Yes, you are right the Full Rate GSM codec operates at 13k. The bearer over the air is still 22k though.
The AMR codec used for GSM and 3G networks is even more efficient, and can dynamically adjust the bitrate, and can operate on an 11k Half Rate bearer. It is also standardised as a code for use over the Internet by (I believe) the IETF.
Where every Cisco VoIP system falls down is on the ammount of bandwidth required to support VoIP. From a telco operator perspective (voice or data) your greatest operational expendature is your bandwidth. Using IP or SIP costs you far more in bandwidth than is economic (when compared to alternatives).
Yes you can multiplex voice and data but that takes even more bandwidth than doing it seperately!
GSM is probably the most efficient way to carry voice over a digital channel. Does very well at 22kbit/sec. You even can do voice over GPRS at 33kbit/sec (the latency sucks, but you can do it). But try running a SIP session and it simply doesn't work. The protocol to establish the session and the overhead cannot be done on a low bandwidth channel.
VoIP makes sence only when bandwith is free, but in the real world it isn't and the commercial imperative is to make the most of it.
Any receiver can be detected. In the UK they listen out for TV's to fine anyone who doesn't have a licence.
The easiest way to find one is to use something called a dip oscillator. Basically if you are receiving an RF signal you are resonating with it, and sucking power. If you, the detector, are radiating a signal at the frequency the receiver is operating and measuring your power output you can tell if someone is receiving the signal.
Also used in WWII to winkle out the spys.
... the SMSC vendor, also how the SMSC are arranged.
Networks with only one SMSC can experience overload on Mobile Originated (MO) SMS. More commonly the problem is actually Mobile Terminated (MT) SMS as the SMSC needs to query the HLR while keeping the handle on the SMS 'open'. A large number of 'open' MT SMS can easily fill the agailable memory on an SMSC. Theis problem is exacerbated with bulk SMS and SMS submitted to the SMSC via an X.25 or IP conenction from an information server.
Networks usually have several SMSC, one to deal with MO SMS and several to deal with MT.
...then Amazon UK will have an English release on 20 February. Should be the same cut as the French version, called "Le Voyage de Chihiro", but with an English box.
I'll guess no red-tint either.
if Sendo engineers can actually integrate onto a Series 60 platform.
Just because the OS can't do what you need, then just bypass it. A classic example of this is SIM Locking to a particular network, or group of networks. The SDK (Pocket PC 2002 and Smartphone) doesn't support this. Sendo complain, HTC, MiTac, Samsung, and Compal work around it (to varying degrees of success).
No record of them on the FCC web site, so they haven't submitted ANY certification information for the 900/1900 version.
Won't be available any time soon then.
Mobile phones themselves are not the things causing interference to the aircraft systems. It is those flashing antenna LED's (with the emphasis on D for Diode). Put a diode on a GSM antenna and you get powerful AM harmonics. The second and third harmonics of GSM900 phones fall right into the ground to air frequency band and can also interfere with aircraft navigation systems.
So either shield the aircraft systems, increasing cost and weight, or ban them all phones just in case someone on the flight has a novelty antenna.
Also if you have a user at the edge of the cell who is having difficulty in being heard the bitrate of all the other users in the cell will also fall. (Near/Far Effect)
Also as users move around the cell the cell radius also changes, so cell areas need to be very small in order to match the customers' expectation of coverage, which is more in the traditional mould of fixed cell sizes rather than today I have coverage, tomorrow I don't.
Also if one power user requests all the bandwidth available it will bump off other users, or degrade everyone else down to accommodate this user, (dependant on the vendors' algorithm admittedly)
Basically a very poor user experience all round, especially if they have to pay a high premium for a new handset that offsets all the handset vendors development costs.
However, if you fix the mobiles in one place, and limit the bandwidth (ie take all the mobility out of it) 3G could be viable.
The BIG downside to these techniques is cost. At least one network in the UK have said "no more 2G cell sites" due to cost and finite return on 2G.
That does leave 3G antenna to mount, however they will tend to be at building level, not above and a cleaver paint job can make the antenna nearly indistinguishable from the brickwork, or concrete, behind it.
Two tins of paint are 100 to 1000 times cheaper.
Many GSM manufacturers and US operators are lobying teh FCC for more spectrum as we speak. Unfortunatly, guess who is using the spectrum?
"I can't tell you who is using that band, National Security"
But you can squese a GPRS only (no voice) network into the very small frequency bands available in the USA. Can't do GSM voice as teh inter cell interference is too high, but you can just about manage it with Coding Scheme 1 in GPRS. Your throughput will only be around 9kbps, but if you want faster write to the FCC and ask for more spectrum.
Used to see this problem at airports with mobile phone networks trying to attract foreign (or alien if you are in the US) roaming customers.
Each network would be belting out higher power than the others, with the total for four or five networks easily higher that the maximum RF fields permitted.
They solved this escalation problem by reading the standards and finding out that in a well specified system, like GSM, the mobile should randomly pick a signal if they are over a certain strength (unfortunately this is a greatly simplified view and why most telco's got it wrong and started a power war).
The same principals for mobile network selection were ported to CDMA systems in the US, so I presume it would also work with 802.11 if they had read any of the other telecommunications standards out there at the time.
Apologies to any people involved in 802.11 standardisation, but this is how it seems to me.
Selling expensive servers to carriers and taking a loss on the handsets is SO 90's. It is a badly flawed business model and carriers are simply not biteing.
It means that corporate integration becomes nigh on impossible, as they don't trust carriers to provide their mobile connectivity if the same server carries their competitors info too. Also server less devices will be coming out, based on Pocket PC or BREW or Java, that have all the advantages of a Danger hiptop or RIM device and none of the ties to the servers.
By default on the Region 2 disc lines in Elvish appear in subtitles. Unfortunately they seem to be anti-alised and are nearly unreadable.
I'd have expected a bit more quality control, especially as the full subtitles are OK.
I'd guess around the 2 second mark for the round trip.
In GPRS it was the biggest shock that the rtt was over 4 seconds in the first release. After many optimisations and very cleaver stuff from the radio vendors we got it down to about 1.4s, very close to the theoretical minimum.
The delay is principally in establishing the packet connection, both in the uplink and downlink as they have to be done seperately.
CDMA2000 is different, but you WILL be surprised by how crap the latency is. Even at >56k it is a long thin network. TCP just never gets out of slow start.
Actually it's not. The manufacturers have a difficult enough time making them all unique. The reason that European operators haven't used EIR before to disable stolen or reprogrammed phones is that turning off one may actually turn off hundreds. All manufacturers are guilty of this, but most are getting better at quality control and old phones are churning out of the market. That's the only technical reason EIR are being considered.
The future is NOT IP telephony. Cellular carriers have already got exactly enough bandwidth in the ground to carry their cellular traffic, both 2, 2.5 and 3G. Bandwidth is expensive. VoIP only makes sense if you have infinite amounts of bandwidth, or if you believe the Cisco BS, which is about the same thing. The latency and packet delay will kill VoIP if used on a carrier scale as the bandwidth requirements are uneconomic, or if are interfacing with a cellular network for the same reason. They need to look for something else to save them. It won't be 3G either.
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Yes, you are right the Full Rate GSM codec operates at 13k. The bearer over the air is still 22k though. The AMR codec used for GSM and 3G networks is even more efficient, and can dynamically adjust the bitrate, and can operate on an 11k Half Rate bearer. It is also standardised as a code for use over the Internet by (I believe) the IETF.
Where every Cisco VoIP system falls down is on the ammount of bandwidth required to support VoIP. From a telco operator perspective (voice or data) your greatest operational expendature is your bandwidth. Using IP or SIP costs you far more in bandwidth than is economic (when compared to alternatives). Yes you can multiplex voice and data but that takes even more bandwidth than doing it seperately! GSM is probably the most efficient way to carry voice over a digital channel. Does very well at 22kbit/sec. You even can do voice over GPRS at 33kbit/sec (the latency sucks, but you can do it). But try running a SIP session and it simply doesn't work. The protocol to establish the session and the overhead cannot be done on a low bandwidth channel. VoIP makes sence only when bandwith is free, but in the real world it isn't and the commercial imperative is to make the most of it.
Any receiver can be detected. In the UK they listen out for TV's to fine anyone who doesn't have a licence.
The easiest way to find one is to use something called a dip oscillator. Basically if you are receiving an RF signal you are resonating with it, and sucking power. If you, the detector, are radiating a signal at the frequency the receiver is operating and measuring your power output you can tell if someone is receiving the signal.
Also used in WWII to winkle out the spys.
They already do. Some car parking places in London cost more than twice the average income per hour...
Cryptome
Knowing Nokia they will probably make it comaptible to HSCSD and not GPRS (like the 9210i)
... the SMSC vendor, also how the SMSC are arranged.
Networks with only one SMSC can experience overload on Mobile Originated (MO) SMS. More commonly the problem is actually Mobile Terminated (MT) SMS as the SMSC needs to query the HLR while keeping the handle on the SMS 'open'. A large number of 'open' MT SMS can easily fill the agailable memory on an SMSC. Theis problem is exacerbated with bulk SMS and SMS submitted to the SMSC via an X.25 or IP conenction from an information server.
Networks usually have several SMSC, one to deal with MO SMS and several to deal with MT.
I'll guess no red-tint either.
Spitired Away
if Sendo engineers can actually integrate onto a Series 60 platform.
Just because the OS can't do what you need, then just bypass it. A classic example of this is SIM Locking to a particular network, or group of networks. The SDK (Pocket PC 2002 and Smartphone) doesn't support this. Sendo complain, HTC, MiTac, Samsung, and Compal work around it (to varying degrees of success).
No record of them on the FCC web site, so they haven't submitted ANY certification information for the 900/1900 version.
Won't be available any time soon then.
the Foundation series gets turned into a Star Wars type space opera.
Think about it? What epic, multi-movie series can the other studios latch onto?
So either shield the aircraft systems, increasing cost and weight, or ban them all phones just in case someone on the flight has a novelty antenna.
Also as users move around the cell the cell radius also changes, so cell areas need to be very small in order to match the customers' expectation of coverage, which is more in the traditional mould of fixed cell sizes rather than today I have coverage, tomorrow I don't.
Also if one power user requests all the bandwidth available it will bump off other users, or degrade everyone else down to accommodate this user, (dependant on the vendors' algorithm admittedly)
Basically a very poor user experience all round, especially if they have to pay a high premium for a new handset that offsets all the handset vendors development costs.
However, if you fix the mobiles in one place, and limit the bandwidth (ie take all the mobility out of it) 3G could be viable.
It was on the BBC and had two series.
http://www.open2.net/science/roughscience/
The BIG downside to these techniques is cost. At least one network in the UK have said "no more 2G cell sites" due to cost and finite return on 2G.
That does leave 3G antenna to mount, however they will tend to be at building level, not above and a cleaver paint job can make the antenna nearly indistinguishable from the brickwork, or concrete, behind it.
Two tins of paint are 100 to 1000 times cheaper.
Many GSM manufacturers and US operators are lobying teh FCC for more spectrum as we speak. Unfortunatly, guess who is using the spectrum? "I can't tell you who is using that band, National Security"
But you can squese a GPRS only (no voice) network into the very small frequency bands available in the USA. Can't do GSM voice as teh inter cell interference is too high, but you can just about manage it with Coding Scheme 1 in GPRS. Your throughput will only be around 9kbps, but if you want faster write to the FCC and ask for more spectrum.
The FCC have already approved a disposable CDMA phone.
Each network would be belting out higher power than the others, with the total for four or five networks easily higher that the maximum RF fields permitted.
They solved this escalation problem by reading the standards and finding out that in a well specified system, like GSM, the mobile should randomly pick a signal if they are over a certain strength (unfortunately this is a greatly simplified view and why most telco's got it wrong and started a power war).
The same principals for mobile network selection were ported to CDMA systems in the US, so I presume it would also work with 802.11 if they had read any of the other telecommunications standards out there at the time.
Apologies to any people involved in 802.11 standardisation, but this is how it seems to me.
If you think 3G (and I don't class 1xRTT as 3G) will be working and a viable commercial business in 6 months you are very much mistaken.
Selling expensive servers to carriers and taking a loss on the handsets is SO 90's. It is a badly flawed business model and carriers are simply not biteing.
It means that corporate integration becomes nigh on impossible, as they don't trust carriers to provide their mobile connectivity if the same server carries their competitors info too. Also server less devices will be coming out, based on Pocket PC or BREW or Java, that have all the advantages of a Danger hiptop or RIM device and none of the ties to the servers.
By default on the Region 2 disc lines in Elvish appear in subtitles. Unfortunately they seem to be anti-alised and are nearly unreadable.
I'd have expected a bit more quality control, especially as the full subtitles are OK.
In GPRS it was the biggest shock that the rtt was over 4 seconds in the first release. After many optimisations and very cleaver stuff from the radio vendors we got it down to about 1.4s, very close to the theoretical minimum.
The delay is principally in establishing the packet connection, both in the uplink and downlink as they have to be done seperately.
CDMA2000 is different, but you WILL be surprised by how crap the latency is. Even at >56k it is a long thin network. TCP just never gets out of slow start.
Actually it's not. The manufacturers have a difficult enough time making them all unique.
The reason that European operators haven't used EIR before to disable stolen or reprogrammed phones is that turning off one may actually turn off hundreds. All manufacturers are guilty of this, but most are getting better at quality control and old phones are churning out of the market. That's the only technical reason EIR are being considered.
The future is NOT IP telephony.
Cellular carriers have already got exactly enough bandwidth in the ground to carry their cellular traffic, both 2, 2.5 and 3G. Bandwidth is expensive.
VoIP only makes sense if you have infinite amounts of bandwidth, or if you believe the Cisco BS, which is about the same thing. The latency and packet delay will kill VoIP if used on a carrier scale as the bandwidth requirements are uneconomic, or if are interfacing with a cellular network for the same reason.
They need to look for something else to save them. It won't be 3G either.