If we speak of humanity, it is on the basic assumption that it should be that which separates man from nature and is his mark of distinction. But in reality there is no such separation: ‘natural’ characteristics and those called specifically ‘human’ have grown together inextricably. Man, at the finest height of his powers, is all nature and carries nature's uncanny dual character in himself. His dreadful capabilities and those counting as inhuman are perhaps, indeed, the fertile soil from which alone all humanity, in feelings, deeds and works, can grow forth.

Thus the Greeks, the most humane people of ancient time, have a trait of cruelty, of tiger-like pleasure in destruction, in them: a trait which is even clearly visible in Alexander the Great, that grotesquely enlarged reflection of the Hellene, and which, in their whole history, and also their mythology, must strike fear into us when we approach them with the emasculated concept of modern humanity. When Alexander has the feet pierced of the brave defender of Gaza, Batis, and ties his live body to his chariot in order to drag him around to the scorn of his own soldiers: this is a nauseating caricature of Achilles, who abused the corpse of Hector at night by similarly dragging it around; but for us, even Achilles’ action has something offensive and horrific about it. Here we look into the bottomless pit of hatred. With the same sensation, we observe the bloody and insatiable mutual laceration of two Greek factions, for example in the Corcyrean revolution. When, in a battle between cities, the victor, according to the rights of war, puts the whole male population to the sword and sells all the women and children into slavery, we see, in the sanctioning of such a right, that the Greek regarded a full release of his hatred as a serious necessity; at such moments pent-up, swollen sensation found relief: the tiger charged out, wanton cruelty flickering in its terrible eyes. Why did the Greek sculptor repeatedly have to represent war and battles with endless repetition, human bodies stretched out, their veins taut with hatred or the arrogance of triumph, the wounded doubled up, the dying in agony?

Introduction

Wireless systems provide high flexibility and mobility support to their users. Each wireless system is allocated a fixed part of the available frequency spectrum for communication purposes. Table 3.1 lists the range of frequency allocated for some significant wireless services. A user in any wireless system is assigned a particular frequency within this pre-determined band either on permanent or on demand basis. With ever-increasing user density, planning the allocation of the available spectrum to users within the system has become important. Proper resource planning gives the following benefits: First, it aids in avoiding congestion and interference amongst the users. Second, efficient utilization of the otherwise limited frequency spectrum is obtained.

Vast varieties of multiplexing and access techniques are employed for efficient utilization of resources. Multiplexing is predominantly a physical layer function while access technique selection is a data link layer function of the OSI [Open Systems International] model. Multiplexing techniques help to divide the fixed system resource into multiple non-overlapping channels while access techniques are used to accommodate multiple users in these multiple channels, thus increasing the system user capacity Duplexing is another important process involved in preventing interference between uplink and downlink transmission from the same system entity. As multiplexing, duplexing and access methods are all interlinked in planning the resource allocation, they will be discussed together in this chapter.

Volume 1, Section 45

Twofold prehistory of good and evil. – The concept good and evil has a two-fold prehistory: firstly in the soul of the ruling tribes and castes. He who has the power to requite, good with good, evil with evil, and also actually practises requital – is, that is to say, grateful and revengeful – is called good; he who is powerless and cannot requite counts as bad. As a good man one belongs to the ‘good’, a community which has a sense of belonging together because all the individuals in it are combined with one another through the capacity for requital. As a bad man one belongs to the ‘bad’, to a swarm of subject, powerless people who have no sense of belonging together. The good are a caste, the bad a mass like grains of sand. Good and bad is for a long time the same thing as noble and base, master and slave. On the other hand, one does not regard the enemy as evil: he can requite. In Homer the Trojan and the Greek are both good. It is not he who does us harm but he who is contemptible who counts as bad. In the community of the good goodness is inherited; it is impossible that a bad man could grow up out of such good soil. If, however, one of the good should do something unworthy of the good, one looks for excuses; one ascribes the guilt to a god, for example, by saying he struck the good man with madness and rendered him blind. – Then in the soul of the subjected, the powerless. Here every other man, whether he be noble or base, counts as inimical, ruthless, cruel, cunning, ready to take advantage. Evil is the characterizing expression for man, indeed for every living being one supposes to exist, for a god, for example; human, divine mean the same thing as diabolical, evil. Signs of goodness, benevolence, sympathy are received fearfully as a trick, a prelude with a dreadful termination, a means of confusing and outwitting, in short as refined wickedness. When this disposition exists in the individual a community can hardly arise, at best the most rudimentary form of community: so that wherever this conception of good and evil reigns the downfall of such individuals, of their tribes and races, is near.

General Packet Radio Service

Introduction

GSM standard included voice and circuit switched data service. In circuit switched data service, the bandwidth is dedicatedly allocated to a user before data transfer. With increasing user base, the demand for new and higher data rate non-voice services grew. A new switching technique had to be designed. For the same GPRS [General Packet Radio Service] standard with packet switched data functionality was introduced in GSM networks. Table 9.1 lists the significant differences between circuit switched data service of GSM and GPRS.

The development of GPRS standard, which is often referred to as 2.5 G, was started by ETSI/SMG in 1994. As the packet switched principle was employed, this network had the capability to easily communicate with packet-based protocols like IP and X.25. Some new network entities were added in the already existing GSM network to allow the GPRS users to remain connected to the network and on the basis of requirement enjoy the data service. This led to a change in charging principle employed in the GPRS system. Several channel coding schemes were also used to increase per user data rate. Although theoretical data rate for GPRS user is high, in practice, it is averaged around 56 kbps. This standard of wireless communication is often referred to as the first step towards third generation.

Both the subscribers and the service provider have benefitted by the introduction of GPRS services. Some of the noteworthy advantages offered to the subscribers are as follows:

• • Subscribers can enjoy services at higher data rate. Theoretically, the maximum achievable speed is 115.2 kbps. However, in practice, the maximum data rate enjoyed by the end-user is 56 kbps.

Introduction

The cellular telephone system is one of the fastest advancing and popularly used wireless systems with an ever increasing user base. Subscribers can enjoy a wide range of services extending from high clarity voice service to high definition video service and finally high speed data service on the move. Owing to this immense benefit offered, wireless cellular systems are replacing their wired telephony counterparts. Today, the subscriber base of cellular telephone systems has crossed the billions user mark throughout the world. This chapter will begin with a brief outline of the development trend of cellular systems from the early analog communication system to the present UMTS and LTE systems. The rest of the chapter will throw light on the fundamentals of the cellular system design focusing on principles of channel reuse, clustering, handover, cause of interference and mitigation procedures.

Development Trend in Cellular Systems

The idea of a cell-based mobile radio system was first proposed at Bells Laboratory in the early 1970s but the commercial deployment of the system was done only in the 1980s after FCC allocated the proposed spectrum. Since then the wireless cellular telephone system has evolved to introduce new services and features. Table 7.1 lists some of the milestones that led to the development of the present cellular system.

The first generation systems were based on the analog communication system. Many standards were developed by different countries–AMPS in the United States, NMT in Scandinavia, NTT in Japan, RC2000 in France and TACS in Europe.

Introduction

In Chapter 1, the block diagram of a basic wireless communication system was explained.

In this chapter, the principle behind the working of a spread spectrum modulator and demodulator will be explained. Spreading as the name suggests is a technique by which a narrowband signal is transformed to a noise-like signal that has a wider bandwidth. Pseudo-Noise (PN) sequence is used for spreading or de-spreading the information signal. The transmission bandwidth allocated for any system is limited. Thus, using a spread signal for transmission of single user information can seem to be an inefficient technique. However, when a multi-user environment is considered, then the use of a spreading technique is beneficial in multiple ways. First, it permits multiple users information to spread and occupy the same bandwidth with least interference between each other. Second, on spreading, the signal becomes noise-like and can be de-spread only by the correct PN sequence. If de-spreading is attempted with any other PN sequence, the signal remains noise-like. Thus, use of the spreading technique ensures secured data transmission between the sender and the desired receiver. Third, it helps to prevent multi-path fading. Fourth, in multi-user systems, as all spread signals use the same bandwidth, there is no requirement of any frequency planning. Last but not the least, spreading a signal makes it immune to jamming.

Radio jamming is a collective term used for methods used to deliberately block or degrade the working of any wireless system including mobile telephony, satellite communication, CCTV systems and the like.

Introduction

Although it has come to be prized by many commentators as one of his most important texts, Nietzsche conceived On the Genealogy of Morality (1887) as a ‘small polemical pamphlet’ that might help him sell more copies of his earlier writings. It clearly merits, though, the level of attention it receives and can justifiably be regarded as one of the key texts of European intellectual modernity. For shock value no other modern text on the human condition rivals it. Nietzsche himself was well aware of the character of the book. There are moments in the text where he reveals his own sense of alarm at what he is discovering about human origins and development, especially the perverse nature of the human animal, the being he calls ‘the sick animal’ (GM III, 14): ‘There is so much in man that is horrifying! … The world has been a madhouse for too long!’ (GM II, 22). Indeed, in Ecce Homo Nietzsche discloses that an ‘art of surprise’ guides each of the three essays that make up the book and admits that they merit being taken as among the ‘uncanniest’ things ever scripted.

Nietzsche intended On the Genealogy of Morality as a ‘supplement’ and ‘clarification’ to his previous book, Beyond Good and Evil. That book, which has the sub-title ‘Prelude to a philosophy of the future’, is said by Nietzsche to be ‘in all essentials’ a critique of modernity that includes within its range of attack modern science, modern art and modern politics. Where the vision of the previous text, Thus Spoke Zarathustra was that of distant things, the vision of Beyond Good and Evil is focused sharply on the modern age, on ‘what is around us’. However, Nietzsche holds the two projects and tasks to be intimately related: ‘In every aspect of the book’, he writes in Ecce Homo, ‘above all in its form, one will discover the same wilful turning away from the instincts out of which a Zarathustra becomes possible’. In a letter to his former Basel colleague Jacob Burckhardt dated 22 September 1886, Nietzsche stresses that Beyond Good and Evil says the same things as Zarathustra ‘only in a way that is different – very different’.

Introduction

Wireless communication involves transmission of messages over radio channels which are prone to noise and interference. In order to ensure reliable transmission, several processes are involved both at the transmitting and receiving end. In Chapter 1, the block diagram of a wireless communication system was explained. This chapter will focus on coding, modulation, diversity and equalization techniques.

Source Coding

The end-user generates information that has to be transmitted towards the receiver. The generated user message may contain several redundancies that can be easily omitted such that the user message still remains in understandable format. Removal of redundancies to an acceptable limit is the main function of a source encoder. This main criterion behind the source coding principle leads to two types of coding techniques, namely lossless coding and lossy coding. The former type of source coding techniques ensures that the original user message is reconstructed at the receiver end. These coding variants are also referred to as entropy coding or noiseless coding techniques. On the other hand, in the latter type, the source coding is done in such a way that at the receiver end, only an approximation of the original user message can be reconstructed.

Depending upon the code length of the source encoder output and the corresponding user message length, lossless coding can be classified into four types:

• • Fixed-to-fixed mapping: In this technique, a fixed number of user message symbols are mapped to codeword of fixed length.

• • Fixed-to-variable mapping: In this technique, a fixed number of user message symbols are mapped to codeword of varying length. All the symbols in the user message do not have equal probability of occurrence.

Printed antennas are the most commonly used antennas in wireless applications where size is a constraint. The most basic form of printed antenna is the microstrip antenna that comprises a printed patch on the grounded substrate (Fig. A.1). In this text, a microstrip antenna will be designed. An antenna's performance is controlled by various parameters. The overall goal of any design is to obtain a stable output in the desired band. In order to achieve this goal, different factors on which the characteristic depends need to be examined and decided properly

The important considerations in the design of microstrip antenna are as follows

I. Substrate selection: Substrate in antenna design is principally needed for mechanical support of the antenna metallization. However, it also affects the performance of the antenna. There is no ideal substrate that will work equally well for all applications; in fact, the choice is completely determined by the application. The following points should be kept in mind before selecting any substrate.

• • Substrate thickness (h): A thicker substrate, besides being mechanically strong, will increase the radiated power, reduce conductor loss and improve impedance bandwidth. However, it will also increase the weight, dielectric loss, surface wave loss and extraneous radiation from probe feed.

• • Substrate dielectric constant (er): Low value of dielectric constant for substrate will increase the fringing field at the patch periphery and thus, the radiated power.

• • Loss tangent: A high loss tangent will increase dielectric loss and therefore reduces antenna efficiency.