Reflector Antennas
Reflector antennas are used as high-gain, narrow-beam antennas in fixed radio links, satellite communication, radars, and radio astronomy. A parabolic reflector antenna is the most common of reflector antennas. Figure 9.26 a shows a parabolic antenna fed from the primary focus. The equation of the surface is where F is the focal length. The rays coming from the focal point are converted parallel by the reflector or vice versa. A more physical interpretation is that the fields radiated by the...
Horn Antennas
An open waveguide end operates as a simple antenna. It has a broad, unsym-metrical beam and a rather large impedance mismatch. A much better antenna, a horn antenna, is obtained by widening the waveguide end, as shown in Figure 9.23. H-plane, E-plane, and pyramidal horns are fed from a rectangular waveguide. An H-plane horn is widened along the broad side of the waveguide, an E-plane horn along the narrow side. A pyramidal horn is broadened in both directions. The distribution of the aperture...
Example 82
There are many ways to translate data into binary equivalents. Example 8.1 showed one way to convert text into 4-PAM and then into binary. Another way exploits the Matlab function text2bin. m and its inverse bin2text. m, which use the 7-bit version of the ASCII code rather than the 8-bit version . This representation is more efficient, since each pair of text letters can be represented by 14 bits or seven 4-PAM symbols rather than 16 bits or eight 4-PAM symbols . On the other hand, the 7 bit...
Bending Refraction of Radio Waves in Troposphere
The refraction index n yje of the troposphere fluctuates over time and location. In normal conditions the refraction index decreases monotonically versus altitude, because the air density decreases. Because a phenomenon of this kind is a weak function of altitude, it causes slow bending of the ray. Fast changes in the refraction index cause scattering and reflections. Turbulence, where temperature or humidity differs strongly from those of the surroundings, gives rise to scattering. Reflections...
or for JLsa
0 1000 000 3000 4000 5000 8000 7000 8000 3000 1 0000 0 1000 000 3000 4000 5000 8000 7000 8000 3000 1 0000 0 1000 ZKJO 3000 4000 5000 6000 7000 8000 9000 10000 0 1000 ZKJO 3000 4000 5000 6000 7000 8000 9000 10000 0 1000 2000 3000 4000 5000 6000 70110 8000 9000 10W0 FIGURE 6.13 An automatic gain control adjusts the parameter a in the top panel automatically to achieve the desired output power. Perhaps the best way to formally describe how the algorithms work is to plot the performance functions....
Problems 1
6.15. Explore the behavior of steepest descent by running polyconverge .m with different a Try mu -.01, 0, .0001, .02, .03, .05, 1.0, 10.0. Can mu be too large or too small b Try N 5, 40, 100, 5000. Can N be too large or too small c Try a variety of values of x l . Can x l be too large or too small As an alternative to simulation, observe that the process 6.6 is itself a linear time invariant system, of the general form which is stable as long as a lt 1. For a constant input, the final value...
Diversity A Technique to Mitigate the Effects of Fading and Dispersion
18.4.2.1 Scope. We discuss diversity to reduce the effects of fading and to mitigate dispersion. Diversity was briefly covered in Section 9.2.5 where we dealt with LOS microwave. In that section we discussed frequency and space diversity. In principle, such techniques can be employed either at the base station and or at the mobile unit, although different problems have to be solved for each. The basic concept behind diversity is that two or more radio paths carrying the same information are...
Shortwave Radio
Frequencies between 3 MHz and 30 MHz are set aside for use in long distance radio communication. This frequency band is generally referred to as the short-wave band. The wavelength that lies between 1 m and 100 m is short compared to that of the medium wave. It was pointed out in Section 2.9 that the increased frequency of the carrier used in short-wave communication gives its electromagnetic transmission wave increasingly directional properties. Transmission antennae can be designed to...
Error handling
Diameter errors fall into two categories protocol errors and application errors. Protocol errors occur at the base protocol level and are treated on a per-hop basis e.g., errors in message routing may direct a downstream agent to take special action . Application errors are generated due to problems with specific Diameter applications. When a request message generates a protocol error an answer message is sent back with the E bit set in the Diameter header, indicating a protocol error. The...
Ccitt No 5 Signaling 85 Iscb
Switchblock TC4 TC4 Switchblock Figure 4.3-1 Supervision Signals of CCITT No. 5. a signal on send channel at ISC-A. b signal on receive channel at ISC-A. Signaling Frequencies. Two in-band signaling frequencies are used , 2400 Hz, and 2 is 2600 Hz. There are three signals ,, 2, and a composite signal that contains , and 2. Signaling Circuitry in Trunk Circuits. The functions and circuitry for supervision signaling in the TC4 circuits of analog CCITT No.5 trunks are similar to those discussed in...
Figure 915 Star and PeertoPeer Topologies
In a star topology data may be exchanged only between the network coordinator and the DEVs or network nodes no direct communication between DEVs . There are two types of communication uplink, from the DEVs to the network coordinator and downlink, from the network coordinator to the DEVs. In a peer-to-peer topology, each DEV can communicate with others within its radio range. There is no network coordinator. However, a DEV can become such a coordinator if it is the first device to communicate on...
OMA PoC Release 2
As the cellular networks evolve, they will be able to provide other more advanced IP-based real-time services than the plain voice services offered in the OMA PoC Release 1 specifications. Advanced services should, in this context, be seen as services that are more demanding in terms of bit rate and delay, and that offer improved possibilities of person-to-person communication and thus increase perceived user value compared to a plain voice call. OMA is trying to make use of the new...
Figure 1134 RRC Connection Establishment Procedure
Figure 11.35 illustrates the radio bearer establishment procedure. The radio bearer establishment procedure is initiated when the upper layers in the mobile station need to set up the transport and physical channels to accommodate the traffic flow from the upper layers. This procedure starts after the UTRAN performs the admission control and selects the parameters for the transport i.e., transport format set and physical i.e., channelization coding channels. 11.6.2.2 Radio Bearer Establishment...
Interleaving
The decoding result of the convolutional code strongly depends on the frequency and grouping of bit errors that occur during transmission. Especially burst errors during long and deep fading periods, i.e. a series of erroneous sequential bits, have negative impact on error correction. In such cases, the channel is not a binary channel without memory, rather the single-bit errors have statistical dependence, which diminishes the result of the error correction procedure of the convolutional code....
Contributors
David Kammer has been involved with the handheld industry since 1997. David is currently the Technical Lead for Bluetooth technologies at Palm Inc., and is one of the authors of the original Bluetooth specification. Before working on Bluetooth, David worked on IR technology, and on the Palm VII. In addition to his work at Palm, he also consults for several companies, including In2M and Microsoft, in the field of wireless communications and PalmOS programming. David has spoken at a number of...
Gigabit Ethernet
The IEEE 802.3z Gigabit Ethernet standard was completed in 1998 and established an Ethernet LAN that increased the transmission speed over that of Fast Ethernet by a factor of 10. The goal was to define new physical layers but to again retain the frame structure and procedures of the 10 Mbps IEEE 802.3 standard. The increase in speed by another factor of 10 put a focus on the limitations of the CSMA-CD MAC algorithm. For example, at a 1 Gbps speed, the transmission of a minimum size frame of 64...
Figure 813 Paging Sequences
In Standby, no connection has been established and the station can use all of its capacity to support Page Scan. If desired, the station can place ACL connections in the Hold mode or even use the Park mode before entering Page Scan. SCO connections are preferably not interrupted by Page Scan. In this case, Page Scan may be interrupted by the reserved SCO slots which have higher priority than Page Scan. At the connection state, a Bluetooth station becomes the member of a piconet. The station can...
Effective Length Average Height and Radius of Meteor Trails
Consider the ray geometry for a meteor burst propagation path as shown in Figure 13.7 between transmitter T and receiver R. P represents the tangent point and P' a point further along the trail such that R1 R'2 exceeds R1 R2 by half a wavelength. Thus PP' of length L lies within the principal Fresnel zone and the total length of the trail within this zone is 2L. Provided R1 and R2 are much greater than L, it follows that 5 angle between the trail axis and the plane of propagation A wavelength...
Asynchronous Vs Synchronous Vs Isochronous
Now we need to deal with the issue of synchronization, or timing. This requires synchronizing the transmitting and receiving devices. When I think of synchronization, I think of dancing, because if you and your partner are out of step, then disaster ensues. Fred Astaire and Ginger Rogers were dance partners that were always in step, or synchronized. Communications devices work the same way. There is bit, character byte , and message block frame packet synchronization that must occur before data...
Figure 57 MAC Frame Structure for Sectored Antennas
The MAC frame consists of Broadcast Channel BCH duration, Frame Control Channel FCH duration, Access Feedback Channel ACH duration and at least one Random Channel RCH duration. If there is transmission between the AP CC and the MTs, the Downlink DL phase and or Uplink UL phase are included in the MAC frame. If there is transmission among the MTs direct mode , the Direct Link DiL phase is also included. The BCH duration is fixed. The duration of the FCH, DL, DiL, and UL phases and the number of...
Tcp 302
timing recovery 300, 335, 645 Burst error model 157, 166-67, 176-77, 293 Bursty 21, 22, 29, 313-14, 318, 322, 340-41, 347, 380, 382, 396, 450, 466, 503-04, 628, 638-39 Busy hour 233 C language programs 72-79, 160 Cable modem 143, 344 Cable television CATV 2, 31, 33, 42, 110, 140-43, 195, 253, 258 CAIDA 86, 93 Care-of address 589-90 Carried load 824 Carrier sensing 26, 359, 361, 427, 450 Carrier sensing multiple access CSMA 359-61, 365, 425, 428, 454 Carrier sensing multiple access with...
Problems And Exercises Wsv
1 Above 10 GHz, there are two additional degradations to path loss that we must take into account. What are they 2 There are two frequency bands between 10 and 100 GHz that display high attenuation due to atmospheric gases. What bands are these Which one displays excessively high attenuation, making it unusable for most earth-bound applications. 3 Discuss two practical applications of the high-loss band in question 2. 4 Argue why cumulative annual rainfall rates may not be used for calculation...
The TISPAN Next Generation Network
Figure 3.23 The TISPAN NGN architecture. Figure 3.23 The TISPAN NGN architecture. ETSI TISPAN has developed an architecture to provide multimedia services over fixed accesses. This architecture is called Next Generation Network NGN and is based on the IMS. NGN is an access agnostic architecture able to provide IMS services to users using any type of access. This way, users can enjoy the same set of services regardless of the access they use. Therefore, TISPAN NGN achieves the much expected...
TCP Reliable Stream Service
The Transmission Control Protocol TCP provides a logical full-duplex two-way connection between two application layer processes across a datagram network. TCP provides these application processes with a connection-oriented, reliable, in-sequence, byte-stream service. TCP also provides flow control that allows receivers to control the rate at which the sender transmits information so that buffers do not overflow. TCP can also support multiple application processes in the same end system.6 Before...
Standing wave ratio
Standing waves have already been mentioned, together with their formation due to load termination. Figure 7.4 shows the result of producing standing waves on a transmission line. Remember that standing waves are produced when two waves having the same frequency and amplitude and travelling in opposite directions are superimposed. The figure shows that standing waves produce points of minimum and maximum disturbance called nodes and antinodes, and this applies to voltage or current waves....
Simulating The Ideal System
The simulation of the digital communication system in Figure 9.1 divides into two parts just as the figure does. The first part creates the analog transmitted signal, and the second part implements the discrete-time receiver. The message consists of the character string 01234 I wish I were an Oscar Meyer wiener 56789 In order to transmit this important message, it is first translated into the 4-PAM symbol set 1, 3 which is designated m i for i 1,2, , N using the subroutine letters2pam. This can...
magnitude spectrum shows the frequency content of the output signal
FIGURE 3.1 The element transforms the input signal x into the output signal y. The action of an element can be thought of in terms of its effect on the signals in time, or via the Fourier transform in terms of its effect on the spectra of the signals. Readers who have studied signal and systems often required in electrical engineering degrees , will recognize that the time domain representation of a signal and its frequency domain representation are related by the Fourier transform, which is...
The Home Subscriber Server and the Subscription Location Function
The Home Subscriber Server HSS is a database that stores the profile of all the users of a domain. A user's profile includes security-related information such as cryptographic keys, service-related information such as to which services the user is subscribed, and other information such as the S-CSCF that has been allocated to the user or the user's location. An HSS is supposed to be a central database for a domain. However, some networks have more users than a single HSS can handle. These...
Propagation Effects With A Low Elevation Angle
As the elevation angle of an earth terminal is lowered, the ray beam penetrates an ever increasing amount of atmosphere. Below about 10 , fading on the downlink signal must be considered. Fading or signal fluctuations apply only to the ground terminal downlink because its antenna is in close proximity to a turbulent medium. The companion uplink satellite path will suffer uplink fluctuation gain degradation only due to scattering of energy out of the path Ref. 16 . Because of the large distance...
CELP Speech Codecs
Most modern speech codecs are based on the Codebook Excited Linear Predictive CELP codec model 49 , where speech is synthesized according to a model of how the speech is produced by humans. The synthesis, in the decoder, follows the following steps 1. A fixed code book generates an innovation. This simulates the air flow created by the lungs. 2. The innovation is passed through a pitch predictor, which is also often called adaptive code book. This creates pitch pulses in a similar way as the...
WiMAX Simulator
Figure 13.13 illustrates the protocol structure of the WiMAX mesh MAC protocol stack. One of the functionalities of the mesh network entry protocol component is selection of sponsor node, which will involve communication exchange of unicast MSH-NENT from the new entry node and broadcast MSH-NCFG control messages from Figure 13.13 WiMAX mesh simulator protocol structure. Figure 13.13 WiMAX mesh simulator protocol structure. the sponsor node. In the design, the network entry process has been...
VIRTUAL LANs
Virtual LANs provide support for workgroups. A LAN consists of one or more LAN segments, and hosts on the same LAN segment can communicate directly through Layer 2 link layer without a router between them. These hosts share the same Layer 3 network layer subnet address, and communication between the hosts of one LAN segment remains in this segment. Thus Layer 3 network layer subnet address forms a broadcast scope that contains all hosts on the LAN segment. The workgroups are groups of hosts...
Eirp 1
MBC transmission loss Receiver antenna gain 73 dBm -180 dB 13 dB -94 dBm 107 dBm 13 dB occurring, of course, toward the end of a trail's useful life. Coding with appropriate interleaving is one method of mitigating these multipath effects. D-layer absorption often is neglected in link budget analyses of meteor burst links. We discuss D-layer absorption and its calculation in Chapter 12. Another source is CCIR Rep. 252-2 Ref. 10 . D-layer absorption, a daytime-only phenomenon, may exceed 3 dB at...
Architecture
The standard addresses two topologies ad hoc topology, referred to as Independent Basic Service Set IBSS , and infrastructure topology, referred to as Basic Service Set BSS . A topology that combines several BSS cells is referred to as Extended Service Set ESS . As shown in Figure 4.2, an ad hoc network or an IBSS consists of stations within mutual communication range of each other via the wireless medium. Such a network is created spontaneously, without preplanning, for ad hoc temporary...
Final and Intermediate GT Translations
In the above example, SCCP-E makes a final GT translation, which yields the PC SSN address of destination R800-D. This is possible because an SCCP in a signal transfer point has the necessary data to perform final translations for all destinations in its network, and we have assumed that all entities in Fig. 14.3-4 are in the same network. When the originating and destination ASEs are in different networks, the SCCPs in the originating network have no data to do final GT translations. In this...
Source Coding and Speech Processing
Source coding reduces redundancy in the speech signal and thus results in signal compression, which means that a significantly lower bit rate is achieved than needed by the original speech signal. The speech coder decoder is the central part of the GSM speech processing function, both at the transmitter Figure 6.2 as well as at the receiver Figure 6.3 . The functions of the GSM speech coder and decoder are usually combined in one building block called the codec COder DECoder . Figure 6.2...
Signaling Interfaces and Protocols
The interfaces and protocols for signaling between a MS and the PLMN are shown in Fig. 12.7-2 10 . ETSI has defined two interfaces the Um radio interface between a MS and the BSS, and the A cable interface between BSS and MSC. This is different from the U.S. cellular systems AMPS, IS-54 , where it is assumed that a MSC and its associated base stations BSs are supplied by the same manufacturer, and that the MSC-to-BSS interface is an internal manufacturer-specific interface. The A-interface...
Applications Of Perfluorinated Plastic Fiber
The raison d' tre for PFBVE GI-POF is to qualitatively simplify field installation of high-speed data links, especially in the gigabit-per-second regime. In comparison to silica-based optical fibers, GI-POF eliminates the need for trained installers and specialized cleaving and polishing tools. In comparison to high-speed unshielded twisted-pair UTP copper links, GI-POF simplifies the cable pulling and termination aspects of the installation process. As with all optical media, GI-POF also...
Common Channel Signalling
Introduction of SPC digital switching systems with high speed processors in the telecom network has necessiated modernisation of signalling. Also, in order to meet the transfer of varieties of informations for call management and network management and to satisfy the subscribers requirement on various features, the uninterrupted, high speed signalling has become inevitable. The rapid dvelopment of digital systems paved way for the new signalling system called common channel signalling. Instead...
TDMA System Clocking Timing and Synchronization It was
previously stressed that an efficient TDMA system must have no burst overlap, on the one hand, and as short a guard time as possible between bursts, on the other hand. We are looking at guard times in the nanosecond regime. The satellites under discussion here are geostationary. For a particular TDMA system, the range to a satellite can vary from 23,000 to 26,000 statute miles. We can express these range values in time equivalents by dividing by the velocity of propagation in free space or...
Numbering Plan For International Signaling Point Codes
The number plan described in ITU-T Rec. Q.708 Ref. 12 has no direct relationship with telephone, data, or ISDN numbering. A 14-bit binary code is used for identification of signaling points. An international signaling point code ISPC is assigned to each signaling point in the international signaling network. The breakdown of these 14 bits into fields is shown in Figure 14.8. The assignment of signaling network codes is administered by the ITU Telecommunication Standardization Sector previously...
Vswr 10
Ambient Temperature 24 C 75 F Atmospheric pressure, dry air Figure 15.9. Loss versus frequency for air dielectric coaxial cable. Courtesy of the Andrew Corporation Ref. 7. There are a number of important parameters to be considered for the application of coaxial cable as a transmission line. Probably the most important for the system engineer is attenuation or loss as shown in Figures 15.8 and 15.9. Loss varies with ambient temperature. The reference value in the figures is 24 C 75 F . Figure...
Correlation
Suppose there are two signals or sequences. Are they similar, or are they different If one is just shifted in time relative to the other, how can the time shift be determined The approach called correlation shifts one of the sequences in time, and calculates how well they match by multiplying point by point and summing at each shift. When the sum is small then they are not much alike when the sum is large, many terms are similar. Thus correlation is a simple form of pattern matching, which is...
Datagram Approach
In the datagram approach to packet switching, each packet is treated independently from all others. Even when one packet represents just a piece of a multipacket transmission, the network and network layer functions treats it as though it existed alone. Packets in this technology are referred Figure 9.2-2 shows how the datagram approach can be used to deliver four packets from station A to station X. In this example, all four packets or datagrams belong to the same message but may go by...
LOWER LAYERS 2231 ATM Layer
The ATM layer is responsible for cell formatting. An ATM cell consists of a 5-byte header and a 48-byte information field, for a total of 53 bytes. The size of the information field is the result of a compromise reached at the then CCITT between European and North American proposals. Both sides wanted a short cell for speed and efficiency, but Europeans advocated a 32-byte payload, while North Americans favored a 64-byte payload so it was agreed to split the difference. The header contains the...
ReverseBattery Signaling
Reverse-battery signaling employs basic methods 1 and 2 above, and it takes its name from the fact that battery and ground are reversed on the tip and ring to change the signal toward the calling end from on hook to off hook. Figure 4.12 shows a typical application of reverse-battery signaling in a common-control switch. In the idle or on-hook condition, all relays are unoperated and the switch SW contacts are open. Upon seizure of the outgoing trunk by the calling switch exchange trunk group...
PNNI Routing Protocol
Before addressing the signaling part of the PNNI protocol, a few words about the PNNI routing protocol are needed, since it plays a role that affects connection setup. Routing protocols are a basic function of packet networks and are used by Layer 3 nodes, such as routers, to exchange reachability and link status information without manual intervention. That exchange of information is done so that a route path from the source to the destination can be determined at all times, as nodes and links...
Scheduling MSHNENT in Control Subframe
In the mesh mode, transmission opportunities in the control subframe and minislots in the data subframe are separated. Each node competes the control channel access. The contention consequence in the control subframe does not have effect on the data transmission during the data subframe of the same frame. There are two different messages in the control subframes MSH-NENT and MSH-NCFG. Accordingly, there are two scheduling algorithms defined for these two messages. In this section, we will...
Routing and Wavelength Assignment for Primary Lightpath
For each new lightpath setup request, the LMN first solves the routing and wavelength assignment problem for the primary lightpath. The primary lightpath is selected from among the free wavelengths, and the wavelengths being used for backup. If there is a lightpath having the same source-destination pair as the new lightpath, the new lightpath is set up along the same route as the existing lightpath. This is because in IP over WDM networks, the IP layer recognizes that paths on different routes...
The Human Voice
Human voice communication depends on the voice-generating mechanism of mouth and throat being the initial transmitter, with the acuity of the ear being the receiver. Frequency components of the human voice extend down to some 20 Hz and as high as 32,000 Hz. The lower frequency components carry the voice energy and the higher frequency components carry emotion. Figure 5.1 shows a distribution of energy and emotion of the typical human voice. The human ear and many devices and components of the...