Of course, these
data rates are the ideal maximum - it does not mean you achieve that
at midnight near Hachiko in Shibuya...
Eurotechnology Japan K. K.
Renfield Kuroda wrote:
> I think an accurate technical explanation is of interest of you guys.
> There seems to be many articles in English mentioning i-mode, but most
> of them are technically shallow and sometimes wrong.
> ** What exactly i-mode is **
> I-mode is an email/web service for cell phone provided by the majority
> share holding cell phone operator in Japan -- NTT DoCoMo. NTT DoCoMo
> has three kinds of nation wide coverage cell phone services -- 800MHz,
> 1.5GHz, and 1.9GHz services. All of these three have their own
> national wide base station networks. The 800MHz service is their
> mainstream service and i-mode is a service option of it.
> As of this writing, there are 9.5 million i-mode subscribers. And now
> all new handsets for the 800MHz service are capable of i-mode service.
> ** I-mode and WAP basically look similar **
> + From content providers' point of view, i-mode handsets as well as
> handsets are regarded as HTTP clients. I-mode contents as well as WAP
> contents are served by ordinary HTTP servers.
> + Handsets themselves don't speak HTTP natively. What handsets talk
> directly to is a gateway. Gateway translates handsets' native
> and HTTP. This is the case both with i-mode and WAP.
> handset ------------------ gateway -------- content servers
> cellular network HTTP
> + Users reach a content they want either by
> + traversing hyper links from a portal
> + using book marked URL
> + entering URL manually
> ** fundamental difference between i-mode and WAP **
> The fundamental difference between i-mode and WAP is markup language
> contents. I-mode employs Compact HTML (cHTML), a subset of HTML 4.0.
> You can get the specification of cHTML from WWW Consortium's web site
> at www.w3.org since it was proposed to the consortium. Whereas WAP
> employs WML (Wireless Markup Language) based on XML. From web
> point of view, WML is just another data format. So there is no hassle
> needed to provide WML contents on an ordinary HTTP server -- just add
> new MIME data type, namely text/WML.
> ** one gateway vs multiple gateways **
> There is only one i-mode gateway, which is operated by NTT DoCoMo.
> Physically, the i-mode gateway is implemented by many machines, and
> DoCoMo will soon start operating 2nd gateway plant. But from
> and users' point of view, there is only one gateway.
> There is no way to change gateways with i-mode handsets. This is also
> the case with the start page. This scheme is inflexible, but the flip
> side is there is no configuration needed for users.
> With WAP handsets, users have to configure their handsets regarding
> where and how to connect to a gateway.
> Actually, this is not always the case. In Japan all WAP phones are
> pre-configured and there is no way to change configuration.
> ** SSL/HTTPS **
> I-mode is capable to handle HTTPS in addition to HTTP. But the
> encryption/description are done on the gateway, not on handsets. The
> next generation of i-mode handsets planned to debut by the end of the
> year would have end to end SSL capability.
> I'm not sure with WAP, but I guess it depends on gateway. Some WAP
> gateways support SSL, but others don't.
> ** packet switched vs circuit switched **
> I-mode is provided on packet switched data connection, not circuit
> switched. Users are charged based on data volume sent and received,
> not time. Whereas there is no packet switched cellular data network
> commercially available now outside Japan.
> In Japan there is a cell phone operator providing a WAP service over a
> packet switched data service.
> -- Binary/unsupported file stripped by Listar --
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> -- Desc: S/MIME Cryptographic Signature
Received on Sat Aug 5 16:03:20 2000