Is M2M hype or the future of our information society? What does it take to turn the M2M vision into reality? In this article we discuss the business motivations and technology challenges for machine-to-machine communications. We highlight key M2M application requirements and major technology gaps. We analyze the future directions of air interface technology improvements and network architectures evolution to enable the mass deployment of M2M services. In particular, we consider the salient features of M2M traffic that may not be supported efficiently by present standards, and provide an overview of potential enhancements. Finally, we discuss standards development for M2M.

M2M: From mobile to embedded internet

In this paper we develop a framework for competition of future operators likely to operate in a mixed commons/property-rights regime under the regulation of a spectrum policy server (SPS). The operators dynamically compete for customers as well as portions of available spectrum. The operators are charged by the SPS for the amount of bandwidth they use in their services. Through demand responsive pricing, the operators try to come up with convincing service offers for the customers, while trying to maximize their profits. We first consider a single-user system as an illustrative example. We formulate the competition between the operators as a non-cooperative game and propose an SPS-based iterative bidding scheme that results in a Nash equilibrium of the game. Numerical results suggest that, competition increases the user's (customer's) acceptance probability of the offered service, while reducing the profits achieved by the operators. It is also observed that as the cost of unit bandwidth increases relative to the cost of unit infrastructure (fixed cost), the operator with superior technology (higher fixed cost) becomes more competitive. We then extend the framework to a multiuser setting where the operators are competing for a number of users at once. We propose an SPS-based bandwidth allocation scheme in which the SPS optimally allocates bandwidth portions for each user-operator session to maximize its overall expected revenue resulting from the operator payments. Comparison of the performance of this scheme to one in which the bandwidth is equally shared between the user-operator pairs reveals that such an SPS-based scheme improves the user acceptance probabilities and the bandwidth utilization in multiuser systems

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Demand responsive pricing and competitive spectrum allocation via a spectrum server

This chapter contains sections titled: Product Definition for Broadband Wireless Systems Technology Drivers Evolving Wireless Broadband Market Segments Open Systems and Intelligence at the Edge Radio Network System Engineering References

Always Best Connected

Mobile communication networks alone today consume 0.5 percent of the global energy supply. Meeting the rapidly increasing demand for more capacity in wireless broadband access will further increase the energy consumption. Operators are now facing both investing in denser and denser networks as well as increased energy cost. Traditional design paradigms, based on assumptions of spectrum shortage and high cost base station sites, have produced current cellular systems based on 3G and 4G (LTE) standards. The latter ones are characterized by very high spectrum efficiency, but low energy efficiency. Deployment has favored strategies with few high-power bases stations with complex antenna systems. The key method for indoor coverage has so far been to literally "blast signals through walls" - a solution that is neither energy-efficient nor very sound from a radiation perspective. As environmental aspects may be perceived as important from a societal perspective, the cost remains the short- to medium-term concern for operators of future mobile broadband systems. What becomes evident now is that the so far mostly neglected energy cost will be a major concern. Future system deployment has to balance infrastructure deployment, spectrum, and energy cost components. Ongoing incremental improvements in electronics and signal processing are bringing down the power consumption in the base station. However, these improvements are not enough to match the orders-of-magnitude increase in energy consumption cause by demands for more capacity. It is clear that solutions to this problem have to be found at the architectural level, not just by increasing the efficiency of individual components. In this article we propose a framework for a total cost analysis and survey some recent, more radical, "clean slate" approaches exploiting combinations of new spectrum opportunities, energy-efficient PHY layers, and novel deployment and backhauling strategies that target minimizing overall system cost. The latter involve network deployment tightly tailored to traffic requirements, using low-power micro base stations tailored specifically to decrease the power consumption compared to today's highpower macro base station schemes. To illustrate our findings, a power consumption model for mobile broadband access networks taking backhaul into account is presented, and the main trade-offs between infrastructure, energy, and spectrum costs are analyzed. We demonstrate optimal deployment strategies in some simple scenarios where a certain capacity has to be provided in a dense interference-limited scenario.

Energy- and cost-efficient ultra-high-capacity wireless access

The exponential increase in mobile data traffic is considered to be a critical driver towards the new era, or 5G, of mobile wireless networks. 5G will require a paradigm shift that includes very high carrier frequency spectra with massive bandwidths, extreme base station densities, and unprecedented numbers of antennas to support the enormous increase in the volume of traffic. This paper discusses several design choices, features, and technical challenges that illustrate potential research topics and challenges for the future generation of mobile networks. This article does not provide a final solution but highlights the most promising lines of research from the recent literature in common directions for the 5G project. The potential physical layer technologies that are considered for future wireless communications include spatial multiplexing using massive multi-user multiple-input multiple-output (MIMO) techniques with millimetre-waves (mm-waves) in small cell geometries. These technologies are discussed in detail along with the areas for future research.

Evolution towards fifth generation (5G) wireless networks: Current trends and challenges in the deployment of millimetre wave, massive MIMO, and small cells

A simple method for estimating the costs of building and operating a cellular mobile network is proposed. Using the empirical data from a third generation mobile system (WCDMA), it is shown that the cost is driven by different factors depending on the characteristics of the base stations deployed. When the site density increased, the operational and transmission costs tend to dominate rather than the radio equipment and site costs. The results also show how, for different capacity requirements, the costs can be minimized by a proper selection of macro, micro and pico base stations. In many scenarios, the macro base stations yield the lowest cost, indicating that the coverage (cell range) is an important parameter when designing wireless systems.

Relation between base station characteristics and cost structure in cellular systems

In this paper we analyze main use cases for sharing wireless access networks between multiple operators and service providers. Network sharing has been proposed as a method to lower roll-out costs for 3G operators in Europe, and is widely used in WLAN systems where local access providers offer wireless access to service providers. A similar structure also exists in cellular networks where mobile virtual network operators (MVNO) provide mobile services without having a mobile network of their own. The development points at a further fragmentation of wireless access networks into specialized service providers that connect to local service and access providers, possibly via an inter-connection provider serving with core network functionality. In this context, we propose a framework for how radio resources could be managed using service level agreements (SLA) and analyze key differences between the SLA for different types of service and network providers.

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Business models and resource management for shared wireless networks

Heterogeneous wireless access networks are today considered to be a key enabler for affordable wireless access to the internet. Thanks to the diverse usage patterns and quality of service requirements for mobile and wireless data services, operators may reduce their costs significantly by exploiting different radio access technologies. These are then accessed via 'multiradio' terminals that automatically select between available systems. As a means to identify efficient combinations of radio access technologies, we propose a methodology to estimate the total infrastructure cost for non-uniform traffic distributions. With a few numerical examples including the packet data optimised evolutions of third generation mobile systems (3G) as well as Wireless Local Area Network (WLAN) technology, the model is used to quantify the average total cost of different system configurations. The methodology should prove useful as a basis for more specific analysis of the economics of heterogeneous wireless access networks.

Modelling the cost of heterogeneous wireless access networks

As data applications become more popular in mobile networks, usage patterns will be different from mobile telephony. Demand for higher bit rates is found in certain areas ("hot spots"), whereas the requirement for wide area coverage remains. Previous work has shown that using classical cellular hot-spot techniques (e.g., micro-cells) with a single radio access technology imply high-cost solutions. Instead, combining several, carefully chosen, access technologies in an efficient manner, leads to reduced infrastructure related costs while retaining a sufficient quality of service. In this paper, we estimate the user data rates achievable by complementing an urban macro cellular high speed packet access (HSPA) system with different hot spot solutions. When deployed at comparable cost levels, "dense macro", micro, and pico HSPA base stations yield a similar performance in downlink. Thanks to more spectrum bandwidth, IEEE 802.11a WLAN supports higher data rates in downlink both on average and for the lower percentiles of users. For the uplink, which in principal is noise limited already with a few hot spots deployed, indoor (pico and WLAN) base stations outperform outdoor systems, which are subject to severe propagation losses for indoor users.

Cost Efficient Deployment of Heterogeneous Wireless Access Networks

In this paper we consider provisioning of high bit rate mobile services without the need of complex user terminals or deployment of a full coverage network with a very large number of traditional cellular base stations (access points) Existing broadband, Wireless Local Area Network (WLAN) and cellular solutions are combined with novel technologies such as ad-hoc network and Multiple-Input-Multiple-Output (MIMO) antenna systems in order to obtain high capacity links, highly flexible solutions and support for mobilityt. In the proposed solution we introduce an intermediate access point, or relay, that connects the end-user terminals to either a wireless or fixed network. Thus, a direct high bit rate connection between base stations and user terminals is not required, which would be beneficial both technically and cost wise. The proposed solution enables flexible rollout strategies and small-scale deployment for both traditional mobile operators and local access providers. The new type of equipment can also be owned and deployed by local actors like facility owners, hotels and private persons that imply possibilities for more flexible business models.

Klas Johansson

Papers

Relation between base station characteristics and cost structure in cellular systems

Business models and resource management for shared wireless networks

Modelling the cost of heterogeneous wireless access networks

Cost Efficient Deployment of Heterogeneous Wireless Access Networks

Relaying access points and related business models for low cost mobile systems.