Understanding the potential of network-based software location technologies

The Where Business
June 7th, 2010

IN-DEPTH: Interview with Manlio Allegra, president and CEO, Polaris Wireless. 

The ability to locate wireless handsets and devices in indoor environments is particularly important since that is where most users originate voice and data calls.

The importance of accurate, timely and efficient location indoors continues to grow rapidly.

The industry is also witnessing progress in this arena.

Santa Clara, California-based Polaris Wireless says the advantage of its solution is that it works well in non line-of-sight, cluttered environments - with indoors being a particularly challenging environment for cellular location systems.

According to the company, Polaris Wireless Location Signatures (WLS), capitalises on complex obstructions and shadowing to improve location performance.

The company says its hybrid solution performs better than A-GPS alone in both indoor and complex environments. Also, the company's solution is 4G LTE ready with the hybrid solution supporting multiple cellular air interfaces (2G/3G/4G) in a single platform in support of carrier's multi-mode services and devices.

In order to learn more, TheWhereBusiness' correspondent Ritesh Gupta spoke to Manlio Allegra, president & CEO of Polaris Wireless. Allegra is scheduled to speak at the forthcoming People Tracking & Location USA conference, to be held in Chicago on June 22nd - 23rd.

Ritesh Gupta: What new trends has the industry witnessed as far as the technology for indoor location is concerned? What sort of progress is being made in this arena?

Manlio Allegra: The first industry trend is really more of a collective realisation that A-GPS doesn't reliably work for indoor use cases. A-GPS is superb at turn-by-turn navigation and other outdoor uses, but GPS' utility stops at the front door so to speak. Indoor has to be addressed by other technologies more suited to that environment. Wi-Fi comes to mind first regarding indoor location, because Wi-Fi access points are inside many buildings. But there's a fatal flaw in that logic, since Wi-Fi access points inside buildings cannot easily be mapped  - even though Wi-Fi signals may be measurable inside the building, the locations of the sources are unknown and practically unknowable.

That leaves network-based software location technologies, such as Polaris' Wireless Location Signatures (WLS) as the best alternative to handle the indoor spaces. WLS uses measurements from cellular network signals, as well as Wi-Fi if available, and determines location by pattern matching against a geo-referenced database. Cellular signals radiate from base stations at known locations and their signals penetrate well inside buildings, or the buildings may have picocell base stations inside them.

These cellular signals are reliable sources for accurate location inside buildings to support applications such as social networks, friend/child finder, coupons/advertisements and asset tracking, which require indoor location capabilities.

RG: Can you provide an insight into advantages and limitations of Wi-Fi access points as far as indoor navigation applications are concerned?

MA: Wi-Fi access points are inside many buildings, but Wi-Fi is an unlicensed band technology operating on unplanned, unmanaged, dynamic and even mobile/portable networks. It's nearly impossible to reverse-engineer the locations of Wi-Fi radiators inside of most buildings - some special buildings, yes, but not for the general problem of location inside all buildings. Deep inside buildings, in a significant percentage of cases, handsets do not measure "known" Wi-Fi signals and hence cannot be located based on them - resulting in Wi-Fi location dead zones. Even if Wi-Fi sources could be mapped, they change all the time with new access points coming on line, others being shut down and many frequently moving locations. For example, in offices and hotels, IT departments enable and disable Wi-Fi servers on a daily basis to support special needs and meetings.

The dynamic nature of Wi-Fi networks is on the verge of exploding exponentially as Wi-Fi hotspot cards (e.g. Sprint's MiFi), smartphone hotspots and USB dongle hotspots proliferate. People now literally carry Wi-Fi hotspots in their pockets as they move around on foot or in vehicles, in addition to many buses and trains having Wi-Fi services. Determining the locations of these mobile and portable Wi-Fi radiators is literally impossible. Operating in an unlicensed band means that Wi-Fi runs in the same spectrum as microwave ovens (!), Bluetooth, cordless phones and other higher power users (amateur radio operators are licensed to transmit with 1,500 watts in the exact same frequency band as Wi-Fi). This renders Wi-Fi unreliable for mission critical or safety of life applications due to the unpredictable interference.

Turning on a nearby microwave oven can wipe out local Wi-Fi coverage. Finally, Wi-Fi capability exists in only a fraction of phones and it must be enabled by the user. Due to the increased battery drain or concerns about security, many users disable Wi-Fi in their phones, or only enable it in selective locations (e.g. home or office). In short, Wi-Fi doesn't solve the indoor problem.

RG: Can you elaborate on how Wi-Fi measurements in conjunction with the Polaris WLS location solution enhance accuracy, reliability and yield-particularly in dense urban and indoor environments?

MA: Due to the dynamic and ever-changing nature of Wi-Fi networks, Wi-Fi location on its own is highly unreliable, many times resulting in gross errors. Wi-Fi alone falls short; however, Wi-Fi signals used in combination with more reliable cellular signals make perfect sense. The cellular signal information allows the confidence and certainty of the Wi-Fi measurements to be determined. If confidence in the Wi-Fi measurements is good based on comparison with cellular information, then they can contribute to accurate location. This avoids the gross outlier errors that occur with Wi-Fi alone and makes optimal use of the Wi-Fi measurements. Pattern matching approaches like Polaris WLS blend cellular (2G, 3G and 4G) information with Wi-Fi to extract the best possible location estimate, providing far better accuracy, reliability and yield compared to Wi-Fi alone. Where Wi-Fi fails to get a fix, WLS can use cellular signals, yet when Wi-Fi information is good it can improve the performance of the overall system compared to cellular signals alone.

RG: As far as accuracy is concerned, it is being highlighted that the existing algorithms for determining location are close to the limits of what's possible, and any big leaps aren't expected in this area based on Wi-Fi alone. To what extent could hybrid Wi-Fi + inertial systems significantly improve accuracy because of the complementary aspects of the two systems?

MA: Wi-Fi alone doesn't solve the indoor problem because of its unlicensed band, unplanned, unmanaged nature. Inertial systems, or more broadly sensors in phones, such as compasses, barometric pressure altimeters, gyros and accelerometers, can be extremely useful for contextual information but are not very reliable for extended indoor navigation determination. For example, a compass can tell that a user's phone is facing in the direction of a particular statue or work of art in a museum to trigger playing the appropriate recording of a description. Sensors in phones can be used for limited navigation based on a last known good fix, but the location from the sensors quickly drifts after a short distance or time. Sensors need frequent and reliable good fixes between which they can dead reckon navigate. Wi-Fi alone doesn't provide reliable fixes deep inside buildings where access points can't be mapped. Therefore, sensors really need to be combined with other location technologies, such as Polaris WLS, which rely on cellular signals emanating from base stations at known locations. This provides the basis to take maximum advantage of the sensors for contextual information, such as which direction users are facing, whether they are stationary or in motion, whether they are going up stairs, etc.

RG: What sort of integrated hybrid location solution will be an enabler for 4G applications?

MA: 4G is all about "all IP" networks which deliver the low latency, high bandwidth experience that users have grown accustomed to on the wired Internet connections. 4G devices will be "always connected", so they are always on the network, enabling applications that run in the background to mine fresh content while the user is simultaneously accessing content in the foreground, such as web surfing. The 4G environment sets the stage for pervasive location that is transparent and seamless to the user. "Always on" location means that users in 4G will not turn on specific LBS applications to get a fix, but instead the network will always know where the user is - assuming he/she opts in. If the network and handset applications know where the user is at all times, they can perform location-relevant functions and deliver location-aware content. In 4G, as the user moves his/her wireless device will be able to anticipate what the user is doing. If you are heading home, the thermostat automatically gets adjusted and lights turn on. If you're shopping in the mall, then meaningful coupons can be delivered at the right time and place.

This location capability integral in 4G requires high accuracy, low latency, consistent and pervasive location functions. A-GPS/GPS can't do that alone. Pinging GPS for location fixes every few minutes would quickly drain the battery and wouldn't work indoors. Wi-Fi can't do that on its own, since it doesn't solve the indoor problem. That's what software-based approaches like Polaris WLS can bring to the table- the ability to frequently and accurately locate all users, both outdoors and indoors.

RG: How do you assess the emergence of software-only location platforms that can quickly determine the location of any Wi-Fi enabled mobile device? What's your viewpoint on advanced hybrid positioning algorithms to combine each of the location sources to arrive at a single position with a high degree of confidence?

MA: For future location systems, hybrid approaches combining handset-based A-GPS and network-based approaches will be the norm. That's the only way to deliver reliable service across all environments. The network-based approaches will not be Wi-Fi alone though. Wi-Fi has its advantages in certain scenarios, but it doesn't solve the indoor problem and is subject to gross errors. Instead, network-based approaches like WLS pattern matching, which blend cellular plus Wi-Fi measurements, do solve the indoor problem and eliminate large errors. Hybrid systems blending A-GPS plus WLS create the best of both worlds, delivering handset-based advantages for outdoor and open sky conditions, while leveraging network-based advantages for cluttered urban and indoor settings.

In all cases, the location approaches should be tailored to the Quality of Service (QoS) needs of the application. Various applications have vastly different location performance needs, not just in terms of accuracy, but also time to fix and battery drain. Safety of life applications, like E911, require the highest QoS accuracy and necessitate exercising all available location methods to arrive at a single best fix, but may not require the shortest time to fix. Mission critical applications, such as enterprise apps, warrant triggering the right methods to get a reliable fix, but not necessarily everything the handset is capable of doing. Interactive LBS applications may thrive on fast time to fix, so may not want to trigger technologies like A-GPS which could require ten seconds or more to get a fix. Persistent applications which must have frequent location fixes, say every thirty seconds, need to be light on battery consumption and hence trigger only particular location methods. Best effort applications, such as downloading a map of the neighbourhood or determining local weather, do not need high accuracy, so rudimentary methods may suffice. The main point is that advanced hybrid algorithms trigger the right mix of technologies based on the required QoS, then optimally blend them to give location performance that meets the application's needs. Always triggering all the available location technologies is not the best approach.

RG: LBS are useful only when users' locations are known; it takes a blend of several technologies to reliably achieve this, adding to device cost and complexity. How do you expect this sector to shape up?

MA: For LBS users, accurate location increases the value of the application and improves the user experience. To achieve LBS-required accuracy, multiple location technologies are required to consistently and predictably serve this segment. Handset costs do not necessarily need to increase to achieve the predictable and consistent accuracy. However, a hybrid combination of A-GPS and a network-based technology are required as each complements one another in specific areas of an operator's network.

For example, A-GPS works very well in outdoor/clear sky environments, but either degrades or fails when indoors and in urban environments due to urban canyons. Polaris's network-based solution, WLS, perfectly complements A-GPS in the areas that it fails - indoor and urban environments. Being a software-based solution, there are no changes or additional costs to the device. In addition, WLS works across all network technologies and all devices in the market.

RG: What's on your agenda for this year?

MA: There is a lot of activity in the US and increased demand for our solution. With the planned LTE deployments, carriers will be operating three distinct network technologies. AT&T, for example, will be operating 2G GSM, 3G UMTS and 4G LTE. Our solution serves this multi-network challenge elegantly within a single product and provides carriers flexibility with regard to altering their network without regard to how it might impact their E911 or LBS systems.

We are also seeing major infrastructure suppliers bring location platforms to the market for E911 and LBS. Our WLS solution is being integrated with these platforms to provide a best in class solution, bringing together WLS with A-GPS for Tier 1 operators around the world.

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