WiMAX has been one of the industry buzzwords of recent years promoted by many members of the industry chain. The technology, which is specifically oriented to provide mobile broadband services, has now overcome many of the obstacles it initially faced to commercial application so is WiMAX finally ready for commercial use on a large-scale? by Wu Yilin, Huawei Technologies

Currently, there is a popular outcry in many parts of the world for "broadband everywhere." In the past, many 2G subscribers were not very satisfied with wireless Internet access service, largely because of big differences in bandwidth when compared with wired broadband access services. Through cooperation between IT (internet technology) and CT (communications technology), WiFi turned out to be a great success yet WiFi was still far from realizing the goal of "broadband everywhere" due to its limitations with regards to coverage, security, operations and so on. WiMAX came into being largely in response to this situation.

WiMAX is a wireless broadband standard developed by IEEE?Institute of Electricaland Electromics Engineers? and the WiMAX Forum. The WiMAX Forum serves as a promoter for the WiMAX industry and has more than 450 members consisting of operators, vendors and industry organizations. The WiMAX standard includes a number of variants. The IEEE 802.16d standard only supports its fixed application, and the IEEE 802.16e standard, covers both its fixed and mobile applications.
The WiMAX standard has been gradually maturing since 2001. From its air interface to its network architecture, WiMAX exhibits its superiority in almost very aspect. For instance, by using technologies such as OFDMA (Orthogonal Frequency Division Multiple Access), MIMO (Multiple-Input Multiple-Out-put ), AAS (Adaptive Antenna System) and AMC (Adaptive Modulation and Coding), the air interface takes the leading position in such aspects as capacity, coverage, and spectrum efficiency. What's more, the network has a flat All-IP architecture, which helps to reduce operators' CAPEX/OPEX, and also reflects the trend towards the emergence of the radio access network.
Massive investment in the technology in recent years has caused the price of the average WiMAX chip to drop drastically. This price reduction will certainly help to remove the largest obstacle to the commercial use of WiMAX – cost.

The second largest bottleneck in achieving the objective of "broadband everywhere" previously lay with subscribers' handsets. It has only been in recent years that the IT industry has seen the required technical progress and increased awareness in the requirements of personal communication devices. Only now have mobile Internet terminals seen the development from Ultra Mobile PC (UMPC) to Mobile Internet Device (MID), and become available more elegant, with better features, and at a reasonable price.

So WiMAX has gained wide-ranging support from many people in the industry. The end-to-end industry chain has been developing quickly in recent years, and problems relating to its standard maturity, equipment cost, and terminal bottlenecks have for the most part been solved. Nevertheless, as an emerging wireless access technology, WiMAX still has to face and overcome a number of other challenges before its successful commercial use. Here are some of the most critical barriers to widespread adoption.

Enhance the coverage
Experience in wireless network construction, operation, and maintenance shows that a network's total cost of ownership (TCO) is directly related to the number of BS sites it contains. In other words, a network with a small number of BS sites has a lower TCO than one with many and is therefore more likely to be deployed. For WiMAX to be deployed commercially then, by the same reasoning, the number of WiMAX BS sites has to be kept minimal while ensuring excellent coverage capability.

There are a number of ways this can be done.
BS coverage can be enhanced with multi-antenna technology such as MIMO (Multiple-Input Multiple-Out-put) BF or by increasing the transmitting power of the BS, or enhancing the BS's receiver sensibility. Additionally, successful 3G network construction cases clearly show that, through the use of the distributed BS solutions, where the RRU can be installed near the antenna, attenuation on the long feeder and the number of tower mounted amplifiers (TMA) can be reduced. All of these measures will result in wider coverage for BSs.

Cut O&M costs
From macro BSs, which cover thousands of square kilometers, to home FemtoCell BSs, which cover hundreds of square meters, mobile BSs have become elements with the most variable forms in a mobile network because of the diversity of application scenarios. Therefore, a complete WiMAX solution must accommodate a series of BS forms such as an indoor/outdoor macro BS, distributed BS, Pico BS, and Femtocell BS to satisfy various networking scenarios. Due to the diversity of BS forms and systems, mobile operators, especially those who also own GSM mobile networks, all encounter a great deal of pressure relating to network maintenance.

One way to reduce the cost of network operation and maintenance is to share All-IP BSs, that can be used for WiMAX, with other technologies such as GSM, CDMA and WCDMA so that fewer spare parts and fewer maintenance personnel are required. Plus, co-sited BSs with different technologies can share transmission equipment, power, antennae and feeders, and can be seamlessly integrated with IP networks.

Reduce backhaul costs
Reducing the costs for BS backhaul has been a hard nut to crack for wireless network operators but achieving a reduction in the bearer cost is an important factor for successful WiMAX network operation.

Because of the diversity of access network transmission technologies, WiMAX BSs must be adaptive to various transmission resources. One way to reduce costs is to provide various interfaces in the form of a pinch board which can avoid using external stand-alone transmission equipment, help reduce construction costs and intermediate NEs (Network Element), and also enhance network reliability and minimize network management workloads on transmission equipment.
A second way to reduce bearer costs is to use transmission resources more efficiently. Using the header compression is an effective means, especially for VoIP services, of saving up to 60% in terms of bandwidth. WiMAX requires a great deal of transmission bandwidth, so there is little point-to-point transmission between the BS and the GW (gateway) however, by means of service statistical multiplexing on the bearer network, more bandwidth can be saved in comparison with compression.
Finally, operators can lower BS bearer costs through self-backhaul. Compared with microwave, self-backhaul supports point-to-multipoint transmission, which permits uniform maintenance and installation together with the WiMAX product. The self-backhaul also solves the problem of non-line-of-sight transmission to some extent. With an upgrade in software, the self-backhaul fulfills the WiMAX mesh function, which leads to much lower operation costs.

Diversified requirements need to be ironed out
Operators tend to differ considerably in WiMAX network construction and operation modes. WiMAX's successful commercial deployment depends on whether the operator implements it in the most effective way. There are three main ways this is currently being done. New operators should choose the version most applicable to them.

GSM operators that do not have a 3G license, and CDMA operators usually strive to acquire low-cost data solutions, hoping to protect their existing investment, while trying to maintain continuity in subscribers' service experiences. They are likely to introduce WiMAX, at least in the beginning stages, while continuing to use their existing mobile network, so WiMAX can provide voice services and low-cost data services while resource sharing (such as sites and transmission equipment). This lowers WiMAX network construction costs and allows the network to be quickly deployed. Later, the services of the two networks can be integrated, facilitating the introduction of new services to attract subscribers. Furthermore, subscribers' experiences will be improved and mobile broadband services will be extended by means of sharing the NMS (network management system), billing system, bills, and SIM authentication.

Fixed network operators often suffer due to limited copper cable resources at the network end, which inevitably leads to difficulty in acquiring new subscribers. Hence these operators are often willing to use the radio access network to help them lower network costs, to solve the problem of the last mile in terms of broadband access, and to provide voice and broadband data access. However, they would require that the radio access network be seamlessly integrated into the existing fixed voice and broadband network. This being the case, a WiMAX+NGN VoIP solution would be their best choice, because it allows end-to-end voice services with high quality of service (QoS). WiMAX will also help them to facilitate network construction, or can be used to access the broadband radio access server (BRAS) to provide broadband access capability, and allow integration with the existing fixed broadband access and enterprise VPN services.

New mobile operators, on the other hand, are usually more eager to acquire a low-cost and technically advanced mobile network in one quick stroke, which would give them the ability to attract more subscribers, even at the expense of having incomplete network coverage. To construct a new network, an IMS+WiMAX mode can be directly used, which, by means of end-to-end dynamic QoS, is able to provide a more reliable platform to help operators develop VoIP, VT and Mobile IPTV services, and to make various new services available more quickly. Moreover, by means of interworking with 2G operators, operators are able to provide subscribers with dual-mode terminals, thus, compensating for network coverage left over from the earlier phase, and it will also give operators the ability to acquire more and more subscribers quickly.

Thanks to WiMAX, the dream of "broadband everywhere" is not too far from becoming reality, but there are still a number challenges that need to be overcome before WiMAX is likely to be used commercially worldwide. As we have seen, several barriers existed in the past which have now been overcome; I believe it is only a matter of time before the others identified above are also conquered. We have walked several hundred miles on the road to WiMAX's full commercial use. We only have one mile to go.

Although the move to MIMO offers benefits to network operators and users, its complexity sets test engineers a number of challenges, says Mark Elo

Today's radio devices use a SISO (single input single output) configuration with one transmitter and one receiver and information sent over a single channel.  MIMO (multiple input multiple output) transmission transmits information over multiple radio channels, but only occupies the bandwidth of a single channel. MIMO presents one of the most significant changes to happen to radio architectures in recent history. This technology can now be used in a wide range of commercial communications devices including mobile phones, PDAs, and laptops and is an integral part of the 802.11n and

WiMAX Wave 2 Standards.
Along with the benefits of increased bandwidth, multi-signal transmission and reception adds more layers of complexity. For instance, the transmitters must be aligned in time and phase and have a high degree of isolation from each other. This presents a number of unique testing challenges when moving from SISO to MIMO based systems that test engineers must consider.

From SISO to MIMO
The SISO configuration is used in almost all contemporary radio designs. Sometimes there may be an extra antenna for spatial diversity that is constantly switched for the best signal path. However, this is still considered to be a SISO system because there is a single up converter and a single down converter, a single demodulator/modulator, and a single data stream in the higher levels of the product's communications stack.

Multi-path effects can degrade a SISO transmission. For example, a Bluetooth signal with a symbol rate of 1M symbols per second must receive a symbol within a window of one microsecond. If multi-path effect delays the signal by more than this, a significant symbol error will occur. MIMO systems, on the other hand, require multiple paths. If two signals are transmitted with known characteristics, for instance a header, at the receiver end, one can assume what the signal should look like and create a model of the channel effects. When the unknown signal comes, i.e. the data, subtracting the channel effects can solve for the transmitted symbols. The key to a MIMO system, and why it is different from SISO, is that the behavior of the channel is critical and must always be understood.
There are three ways to transmit data using a MIMO configuration. The spatial multiplexing technique transmits different data on each channel, thus increasing the throughput. Spatial diversity transmits the same data on each channel. This redundancy in effect increases the robustness of the signal and improves the transmission coverage. Lastly is a method called beam forming. This technique improves the throughput and coverage by controlling the directionality and the shape of the transmitted signal.
A typical MIMO configuration can range from a 2×2 system, containing two transmitters and two receivers, to a 4×4 system with four transmitters and four receivers. Many commercial WLAN devices today employ a 3×2 configuration of three transmitters and two receivers. In the future, beam forming based systems could have up to 8×8 configurations.

Testing Challenges
Perhaps the greatest testing challenge for MIMO systems involves synchronisation with good channel isolation in the transmitter and the receiver. Transmission of multiple signals requires accurate synchronization of multiple channels in phase and sampling alignment. This means that RF test equipment such as signal analysers and generators must have precise alignment and excellent isolation between channels in order to make accurate and repeatable measurements.
For most test engineers, a major challenge is the ability to transition smoothly from single-channel to multi-channel testing and therefore choosing instruments that provide a clear and easy upgrade path to MIMO. For example, moving from WiMAX SISO to the MIMO versions based on Matrix A, B, and even C, the highest 4X4 configuration, can significantly lower test costs. Test engineers should also consider whether or not there is a clear upgrade path beyond the 4X4 Matrix C configuration.
Another major concern is keeping the cost of test per channel low while maintaining good performance, especially with respect to maintaining excellent channel isolation. This is important because measuring the channel characteristics is fundamental to verifying any MIMO device. The test equipment should ideally have independent transmitters and receivers for the best channel isolation and at least 14-bit or better amplitude resolution for good dynamic range.

Bandwidth is another important consideration. For Mobile WiMAX, the sub-carrier spacing is fixed at 10.94 kHz. The standard allows for FFT sizes from 128 to 2048, which means that the maximum signal bandwidth will be in excess of 20 MHz – so test equipment needs to have at least 20 MHz of bandwidth. If working with WLAN, then 40 MHz of bandwidth is even better for the 802.11n MIMO standard.

Instrument usability, or its user friendliness, is an often overlooked but equally important consideration. Intuitive displays are essential for debugging complex radio systems, especially when dealing with multiple signals. Going beyond the constellation diagram, users need to see how modulation quality behaves over time and over sub-carriers.

The measurements for SISO are similar to MIMO. For example, EVM is a key metric for establishing the quality of any digital signal. In a MIMO system, it is still important to understand the EVM performance of the system, i.e. the composite EVM. However, as part of the design process, it is also important to be able to understand the EVM performance of each channel, while it is in the presence of all the other channels. Here lies a significant challenge. For instance, if one of the transmitters is generating an in-band spurious signal, then the composite EVM would be degraded. The next step is to check the EVM of each channel or stream. In so doing, the engineer would notice that one of the streams has a degradation in EVM. This performance could be attributed to either time domain or frequency domain effects. By then observing the EVM of each OFDM carrier over the frequency, it will quickly become apparent that some in-channel distortion is causing the radios performance to be degraded.

Test engineers also need to see how the radio responds to changes in the channel, especially with different multi-path models. Channel response shows how all the radio transmissions interact with each other in the channel. In a 2×2 system the interaction is between TX1 and RX1, TX2 and RX2, TX1 and RX2 and TX2 and RX2. As the channel or stream count increases, the number of channel interactions also increases. For example in, a 4×4 system, the measurement needs to process 16 streams or channel responses to determine how each channel interacts with the other.

Beam forming also presents many test challenges. Beam forming is a technique that helps increase receiver sensitivity to the desired signal and decreases the sensitivity to interference and noise. This is accomplished by creating a series of beams and nulls in the transmitted signal. Test equipment for beam forming should be capable of finite phase and amplitude adjustment to be able to effectively create and receive specific patterns of radiation from each antenna.

Mark Elo is RF Marketing Director, Keithley Instruments

Handsets are already getting to market under-performing in certain areas – and tests for certain applications are still nascent. Adding LTE to the mix will only put more pressure on the test community, as they support developers working under ever more intense pressure

The increased capability of LTE devices presents a similar increase in the degree of complexity for manufacturers bringing these products to market. Simpler designs could once be tested at the manufacturing stage; however, the costs of addressing problems late in the development cycle are likely to prove unsupportable today, and the requirement has shifted to the R&D phases to catch problems earlier.

The progress of the standardisation work for 3G LTE is based on a set of high-level requirements, the principal aim of which is to further improve service provisioning and coverage, but at a reduced cost-per-bit compared to 3G for both operators and users. All this is to be achieved within the context of an enhanced user experience, operational flexibility that covers both existing and new frequency bands, improved data rates and reduced latency. As such, 3G LTE will provide the major leap forward, all of which brings with it significant testing challenges.

The compressed timeline for LTE standards development is reflected in the schedules for LTE product development. As specifications for the LTE radio interface stabilise, equipment manufacturers have begun to work on components for LTE base stations and user equipment. Operators have to upgrade their core networks to support LTE, and they undoubtedly want to have user devices available in quantity at the time of commercial launch. Suppliers of design and test equipment have to keep pace to provide the tools necessary for these tasks. Because of the newness and complexity of LTE technology, there are a range of engineering design and test challenges to address in the different parts of the LTE infrastructure:
RF: The variable channel bandwidths specified for LTE increase the system's flexibility and capability but also add to its complexity. The use of multiple antenna configurations and OFDMA to support high data rates adds further complication, although it's expected that by the time LTE products reach the RF testing stage, test engineers will be able to apply lessons learned from implementing MIMO and OFDMA in WiMAX. However, the use of SC-FDMA in the uplink will result in some challenges unique to LTE. With performance targets for LTE set exceptionally high, engineers have to make careful design trade-offs to cover each critical part of the transmit and receive chain.
Layer 1/Baseband:  To support the high data rates that are the goal of LTE, exceptionally large amounts of processing power are needed, particularly in the baseband, where all the error handling and signal processing occurs. Baseband designs will be modeled using PC simulation on both the UE and network sides, and reduced-speed emulation of hardware prototypes is also happening.
Layers 2/3: LTE Layer 2 is split into three sub-layers, including the Medium Access Control (MAC) and Packet Data Convergence Protocol (PDCP). Design challenges at this layer will be the handling of significant amounts of data in the PDCP and implementation of the 2ms MAC turnaround time. Layer 3 handles the main service connection protocols. Detailed specifications for both of these layers are still under discussion. Although early product development can be accomplished with simulation of these layers, the integrity of a device design cannot be determined until they are properly integrated with the baseband and RF sections at full operating speed.

Along with LTE-specific challenges are those associated generally with wireless design. Overall system performance depends on the performance of both the baseband and RF sections, and each is associated with particular impairments-for example, nonlinearities and noise figure in an RF up-converter or down-converter, phase and amplitude distortion from a power amplifier, channel impairments such as multi-path and fading, and impairments associated with the fixed bit-width of baseband hardware.

Not the least of all these challenges is the fact that LTE is an evolving technology, and as such is open to change and interpretation. The early availability of conformance tests will help alleviate interoperability issues and provide basic testing. However, from day one of commercial launch LTE must deliver an outstanding user experience in terms of voice quality, quality of data services, and battery life. For that reason comprehensive functional testing and real-world verification of LTE products is essential.

This in turn has put pressure on the test community as it is faced with not just testing protocols that are more complex, but also with dealing with technologies that are not stabilised in fixed standards. Nor are the challenges "merely" on the physical layer – pressure is being applied to produce tests in layer 2-3 that will ascertain the likely user experience of phones, rather than merely give a pass/ fail on.

At the moment, some European operators are reporting return rates on certain handsets of 50%, according top Spirent's Nigel Wright, Vice President of Wireless Product Marketing. But the surprising thing is, the reason for return has to with something as "simple" as handover.

"We talk to large operators in Europe, and 50% of some models are being returned – and these models are also the ones that are dropping calls the worst. And the biggest reason for dropping a call has been in handover failure," Wright says.

This is interesting because, as the industry looks forward to LTE, in all its OFDMA, MIMO, beam forming, 4×4 antenna complexity, the number one issue in returned handsets appears to be something this magazine was covering back in the early years of the decade – namely how to deal with handover between 3G and 2G networks.
Wright agrees.

"It is spectacular that this was not sorted out years ago. We were very surprised, but if you ask operators what their number one issue is right now they consistently say it's this. Most of them now keep a blacklist of handsets with performance issues."

As 3G LTE is an evolution of existing UMTS systems based on W-CDMA and will also fully integrate with existing GSM/GPRS/EDGE networks, seamless handovers will be critical to the gradual rollout of the first 3G LTE networks and deployment of the first LTE mobile devices. Such handovers might simply be inter-cell between neighboring 3G LTE cells or they could be handovers to W-CDMA or GSM/GPRS/EDGE as a user moves in or out of LTE coverage.

Wright thinks that much of the problem could be to do with a "GSM mentality", in which operators have always trusted and relied on conformance testing. In the CDMA world, where testing was less standardised, operators have long developed out their own test environments, in-house, to assure performance. So are European operators starting to take more responsibility for their own devices under management?

"They are starting to look at it." Wright says. "but I wouldn't say it's really been seen widely yet. There's still the GSM mentality of "if it's certified then it's good".

Yes even though handsets may have achieved certification, that is no guarantee of a consistent level of performance – and hence user experience – across handsets.

Here's Wright again. "It's really about achieving a minimum level of performance, of standardisation compliance. Yet in recent benchmarking for an industry analyst in the USA, we saw devices operating under identitical network conditions achieve two times the data rates of others, depending on the chipsets involved and the efficiency of the network and channel-related algorithms. That's a big difference.

"Significantly, we have started seeing large operators develop their own acceptance tests, versus accepting the terminals as they are. AT&T has put in a pretty significant back office and its own data performance testing."

But if HSPA has been showing up performance difficulties, LTE will place even more concerns on the operator and handset manufacturer side.

"Historically, new technology roll-outs have been subjected to delays, often due to problems experienced when the new technology mobile devices are tested against the new technology networks," says Aeroflex's Phil Windred.

For example, in order to obtain the all-important performance advantage for higher data rate mobile applications, the 3G LTE specifications will be based on a switch from W-CDMA to OFDM (Orthogonal Frequency Division Multiplexing) modulation technology. This represents a significant change at the very lowest level of the radio communications and achieving synchronisation will be a major challenge.

Complete visibility into the very lowest layers of the radio modem will allow users to diagnose the actual cause of a synchronisation problem rather than just knowing that synchronisation has failed.
Without the higher layer protocol, it is necessary to completely configure the physical layer using test scripts. As a consequence, many early test failures may not be the result of real problems, but rather by a mismatch in the setup between the prototype under test and the test equipment. With hundreds of parameters that need to be selected, the risk of a mismatch is significant.

A further implication of physical layer testing when the higher layer protocol is not available is that test automation is essential to ensure extensive and complete testing. The incorporation of test script configuration tools will allow the easy generation of all scripts needed to select the different configurations and tests. These various scripts can then be initiated by a test controller as required to synchronise control of the prototype under test and the test equipment. It will be possible to alter parameters in real time to enable test coverage to be extended across the wide range of different configurations used in a live system both in relation to test of the 3G LTE network and test of early 3G LTE prototype mobile devices. This will allow the early detection of software bugs associated with particular parameter values that will not otherwise be found until much later in the design cycle when diagnosing and rectifying errors tends to be much more expensive.

"With the current method of working for conformance testing, adding LTE capability means the scope of the tests required will end up being massive, and could still not cover all the performance envelope of the device," Wright says.

So how will the industry deal with the great scope of LTE device testing?
"I'm not sure how this is going to develop. Device manufacturers may be stuck with huge manadatory testing requirements, and operators cannot be sure even then if they will catch it all. It's going to be interesting to see how test approval evolves over the year. Something needs to change."

How will Mobile TV work when we hide out indoors or in the subway? Dr Peter Raabe, Radio Frequency Systems Global Product Manager – Wireless Indoor Solutions, explores the options

Just as consumers expect mobile phone and wireless data coverage everywhere indoors and underground, they will have the same expectation of broadcast mobile TV and WiMAX services–particularly since these will be received on the same multi-functional handsets. In fact, it is expected that the vast majority of mobile TV and wireless data interaction will take place ‘indoors', in venues such as homes and office buildings, plus busy public metros, shopping centres and airport terminals. Consequently, carriers are already exploring the level of coverage that will be required in these so-called confined spaces, and how to achieve it.

The practical approach will be to obtain as much coverage as possible from the outdoor network, which will be the starting point for deployment. But, although people's homes and some office buildings may be serviced in this way, a great many other key venues cannot be adequately penetrated by the outdoor network signal. This calls for the deployment of dedicated RF infrastructure to distribute the signal indoors.

Fundamentally, the principle of achieving wireless indoor solutions for broadcast mobile TV and WiMAX is no different from 2G, 3G and WiFi networks. Indeed, many key buildings around the region already have confined coverage infrastructure in place to support mobile phone, wireless data, and various radio services. These generally take the form of passive or active broadband distributed antenna systems (DAS) that support multiple services and carriers, and which now can be leveraged to provide coverage for broadcast mobile TV and WiMAX as well.

Adapt and adopt
One of the challenges will be adapting the existing systems to provide optimum coverage for these next-generation services. Take broadcast mobile TV in the first instance. Digital video broadcast to handhelds (DVB-H) mobile TV services are likely to be deployed in either the UHF or S-Bands. The UHF band (~470-720MHz) is close to the 800 and 900MHz cellular bands, so similar RF signal propagation and cable loss characteristics can be assumed. The S-Band (~2200MHz) is more likely to exhibit behaviour similar to the UMTS 2100MHz band.

WiMAX, on the other hand, operates at frequencies up to 6GHz–including the licensed and unlicensed 2.3-2.7GHz, 3.3-3.7GHz and 5.1-5.8GHz bands. At these higher frequencies, both signal propagation and cable loss characteristics are likely to be quite different, providing new challenges for coverage planners.

The other coverage planning issue that must be taken into account is that of how strong the signal needs to be for handset reception. This will vary significantly depending on whether the subscriber is stationary (such as sitting in an airport terminal), or moving (such as sitting on a subway train). In addition to signal level, both mobile TV and WiMAX reception at high speeds are highly dependent on the number of signal carriers and the type of signal modulation used.

The interaction of the indoor ‘microcell' with the outdoor network must also be considered in order to minimise interference. It is likely that mobile TV services in a given region will be allocated a single RF channel operating in single-frequency network (SFN) mode. Owing to licensing restrictions, this is anticipated to incorporate any indoor microcells as well as the outdoor network.
Conventional outdoor SFNs operate using complex signal timing and strict power levels to avoid co-channel interference. Although network planning is a challenge, the finely tuned network is essentially static once on-air. The introduction of indoor SFN microcells creates a dynamic environment that must therefore be carefully controlled, lest the balance of the total SFN is disrupted. Conventional indoor planning targets the indoor signal being stronger than what penetrates from outdoors, but when operating in SFN mode it is also important to exert strict control over the signal timing and power levels to ensure optimal coverage is achieved without interference.

Infrastructure evolution
Despite the broadband nature of much of the existing RF infrastructure, there is still much development work being done to allow systems to be upgraded in support of the new services. The heart of an indoor network is typically a broadband passive DAS, comprising broadband radiating cable or a distributed antenna network, which provides contoured RF coverage of a given confined area. These have evolved to be ideally ultra-broadband, allowing all services from 30MHz to 6GHz to share the same passive distribution system.

Wireless indoor solutions also incorporate many different active components that need to be fully functional in the new frequencies and bandwidths specified. These include repeaters and amplifiers to support RF-over-fibre systems, which are utilised in larger buildings and complexes where purely passive infrastructure is insufficient. In addition, methods of collecting the mobile TV or WiMAX signal for distribution indoors need to be considered. These typically include, besides BTS/transmitter combining systems in multi-band multi-service applications, either an off-air repeater and donor antenna assembly, or else a dedicated ‘customer premises equipment' (CPE) installation in the case of WiMAX.

As both WiMAX and mobile TV technologies gather momentum, the fact that consumer interaction will take place to a large extent indoors cannot be overlooked from both a network revenue and customer satisfaction point-of-view. This means the need for wireless indoor coverage has emerged as an essential factor to be considered in the overall business case. The successful realisation of such wireless indoor solutions will demand careful network planning and optimisation of both indoor and outdoor networks, supported by state-of-the-art wireless infrastructure.

Never mind TV – get into video

vTap from Veveo is a service that searches and indexes 115,000 web sites that carry large amounts of mobile video – totalling about 150 million video clips. It then encodes those videos on the fly to users who request them from their mobile device, using their vTap application. Its deployment could help operators unlock latent demand for access to user generated videos on the web, according to Guru Pai, VP of Marketing and Business Development, Veveo??"The free web video segment is a domain that's exploding," said Pai, "but it is disorganised and fragmented. We organize and find content, so we can deliver relevant video to our users regardless of whether they have carried out a specific vide search or are just browsing for content."??"Veveo has been active for a while in the internet but we now plan to do this in the mobile domain," Pai said. "There is increased complexity in terms of user input and display, but a user can find and view any content on the web in our index and then play it on their phone."??Users can either set up a profile on vTap, allowing the service to build up a list of recommendations and so on, or they can browse the index which is organized into about three million or so topics. All the main free internet sites plus news providers and TV sites are included in the index, Pai said.. The service carries out the on the fly transcoding and matching to which player the device has. ??Users can either take the service as a client on their phone, or as an xhtml solution. Pai said Veveo has an announced agreement with Motorola to include to client in its handsets, and has others agreed with other manufacturers that he can't reveal. The application would be somewhere inside a handset Video menu structure, he reckoned, or even on the browser page itself. ??Veveo's business case is to make money through advertising, with Pai currently saying it is in "audience building" mode. ?"Several ad networks think we've got something different," he said, "because either we have user profiles or targeted user queries. We can interleave ads with search requests or have ads on each xhtml page to interface with the rest of the mobile advertising industry."??As for the operators – they may need to change their business approach to video, Pai admitted, to benefit from such an app. If you look at operators like Verizon, it has about a thousand videos in a walled garden at any time, we have 150 million in our index" he said.?"I think operators are trying to figure out the video market. For linear TV they can address that through broadcast mobile TV, which has its place. But the non-linear user generated content world has hundred of millions of videos which is something mobile operators have not taken advantage of. Our value add is to work with operators to help get them addressing that audience. But today they are not doing a good job of monetizing that big audience for web video to the mobile device."??Pai said that vTap can interface with Facebook or other social networking site APIs to integrate people's profile into the mobile world.??"The science behind our services is very non trivial," Pai said. "It's not just an index and a simple search engine."??Currently Veveo says it has 500,000 users in either alpha, beta or some form of pre-launch usage. The company has attracted $28 million so far from VC, has 55 employees and was founded in late 2004.

Mobile Advertising – great white hope or flash in the pan? Avichai Levy and Yehuda Elmaliach look at the opportunities and challenges around mobile advertising, and explain how mobile operators can ensure their place as winners in a sustainable, successful mobile advertising market

Strategy Analytics predicts that mobile advertising will represent a fifth of global spending on Internet advertising by 2011 and will generate $14.4 billion of revenue, so it's easy to see why mobile advertising is being hailed as a major opportunity for the future. But who will be the beneficiaries of this upsurge of interest? Will it be the Internet giants like Google or Yahoo or will the content providers and brand owners reap the rewards, or perhaps this time the wireless operators will grasp the opportunity. I'd like to think that the mobile operators will heed the lessons earned by ISPs in failing to exploit the Internet advertising wave and make sure that they don't become just the dumb bit pipe vendor whilst the other players run off with the major spoils.

Snakes and ladders
At present the winners and losers are hard to predict. We are seeing a number of mobile operators dipping a toe in the water with pilot projects and Google has been quick to enter the fray by offering Ad words on the mobile phone as a default option to all its advertisers. The stakes are clearly high as 2007 saw the jostling for position by major companies in M&A activities such as Microsoft's acquisition of ScreenTonic, Nokia purchasing EnPocket and AOL snapping up ThirdScreenMedia, in a bid to buy in expertise in the mobile advertising arena. One thing is for sure, the traditional media owners in the print and broadcast world are right to be worried as industry experts predict that 2008 will be the year when advertisers start to earmark a significant portion of their advertising funds for mobile and online advertising.

A note of caution
Yet in this rush to capture the hearts and minds of the mobile user buoyed up by the encouraging signs in mobile content downloads, mobile operators are right to approach the matter with a degree of caution. A recent Forrester Research report discovered that although 79 percent of consumers find the idea of mobile ads annoying, consumers will happily engage provided that marketers deliver valuable information or content. So, whilst advertisers celebrate the mobile media for its ability to deliver interactive personal messages to the individual, the mobile operator needs to consider the user experience and respect their right to privacy. If the advert becomes intrusive or annoying or spoils the user's enjoyment of the music track they are listening to, or the video they are downloading, it could be counterproductive and actually cost operators' their customers.

Until now the main focus for mobile advertising has been on text ads and mobile web banners. Indeed the Mobile Marketing Association's only guidelines on mobile advertising exclusively focus on this approach. It's our belief that other rich media experiences such as Video (live and on demand), MMS, rich media WAP or In-Game offer greater promise for mobile ads and the opportunity to enrich the user experience and offer the advertiser a multi-channel approach which is likely to produce better results overall. Such an approach also lends itself most easily to the ad-funded content model.

Ad-funded Content
Any debate about mobile advertising would be incomplete without considering this model and I'd like to examine it from the operator, the advertiser and the user perspective. Firstly from the operator's perspective, who has the chance to supplement subscriber revenue with advertising revenue. As we know from other more traditional mediums the potential for advertising can offer substantial opportunities for a large and diversified income. Certain services lend themselves better than others to these kinds of promotions. Voice services for example are unlikely to be affected, but web 2.0 services can allow consumers to consume content for free based on an agreement to receive certain advertising messages. An example of such a service that could potentially be revolutionised by ad-funded content is mobile TV or "You Tube-like" services on the mobile. Users have expressed reluctance to pay to receive these services but the option of enjoying them for free at the advertisers expense is likely to prove more enticing.

But what about the advertiser? How compelling a medium will the mobile one prove to be? What will they need to convince them to spend their advertising budgets on this relatively untried new vehicle? Two of the key challenges for mobile operators will be to ensure the quality of experience is uniformly good for the user and that the brand itself is portrayed accurately and of a sufficiently high quality to satisfy the most discerning marketing VP. Unlike the Internet the mobile medium has a huge diversity of devices out there with different specifications and capabilities. The operator will need to be able to convince the brand owner that his brand will be communicated at a sufficiently high quality irrespective of the user's device.

Targeting and reporting
Another key requirement of the advertiser will be the need to ensure that the information is accurately targeted based on behavioural, geographic or demographic criteria and that they will obtain reliable measurable results. Since the mobile medium doesn't have the simplicity of the cookie to provide this service, the challenge of providing the brand owner with reliable usage statistics represents a significant challenge for many operators trialling mobile advertising services today. Mobile offers the potential for an interactive dialogue between the advertiser and the consumer and the ability for immediate results. Yet until the operators can provide the reassurance of real measurement metrics to advertisers the service won't take off.

Self-targeted viral advertising
From the users' perspective we've heard mixed reactions. But as yet there is little in the way of industry-wide regulation governing the do's and don't of mobile advertising. One area that we firmly believe to hold the potential for dramatic growth is the area of viral marketing in the mobile medium. Mobile communities such as MySpace and Bebo offer the potential for self-targeted advertising where users forward offers and content on to other members of their group. This offers the potential to extend the impact of a campaign beyond the operators own captive audience and identify people with similar interests, which could in turn be targeted by that operator with offers linked to that subject matter. What's more the recipient is far more likely to react positively to a message from their friend of colleague than from the operator or advertiser.

Enforcing user policies
So why you may ask hasn't mobile advertising already taken off in a big way? For the operators particularly there is a lot to win or loose. If they get it wrong they could risk alienating their customers, if they get it right it could offer a welcome new revenue stream. In the Internet environment the focus has been primarily on reaching the largest number of potential customers in an anonymous way. Mobile is different – it's much more personal. In the first place the operator has to reassure the user that if he opts out of receiving mobile advertising, that promise will be honoured. With no industry regulation determining how often an advert should arrive on a user's device, it is down to the operator to ensure the user isn't deluged with adverts and that policies governing the regularity of ads are strictly enforced.

To protect the user experience and ensure that only relevant ad content arrives on their screens, the ad solution they deploy has to be capable of leveraging the copious amounts of information the advertiser already holds on the customer by interfacing with their existing CRM solutions as well as other internal services such as Location Based Services, so that the advertising they receive is relevant to the recipient. The operator also needs to consider the ability to link to other off-portal content. Offering an advertiser the ability to combine access to off- portal content such as CNN mobile, with accurately targeted behavioural, contextual and demographic information would be an alluring prospect and enable the operator to charge up to ten times higher a price than an external ad seller or Off-Portal aggregator.

Protecting the user
So in summary, what are the key opportunities and risks associated with mobile advertising? For the mobile operator protecting the privacy and interest of their subscribers is paramount. They are legally bound to maintain their users' confidential data in-house and not sell it on to the highest bidder. There are, as we've seen, some interesting lessons to be learned from the Internet advertising experience. But the mobile medium holds some major differences and technical challenges to overcome in order to exploit the diversity of devices in the market. Another key prerequisite is the need to ensure a high quality experience for the user and fulfil the brand owner's specifications of how their logo or brand should be represented. There are numerous opportunities out there to be investigated using multi-channel, rich media such as video and MMS that are still largely being ignored and
the potential for leveraging self-targeting viral advertising over mobile communities is immense. We only hope that the mobile operators recognise the goldmine that they are sitting on and are ready to make sure that they and not the Internet search engine providers are the ones to reap the rewards.

Avichai Levy is VP Marketing and Yehuda Elmaliach CTO of Mobixell, a provider of mobile multimedia and advertising solutions (www.mobixell.com), and members of MMA (Mobile Marketing Association)