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Monday, August 13, 2012

The 4G Road Ahead: Some Common Denominators for WiMAX and LTE

For a long time, it has been held that WiMAX has a definite and powerful time-to-market advantage over LTE and LTE-Advanced networks. This is because of WiMAX’s maturity as a technology, but also due to its higher readiness to be deployed. On the other hand and despite the many commitments, LTE remains at the trial stage largely.

Recent market reports, however, indicate thatWiMAX’s advantage may be short-lived and that WiMAX, despite prospects of growth, will be eventually eclipsed by LTE’s growth, which is projected to take an exponential at the time of writing this article.

More generally speaking, both technologies share common facilitators and inhibitors when it comes to deployment. The following discusses some of these common aspects, including spectrum allocation, small cell concept, WiFi spread, the backhaul bottleneck, and operator readiness for 4G investments.

Spectrum Allocation...........................

Spectrum allocation and management, for example, have been observed to be an impediment when it comes to deploying LTE networks, particularly in Europe.This is especially the case given recent activating in auctioning spectrums in the 700 to 1000MHz range, in addition to the relevant auctioning policies and guidelines that have been set by the different regulators.

In the summer of 2011, the European Parliament meet to decide on the fate the 800 MHz, and whether it was possible to harmonize its allocation for broadband services. At that same time, UK’s Ofcom had decided to cap spectrum purchases in the then upcoming auction for LTE spectrum, and fears from monopoly in the then upcoming French auction had raised requests for a similar policy. A highly relevant debate that is currently taking place is one that is contemplating new models of spectrum allocations, management and trading.

At low frequencies, however, a lower number of base stations is required to cover the same the area. Areas that have been underserved until now, such as rural and suburbia, would therefore benefit greatly from such low frequency allocations. This tradeoff between frequency and deployment costs, however, should be viewed while minding capacity. To be noted however, high frequency and short range coverage can be especially effective in providing high capacity wireless links, especially when advanced antenna techniques, that is, MIMO, are exploited.

Small Cells.....................................

On the facilitation side, the “small cell” phenomena seem to be gaining great popularity on both the operators’ and the users’ side. Both 3GPP and IEEE have made extensive support for accommodating “small cells” that can be deployed either as femtocells, relay stations or out-of-band WiFi cells to which the IMTAdvanced users can be migrated to. Measures for inter-technology handovers, mandated by IMT-Advanced requirements, means that users can migrate their active connections to WiFi networks. Small cells benefit from the above noted advantages, achieving high capacity gains by both reduced coverage and limited subscriber access. In the case of WiFi networks, great cost savings are made as WiFi nodes operate in the unlicensed ISM band.

In addition to their other advantages, the economic advantages of relay stations have been repeatedly demonstrated in various techno-economic evaluations, and for both transparent and non-transparent relaying.

Such advantages have been demonstrated through different evaluation scenarios, for example, rural, suburban and urban, and under different antenna structures. It was found, for example, that relay stations can provide substantial gains in rural deployments made under high frequency spectrum allocations. Such deployments would naturally use non-transparent deployments as the interest would be largely in expanding coverage. Meanwhile, relay stations (mostly transparent) combined with the advanced antenna technique prove more useful in denser deployments commonly made in suburban and urban areas.
Offloading to femtocells and WiFi will reduce the traffic load on an operator’s backhaul network. In the various femtocell offerings that have been made in the market, operators may also gain increased revenues from fetmocells through monthly fees, greater loyal and reduced churn. Certain studies, however, have cautioned from generalizing cost reductions in all deployment scenarios. For example, it is possible to such gains in areas where there is a sparse macrocell deployment. The deployment of femtocells in these scenarios would overcome the indoor coverage challenge, and offer enhanced service rates – all at a much a reduced cost than increased macrocell deployments. Meanwhile, in areas where there is already a reasonable macrocell density, the benefit of femtocell deployment may be marginal.

The WiFi Spread.........................................

Meanwhile, WiFi deployments are continuing a steadfast wide deployments and at an international scale. It is now common to expect free or low-cost WiFi access in nearly all possible venues. The technology’s low deployment cost, in additional to minimal requirements of operational intervention, enable WiFi access providers to deploy very large networks in short durations. Vendors such as BelAir Networks, for example, continue to grow in their market share with their focus on small cells including both WiFi and femtocells, but largely the former. For example, BelAir offers Plug n’ play WiFi routers and femtocells with Power Line Communications that can be fit in very short times on existing power, diminishing infrastructure and rental costs for operators. 
WiFi deployments also continue to gain strong grounds in the enterprise.  Such large-scale deployments of WiFi networks open the possibilities of new business models. Through joint resource managements, operators deploying mixed access technologies will be able to manage the resources of the technologies in a joint manner, migrating users from one technology to the other based on operational objectives. At the same time, companies are now offering services that facilitate smooth inter-technology handovers, exploiting the recent advances and standardizations that have been made available.

The Backhaul Bottleneck..................................

One notable impediment to the realization of the full capacities of both  IMTAdvanced technologies (WiMAX and LTE) is the incapability of operator’s backhaul networks to cope with the advances at the radio interfaces.  Observations that have been made from the onset of the race towards the IMT-Advanced standardization still stand true today – that in terms of capabilities, both IMT-Advanced technologies stand on equal footing in terms of general performance and compliance to the overall ITU-R requirements. 

However, as is noted , many carriers are constrained by 1.5 Mbps (T1) backhaul, creating a definite limit on network performance, regardless of capabilities of the chosen radio interface. Existing technologies, including both packet microwave and fiber optics, are more than capable of answering the project user demands for IMT-Advanced. Investments decisions, however, have mostly been delayed by the debate on the technical qualities of both access technologies.

Readiness for 4G.........................

A note should be made here on the reluctance of incumbent cellular operators to invest in new infrastructures. Substantial investments were made by these operators in 3G networks, both backhaul and infrastructures, which partly justifies the delay as the full revenue potential of these networks is yet to be realized.

It is hence that many operators around the world have sought government support, especially through the most recent economic downturn. In many countries, including the US, Canada, Europe, Australia and New Zealand, economic surplus packages have dedicated funds to support expanded broadband infrastructures, especially when it came to rural and sub urban areas. Such funds, in addition to dedicated partnerships between governmental sectors at the different levels (i.e., federal, provincial, and municipal) and the private sector, are accelerating greater access to broadband Internet in many areas. At the same time, such initiatives are somewhat lessening the burden of expanding operator infrastructures. Another factor that impeded the realization of profits in deploying 3G networks stems from issues in patent management . It is hence that calls were made to “pool” the patents for LTE, and several initiatives – including the IIT initiative in Canada, where made with this objective. Patent pooling enables several companies to utilize each other’s patents when producing a certain product, substantially reducing the royalty fees.

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