4G - do we really need it?
Last week I was traveling a little bit. On most (if not for all) business trips my faithful ThinkPad
T41 laptop goes with me. I have entire office on this machine (after several upgrades I have 120MB hard drive and a new WiFi card). Having a schedule that was not too tight this time, I decided to measure real life performance of my Internet connections. Most of the time I was on a hotel or office wireless lan, but one particular day there was no WiFi available, so I had to use my Samsung SGH i600 as a modem. The results, based on speedtest.net are here on the right.
There is a clear pattern - most networks allowed me to download at around 1Mbps and upload with about a quarter of that speed (that is
256Kbps) with latency of 100ms. What surprised me a lot was the connection over my cell phone was not the slowest. In fact it was second fastest, scoring 1236Kbps download and 285Kbps upload with 150ms latency. And just to remind you, this is not a theoretical maximum speed, this was actually a real - life application - level performance. I have never had that high download speed over a cellphone before.
There is a technology called HSDPA or High Speed Downlink Packet Access, responsible by that level of speed. HSDPA has been adopted by many 3G mobile network operators. To achieve the
demonstrated level of performance HSDPA employs several technologies (adaptive modulation, fast packet scheduling and fast retransmissions), most of them implemented at the Node B's or UMTS base stations. HSDPA has an impressive roadmap as well, with speeds reaching 40Mbps and more. While being such an advanced technology, it has one extremely important feature. All the chipsets supporting HSDPA are backwards compatible with GSM standards. Therefore any HSDPA phone or modem will work over GPRS or EDGE, when the UMTS/HSDPA is not available.
Having said that I wonder what is the reason
companies like Sprint go for competing technology, namely the mobile WiMax. According to Sprint, the mobile WiMax network they are settinng up will allow for 3-4Mbps downloads and 512Kbps uploads. And they call it a 4G network. Where is the beef? To answer that question it is best to quote the recent HSPA GSMA document:
T41 laptop goes with me. I have entire office on this machine (after several upgrades I have 120MB hard drive and a new WiFi card). Having a schedule that was not too tight this time, I decided to measure real life performance of my Internet connections. Most of the time I was on a hotel or office wireless lan, but one particular day there was no WiFi available, so I had to use my Samsung SGH i600 as a modem. The results, based on speedtest.net are here on the right.There is a clear pattern - most networks allowed me to download at around 1Mbps and upload with about a quarter of that speed (that is
256Kbps) with latency of 100ms. What surprised me a lot was the connection over my cell phone was not the slowest. In fact it was second fastest, scoring 1236Kbps download and 285Kbps upload with 150ms latency. And just to remind you, this is not a theoretical maximum speed, this was actually a real - life application - level performance. I have never had that high download speed over a cellphone before.There is a technology called HSDPA or High Speed Downlink Packet Access, responsible by that level of speed. HSDPA has been adopted by many 3G mobile network operators. To achieve the
demonstrated level of performance HSDPA employs several technologies (adaptive modulation, fast packet scheduling and fast retransmissions), most of them implemented at the Node B's or UMTS base stations. HSDPA has an impressive roadmap as well, with speeds reaching 40Mbps and more. While being such an advanced technology, it has one extremely important feature. All the chipsets supporting HSDPA are backwards compatible with GSM standards. Therefore any HSDPA phone or modem will work over GPRS or EDGE, when the UMTS/HSDPA is not available.Having said that I wonder what is the reason
companies like Sprint go for competing technology, namely the mobile WiMax. According to Sprint, the mobile WiMax network they are settinng up will allow for 3-4Mbps downloads and 512Kbps uploads. And they call it a 4G network. Where is the beef? To answer that question it is best to quote the recent HSPA GSMA document:While confusion and hype abound concerning the real merits of WiMAX in the mobile environment, one key point receives less attention: true mobile broadband services are already here today.Nothing more to add. Unless 4G gives me 10-fold improvement (that would mean some 20Mbps or more), I am not willing to trade my HSDPA/3G-UMTS/EDGE/GPRS phone for some 4G WiMax device.
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