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5G and IoT Supplement
Barry West, CTO and newly appointed president of Sprint Nextel’s 4G Business Group, has never shied from the challenge of paving new roads for emerging wireless technologies. As the former CTO of Nextel, West led the drive for push-to-talk communications over Nextel’s iDEN-based wireless network. And despite the air of skepticism that surrounds mobile WiMAX, West is confident that Sprint’s multi-billion dollar bet will pay off. West took time out at the recent WiMAX World conference in Boston to talk to Telecommunications® Editor Sean Buckley about the progress Sprint is making to deliver on its WiMAX 4G promise.
TM: Obviously, Sprint’s launch of its 4G intentions created quite a stir in the industry this past summer. Since formally launching your 4G intentions in August, how have things been progressing thus far?
West: Since announcing our intention of 4G, we’ve been in the process of putting the business unit together. The first step we have taken is that we have issued our RFP for a third tier-one vendor for the radio access network. We’ll probably bring in some smaller vendors for in-building solutions. We’re also out for a tender for different technologies to manage the backhaul. It sounds easy to say that was a lot of work. I think there were 6.5 thousand questions in these RFPs. Those are the main events that have occurred since we made our announcement. Obviously, we continue to test the equipment in our labs, and continue to meet with our vendors. My phone has been ringing off the hook with other people that would love to be that third [RAN] vendor. Also, a lot of companies that make consumer electronics equipment are talking to us about where mobile WiMAX is going, and how they can be part of that. I think our announcement has stirred the industry into a faster pace of action.
TM: You mentioned that enhancing in-building coverage would also be part of Sprint’s 4G plans. Could you talk to us about that and what it would entail?
West: In the world of cellular, getting the signal into buildings has always been a challenge. The usual way to do that is you crank up the power, but the problem with that is it creates interference on the street. In the case of mobile broadband, the attenuation going through the buildings has quite a significant impact on the speeds that are delivered. Rather than just blasting the signal from the outside, we are looking for solutions that radiate inside the building.
We can do that in a number of ways. If a building has access to the Internet, we can put a base station inside the building and connect it to the Internet connection, and bring it back into our network. The other way is to put an access point inside the building, which connects to the external network, but can transmit at higher power and has multiple antennas to improve the link budget.
TM: Here at the WiMAX show, there’s a lot of buzz around MIMO. What’s your philosophy around this technology, and is it ready for prime time?
West: Yes. The trick there is to get to multiple antennas in a device. I think the value in doing it is so significant, and the cost is negligible; I think that’s natural way going forward. In our trials with IP Wireless, we did a lot of work with them on multi-user detection, and those techniques will help reduce interference and increase throughput. Without those kinds of techniques, getting to 3 bits per-hertz will be impossible. I think with MIMO you can get into the 4-5 hertz range, but you’re adding to the complexity. It’s an economic balance between cost and complexity
TM: In the heady late 90s and early part of this decade, there was a lot of hype around pre-WiMAX technology at various trade shows such as WCA. Do you think the industry is now on a path of maturity?
West: We tend to forget the work the WCA did with the FCC to get the rules changed. That was a big piece. If you look back at the history of this [2.5 GHz] spectrum, it’s never been used to realize its whole potential for the country -- we’re going to change that. Without those rule changes, we would of never been able to do that.
TM: Sprint is part of the Next Generation Network Mobile Group. Can you tell us about that group and what it consists of?
West: NGNM is a group of operators that are trying to provide advice to vendors and the standards bodies about what the operators want on behalf of their customers. It’s not tied to technology. A lot of people think because the majority of operators in NGNM are 3G GSM operators, they think it’s about 3G LTE. It’s not. The principles of NGNM apply to all technologies. In choosing mobile WiMAX, we adhere to the spirit of the NGNM paper. The group was very careful to make the statement that Sprint’s adoption of mobile WiMAX does not put them outside of this forum. In fact, we bring something to the table in that they will get early insight into the kinds of services that are enabled by a true, mobile broadband, low-cost solution.
TM: Who’s heading up the NGNM group?
West: The original members of NGNM include Vodafone, Orange, T- Mobile, KPN, Sprint, DoCoMo, and China Mobile joined just before the initial round closed. Now, we just set up a company called NGNM UK LTD, which is a legal entity to make sure we don’t break any antitrust rules. As you can imagine the buying power of this group is very impressive. We’re out looking for someone to run that unit.
TM: When the WiMAX networks begin to roll out with live subscribers, there’s going to be an increased need for wireless backhaul. What options are you considering for network backhaul?
West: If you have a 20 MHz channel, and you can get 4 bits per-hertz; you got 80 Mbps per-sector, and 240 Mbps per site. If you’re going to try to push that down T-1s you’ll go broke. The challenge is, and the reason why we issued the RFP on backhaul, is to make sure we don’t have a choke point back in the network, either in terms of cost and throughput. We’re looking at everything, including in-band 802.16d solutions, proprietary solutions (because in backhaul it does not matter), and point-to-point microwave.
TM: So, for backhaul solutions it’s an all of the above scenario?
West: Yes. In each market, you’re going to use any combination because some sites you can get line of site, and in some you can’t. Mesh is a possibility. The only issue with mesh is that if you have too many mesh nodes, latency becomes a problem. There will be a compromise in terms of convenience in throughput with backhaul.
TM: Prior to making your WiMAX 4G intentions public, Sprint built a robust CDMA network. Do you see the WiMAX product as complementary to that existing network rollout?
West: Yes. It’s founded in the Internet Protocol, and it will be a flat network architecture. Basically, the IMS product will be able to work on our 1XEVDO or 4G networks seamlessly. Services will be delivered seamlessly across the two networks. It’s a complement to our 1XEVDO network. I think EVDO has a lot of life in it, particularly for voice services. The 4G wireless network is really data centric with lots of user- created video content, so the uplink-downlink have to be high performance.
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