I had to hold back with this blog entry a bit because I wanted to get permission first to write about what I would say was the most interesting demo I’ve been invited to during the 3GSM / Mobile World Congress:
Lots of WiMAX demos where shown at this years congress and it’s good to see that 802.16e mobile devices have now reached PC-card card sizes and are close to general availability. It’s also nice to see that when the antenna is just a couple of meters away you can see data rates beyond 10 MBit/s. However, that tells you only little about how the system performs in practice when the base station antenna is a couple of blocks away on top of a building and there is interference from neighboring base stations. To go the extra step, Intel and Motorola have teamed up to show how their kit works in a real environment during this years show.
In just a few days, Intel has put up four Motorola WiMAX base stations on rooftops in central Barcelona which were connected to the core network via 50 MBit/s microwave backhaul equipment from Dragonwave. Each base station was equipped with 3 sectors, each on its own 10 MHz channel in the 2.5 GHz band. In total they had three channels available for the network so each base station used the same set of frequencies. The distance between the base stations was about 2 kilometers which is a bit more then what you would see in an inner city network deployment. They couldn’t choose the sites themselves and had to be happy with what they got. On the upside, there is less interference from neighboring cells then there would be in a public network since there were only 4 cells and thus there is no interference from cells further away.
Sitting comfortably in the lobby of a hotel in Central Barcelona, I first had a chat with the technical project manager responsible for the network setup. Very good to have somebody with a technical background to talk to. During our discussion I got a first impression of the network performance as there were two notebooks connected to the network, one via a WiMAX PC-card adapter and the other via a CPE (Customer Premises Equipment) box the size of a DSL or cable modem. Despite sitting in the ground floor lobby, the base station being a couple of rooftops away on the other side of the hotel, the probably heat insulated and RF absorbing windows and just using the built in antennas of the devices we still got a data rate exceeding 2 MBit/s via both the CPE and the PC-card adapter. Note that both were SISO (Single Input Single Output) devices. As even this speed is far beyond what you can make use of while surfing the web we streamed a couple of video streams being sent live from WiMAX connected vehicles touring the city. The resolution of the stream was around 320×240 pixels and with a frame rate of 30 fps and the video streams were crisp and clear. One of the notebooks also had an engineering monitor software package on it to observe lower layer performance of the PC card and it was interesting to see how the card goes through the different modulation and coding schemes from QPSK to 64-QAM as reception conditions changed.
Later on we went outside and used Segways to speed up and down the streets with a notebook attached to it to see how the network copes with mobility. Again the video stream performance was flawless and we streamed a U.S. TV station over the Internet which is quite bandwidth hungry. But even this does not require a bandwidth beyond 5 MBit/s which was obviously not the limit of the network. When asked what the highest throughput is that can be observed in the network I was told that it is around 13 MBit/s with 64-QAM and about 1.5 MBit/s at the cell edge with QPSK ½ modulation and coding despite the fact that the cells are too far away from each other. Interesting numbers showing the direction in which we are headed once 2×2 MIMO is added and proper cell sizes are used.
Here’s a video taken and produced by Marc Wallis and Michael Ambjorn of Intel/Motorola respectively:
(copyright by M. Wallis / M. Ambjorn of Intel/Motorola)
I came away very impressed from the demo as the speeds were amazing. We didn’t loose the connection to the network even once during the one and a half hours sitting in the hotel and touring the city. That says a lot about the software stability of the PC-card and the network. Thanks a lot to Intel for the VIP tour invitation it was definitely the best demo I have seen during the Congress.
7 thoughts on “The 3GSM Gem in Barcelona: Intel and Motorola’s Live WiMAX network”
Interesting report. The data rates don’t seem that much better than those already available with HSPA. Did you come away with a feel for how the two technologies compare in the real world? Also, any idea how many users were connected simultaneously?
I think this is not a question of which technology is better but rather the type of mobile operator. UMTS incumbents are likely to go for LTE and possibly HSPA+ first since it fits nicely with their infrastructure they already have in place. Some CDMA operators like Verizon seem to be on the same bath. An exception to the rule seems to be Sprint with their preference for WiMAX in order to be first on the market with something beyond EvDO. Otherwise, in my humble opinion, WiMAX will be mostly used by new operators entering the market trying to break into wireless with new business models.
So the success of WiMAX will depend on how many emerging new operators can be attracted to the market and how well WiMAX fares in emerging economies.
in typical HSPA networks today you can see data rates of around 2.5 MBit/s. Even with new mobiles, it hardly ever exceeds 3 MBit/s. In this WiMAX network we could easily go beyond 6 or 7 MBit/s, something I haven’t seen in HSPA network yet. And it wasn’t even 2×2 MIMO yet. Concerning users per cell I would say only very few, it was a demo network after all.
And to be really fair, spectrum usage: typical HSPA 2x5MHz, WiMAX here 3x10MHz. Is that correct? Neither MIMO, yet. But TDD WiMAX has the edge for up/down flexibility me thinks. Is that important? Depends on how the market develops.
yes, in the demo network they were using a different carrier in each sector. With HSPA you use the same carrier in each sector and thus have more interference. You are correct, TDD up/down flexibility is better since you can adjust the time spent for uplink and downlink.
I’ve blogged about that before:
But TDD is more problematic when it comes to real network deployment as adjacent channel interference becomes more complicated due to mixed up/down usage. That’s when sync’ing becomes relevant and you lose some flexibility. Will this become a new ‘HDPA vs BluMAX’ battle or will handsets become totally flexible (with associated inefficiencies)? Competition is good but can lead to some compromise in performance.
Synching base stations is also good to increase performance with fractional frequency reuse:
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