A quick recap of where we have been so far in the space of online services and web 2.0. In Chapter 3, we discussed the recommendation of webpages with an objective metric computed by Google from the graph of hyperlinked webpages. In Chapter 4, we discussed the recommendation of movies with subjective opinions estimated by Net ix from movie–user bipartite graphs.

Then we investigated the wisdom of crowds. In Chapter 5, we discussed aggregation of opinion in (more or less) independent ratings on Amazon. In Chapter 6, we discussed resolution of opinion conflicts in Wikipedia.

In this chapter, we will talk about dependence of opinions, taking a macroscopic, topology-agnostic approach, and focusing on the viral effect in YouTube and tipping in Groupon. Then in the next chapter, we will talk about the effect of network topology on the dependence of opinion.

As will be further illustrated in this and the next chapters, network effects can be positive or negative. They can also be studied as externalities (e.g., coupling in the objective function or the constraint functions, where each user's utility or constraint depends on other users' actions), or as information dependence (e.g., information cascades or product diffusion as we will see in this chapter).

A Short Answer

Viralization

YouTube is a “viral” phenomenon itself. In the space of user-generated video content, it has become the dominant market leader, exhibiting the “winner takes all” phenomenon. More recently it has also featured movies for purchase or rental, and commissioned professional content, to compete against Apple's iTunes and the studios.

To study a network, we have to study both its topology (the graph) and its functionalities (tasks carried out on top of the graph). This chapter on topology-dependent influence models does indeed pursue both, as do the next two chapters.

A Short Answer

Started in October 2003 and formally founded in February 2004, Facebook has become the largest social network website, with 900 million users worldwide as of spring 2012 at the time of its IPO. Many links have been formed among these nodes, although it is not straightforward to define how many mutual activities on each other's wall constitute a “link.”

Founded in July 2006, Twitter attracted more than 500 million users in six years. At the end of 2011, over 250 million tweets were handled by Twitter each day. Twitter combines several functionalities into one platform: microblogging (with no more than 140 characters), group texting, and social networking (with one-way following relationships, i.e., directional links).

Facebook and Twitter are two of the most influential communication modes, especially among young people. For example, in summer 2011's east-coast earthquake in the USA, tweets traveled faster than the earthquake itself from Virginia to New York. They have also become a major mechanism in social organization. In summer 2009, Twitter was a significant force in how the Iranians organized themselves against the totalitarian regime.

A crude answer is that interference management in WiFi does not scale well beyond several devices sharing one access point. When the crowd is big, the “tragedy of the commons” effect, due to mutual interference in the unlicensed band, is not efficiently mitigated by WiFi. To see why, we have to go into the details of WiFi's medium access control in the link layer of the layered protocol stack.

A Short Answer

How WiFi is different from cellular

Since their first major deployment in the late 1990s, WiFi hotspots have become an essential feature of our wireless lifestyle. There were already more than a billion WiFi devices around the world by 2010, and hundreds of millions are added each year. We use WiFi at home, in the office, and around public hotspots like those at airports, in coffee shops, or even around street corners.

We all know WiFi is often faster than 3G cellular, but you cannot move around too fast on WiFi service or be more than 100 m away from an Access Point (AP). We have seen many letters attached to 802.11, like 802.11a, b, g, and n, shown on the WiFi AP boxes you can buy from electronic stores, but maybe do not appreciate why we are cooking an alphabet soup. We have all used hotspot services at airports, restaurants, hotels, and perhaps our neighbor's WiFi (if it does not require a password), and yet have all been frustrated by the little lock symbol next to many WiFi network names that our smartphones can see but not use.

In this chapter, we examine the major software components of a mobile handset and the key design issues which affect their design. The Motorola DynaTAC, the world's first portable cellular handset, first announced in 1973, required minimal software, and utilized a simple microcomputer built with fewer than 2000 transistors. A modern smartphone, such as the iPhone 4GS, supports 16 Gbyte of flash and 256 Mbyte of RAM, and could have a billion transistors to perform all of the functions of the device. Given the range of software complexity over time, and the range of device types from a basic ultra-low-cost handset to a high-end tablet, we shall focus on core software elements which exist in various forms in all modern handsets, from ultra-low-cost handsets through to smartphones, and we shall define a model of software structure and its evolution which can be matched to these different device types. This approach permits us then to draw out the key design issues and how these have changed – or not – over time.

For explanatory purposes, we shall divide handset software into three broad groups, each of which has its own distinctive design issues:

• application software design – software related to the provision of applications and services to the user of the device, including underlying OS capabilities where applicable;

• protocol stack software design – software related to the exchange of messaging between the handset and the network in order to provide a set of mobile communication capabilities;

• physical layer software design – software related to the encoding and decoding of data via the air interface, and the control of associated hardware.

After examining each of these software areas and associated design issues, we shall conclude with a review of a set of broader design issues related to mobile operating systems, used in smartphones, and mobile execution environments, used in feature phones.

From the first mobile telephone call on a street in Manhattan, New York, in 1973, through to the six billionth mobile phone connection just short of 40 years later, the mobile handset has transformed our ability to communicate and connect. Its level of sophistication is astonishing, yet it has weaved its way so inextricably into the fabric of modern life that it is already challenging to think of how we ever survived without these devices. The next 40 years are sure to be just as exciting a journey, as the handset increasingly becomes our fundamental tool for interacting with people, information and things, both in the real world and the virtual world.

We have taken you on a journey from the early history to the foreseeable future of mobile handset design. Along the way, we have covered all of the key areas of handset architecture and technology design, and uncovered the most important drivers and influences on mobile handset design.

Advances in electronics following the invention of the transistor, at a pace described by Moore’s Law, have led to what we might call the “more laws” of: more processing power, more miniaturization, more complexity, more economies of scale, more market growth, more market diversity, more utility value, more apps – and ever more mobile handsets! However, counter-balancing these “more laws” are the unbending physical world constraints of limited spectrum availability, limits on the achievable information transfer through a communications medium and limits on the chemistry of batteries and the resultant battery capacity. In addition, there are practical limits on human cognitive load and manual dexterity which affect our ability to interact successfully with small physical devices that are becoming more and more complex.

Introduction

How the future will look in one, ten, or 100 years from now, no one really knows, as even how the mobile industry will change in three months’ time can't always be predicted. All we can do is share trends and insights into what we believe the environment will be like in the future, then assess how these trends are likely to shape and influence mobile handset design.

In this final chapter, several possible environments and landscapes that may exist in the future are explored, and the key technology drivers that may influence the handset design are identified. In order to match the possible environment, trends and landscapes with potential design changes, we are going to tell you a story. This story is of a woman going through her daily life in a few years’ time from now, using her handset to achieve everyday things. We will then discuss how the specific new technologies, applications, services or usage scenarios implied by the story fit into the typical handset design process, as described in Table 6.1 in Chapter 6. We repeat that sequence of events here, for convenience:

1. choice of materials,

2. user interface,

3. industrial design,

4. mechanical design,

5. hardware and software platform considerations,

6. channel to market,

7. design flow.

On October 31, 2011, statisticians at the United Nations believe that the world reached a global population of seven billion people. Industry analysts estimate that, a few weeks later, the six billionth active cellular phone connection was achieved. Even considering that some people have multiple phone connections, it is still incredible that the majority of human beings on our planet own a mobile handset – across all geographies, cultures and societies. The ability to connect to people and information, wherever you are and whenever you want to, is bringing into reality the concept of the global village and a shared humanity. Yet at least as amazing is the fact that this ubiquitous product is also the world's most advanced consumer electronics product ever. It is small, light, portable and affordable to most people. It can perform ever more functions, with increasing performance. How is this possible and how has this come to be? What really is involved in designing and bringing to market both the inner technology and the final desirable mobile handsets? How can new products be developed so quickly, and why are there so many to choose between?

This book is aimed at anyone who is curious about such questions, yet has limited time to invest. You can read the book completely over a weekend if you need a lot of knowledge quickly, or you can dip in and out of the book to gain insight into particular areas as you need them. Blaise Pascal in his Provincial Letters wrote “I would have written a shorter letter, but I did not have the time.” We have found the truth in this, as condensing down the key insights from as complex an industry as the mobile handset industry into the convenient format of the Wireless Essentials series has been a significant undertaking – it would have been easier to write a larger volume. However, the format offers you the benefit of being able to gain a really good appreciation of the technology, design processes and market issues involved in mobile handset design relatively quickly. As you read the book, we trust that you will gain good insight into a set of common design and market issues which re-appear consistently as we look at different aspects of both the underlying component technology and the handset product design process.

In this chapter we examine the most significant factors that good design teams consider when creating a new mobile handset design. The consideration of these factors and the design decisions taken have a major impact on the nature and success of the mobile handsets which are launched into the market. Designing a handset could be thought of conceptually as similar to cooking with a master chef putting together a new recipe. Different ingredients (design handset influences) are fused together to create the overall flavor of the dish (mobile handset) depending on the style of cuisine the customer is looking for (e.g. smartphone user or ultra-low-cost handset user). Underpinning the success of a good meal is usually the style and personality of the chef who is willing to take risks, innovate and try out new ingredients and methods of cooking, and at times to challenge traditional methods of cooking. This is no different to mobile handset design, where the culture, leadership and ability to challenge conventional thinking can contribute to new ways of creating and experiencing a mobile handset. We will explore the key design influences on mobile handset design, based on a framework of key contributing factors. We believe that careful consideration of these influences leads a design team to a position where they can successfully answer a very important question: “Why should users use this particular mobile handset versus any alternative?” The strength of the answer to this question is a measure of the “engagement value” of the resultant design.

Core design influence – engagement value

When commencing a new handset design, the first priority is to decide how to embed deeply into the handset the experience the designer would like the user to have throughout their use of the handset. The experience begins at the first sight of the handset through advertising and promotion, and continues through the purchase experience, first use, then daily use, including downloading of applications and access to services. Finally the experience should be extended to the process of disposing of the handset, and hopefully then buying the next new handset from the same manufacturer.

Introduction

In this chapter, we move the focus away from core handset components, designed to be used in many different handset designs, to the key principles involved in designing a particular handset. Drawing from the best design practice of handset designers who have created commercially and globally successful iconic handsets, two key themes emerge:

1. applying a holistic design approach;

2. embedding desirability at the start of the design process.

Holistic design is the integration and blending together of all of the individual design aspects – such as industrial, mechanical, user interface, hardware and software design – in such a way that a balance and synergy is achieved between the different design disciplines. The resulting handset should feel like a complete entity in and of itself, rather than a collection of things “stuck together.”

Desirability is the expression of the needs and desires of the mobile user, encapsulated within the design.

In order to achieve a successful handset design, it is critical to map out the user’s expectations, desires and needs at the beginning of the handset design. Elements of desirability must be injected into the overall handset design along each path of the design flow. This involves everything from choosing the colors and materials of the handset through to the way a user’s finger feels a feedback click on the touchscreen and even to the ambience felt when a customer enters a handset showroom. Mapping this out at the beginning of the design process is important in order to ensure a consistency and adherence to the user expectations and desires throughout the whole design process.

Having examined the factors which influence the essence of handset product design and what distinguishes one handset design from another, it is now appropriate to “lift the bonnet.” We need to gain a good appreciation of what the major component parts of a handset are, how they are put together, and what the major design considerations are. This exploration will expose us to a range of high-level technical design factors, which are unpacked in further detail in the hardware and software component chapters that follow. Our goal is to continue to develop understanding of the major design decisions and challenges faced by handset designers, which result from both rapid advances in technology and the equally rapid advances in market opportunities and expectations.

Design perspective

Immediately we are faced with dilemmas over how to describe the structure and organization of a mobile handset. Depending on where we sit in the design flow, what question we are trying to answer, and which information we are seeking to understand, we will view the internal structure and organization of a mobile handset design very differently. This is because a modern mobile handset is probably the world's most complicated consumer electronics product, and contains the combined efforts of many thousands of people over tens of years. It is possible for it to be so complex, at such a relatively low price, due to the very high volumes of sales achieved, allowing the costs of R&D and manufacture to be shared out (amortized) across millions of consumers who buy the products.

Introduction

In this chapter, we look at the major internal hardware components of a mobile handset and the key design issues which affect their design. We shall focus on core design aspects which are most particular to mobile handsets – radio, baseband cellular modem and mobile application processors. We shall look only briefly at the many – yet critical – peripheral components such as display, camera, audio, GPS, WiFi, sensors and so on. Our justification for taking this approach is that the core hardware and software components are the essence of what makes a mobile handset different to other consumer electronics products such as digital cameras, portable games consoles, SatNavs, set top boxes, etc. Many of these other modern consumer electronics devices also have displays, cameras, audio, memory, interfacing to other devices and connectivity options, so we shall focus on those aspects which most differentiate a mobile handset. In doing this, we are not, by any stretch of the imagination, under-estimating the importance which these other components play in creating a contemporary design. Indeed, these components are subject to the same core design constraints as the core handset components, and component manufacturers create peripheral products which are specifically suited to the design constraints of mobile devices.

Helicopter view

At a high level, Figure 4.1 illustrates the key functional hardware blocks which make up a modern handset such as a smartphone.

The mobile phone industry is one which has been characterized by a breathtaking speed of change and development, and anyone who has owned a number of handsets will be aware of the dramatic change evident between a phone of just a few years ago and the latest available models. In order to identify a set of core design issues which hold across generations of handset design, we need to set our sights higher than an analysis of the design of the latest high-end smartphone. We believe a very good place to start is with a review of the relatively short, yet thrilling, history of mobile handsets, providing an opportunity to understand the technological and market issues which have driven this phenomenal development.

Development of the first mobile handset

A famous telephone call

On April 3, 1973, Marty, a researcher at the US company Motorola, made a phone call from a Manhattan sidewalk to his colleague Joel Engel at the US telephone carrier AT&T.

The purpose of Marty’s call that particular Spring day was to inform Joel, that he, Marty, was calling him from the world’s first ever portable cellular telephone, beating AT&T in the technology race to develop a viable commercial portable cellular telephone. This first portable cellular phone was unlike anything we know today – consisting of about a kilogram of plastic and electronics, shaped something like a shoe, using analog radio technology, without any form of screen or menu buttons, and yet able to make and receive telephone calls “without wires” and when on the move. Marty, or, to give him his full name, Martin Cooper, is now revered by many as the father of the mobile phone.