Monday, 29 September 2008

Bestseller Wireless Books at

Hi My Dear,

Let's see the Bestseller Wireless Books at

Wireless Home Networking For Dummies (Wireless Home Networking for Dummies)Wireless Home Networking For Dummies (Wireless Home Networking for Dummies) by Danny Briere
Buy new: $16.49 / Used from: $13.70
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802.11 Wireless Networks: The Definitive Guide, Second Edition (Definitive Guide)802.11 Wireless Networks: The Definitive Guide, Second Edition (Definitive Guide) by Matthew Gast
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Wireless Crash Course, Second EditionWireless Crash Course, Second Edition by Paul Bedell
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Wireless Communications & Networks (2nd Edition)Wireless Communications & Networks (2nd Edition) by William Stallings
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Wireless CommunicationsWireless Communications by Andreas
Buy new: $78.57 / Used from: $65.00
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Wireless Communications: Principles and Practice (2nd Edition) (Prentice Hall Communications Engineering and Emerging Technologies Series)Wireless Communications: Principles and Practice (2nd Edition) (Prentice Hall Communications Engineering and Emerging Technologies Series) by Theodore S. Rappaport
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LAN Switching and Wireless, CCNA Exploration Companion GuideLAN Switching and Wireless, CCNA Exploration Companion Guide by Wayne Lewis
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How Wireless Works (2nd Edition) (How It Works)How Wireless Works (2nd Edition) (How It Works) by Preston Gralla
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Hacking Exposed Wireless (Hacking Exposed)Hacking Exposed Wireless (Hacking Exposed) by Johnny Cache
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Wireless All-In-One Desk Reference For Dummies (For Dummies (Computer/Tech))Wireless All-In-One Desk Reference For Dummies (For Dummies (Computer/Tech)) by Todd W. Carter
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1 2 3 4 5 6 7 8 9 10 ... Next > >

Or you can click this link to see the Updated Bestseller Wireless Books .

Sunday, 28 September 2008

Huge new prime number discovered

Mathematicians in California could be in line for a $100,000 prize (£54,000) for finding a new prime number which has 13 million digits.

Prime numbers can be divided only by themselves and one.

The prize was set up by the Electronic Frontier Foundation to promote co-operative computing on the Internet.

The team from the University of California at Los Angeles (UCLA) found the new number by linking 75 computers and harnessing their unused power.

This enabled them to perform the enormous number of calculations needed to find and verify a new prime.

Now we're looking for the next one, despite the odds
by Edson Smith

Thousands of people around the world linked the powers of their personal computers in the search for a higher "Mersenne" prime number - named after 17th-Century French mathematician Marin Mersenne.

Mersenne primes are expressed as two to the power of P, minus one - with P being itself a prime number.

Edson Smith, the leader of the winning UCLA team, told the Associated Press news agency: "We're delighted. Now we're looking for the next one, despite the odds."


Friday, 26 September 2008

Semantic similarity

Semantic similarity

Semantic similarity, is a concept whereby a set of documents or terms within term lists are assigned a metric based on the likeness of their meaning / semantic content.

According to some opinions the concept of semantic similarity is different from semantic relatedness because semantic relatedness includes concepts as antonymy and meronymy, while similarity doesn't. However, much of the literature uses these terms interchangeably, along with terms like semantic distance. In essence, semantic similarity, semantic distance, and semantic relatedness all mean, "How much does term A have to do with term B?"

The answer to this question, as given by the many automatic measures of semantic similarity/relatedness, is usually a number, usually between -1 and 1, or between 0 and 1, where 1 signifies extremely high similarity/relatedness, and 0 signifies little-to-none.

An intuitive way of displaying terms according to their semantic similarity is by grouping together closer related terms and spacing more distantly related ones wider apart. This is common - if sometime subconscious - practice for mind maps and concept maps.

Concretely, this can be achieved for instance by defining a topological similarity, by using ontologies to define a distance between words (a naive metric for terms arranged as nodes in a directed acyclic graph like a hierarchy would be the minimal distance (in separating edges) between the two term nodes), or using statistical means such as a vector space model to correlate words and textual contexts from a suitable text corpus (co-occurrence).


1. Algorithmic Detection of Semantic Similarity
Automatic extraction of semantic information from text and links in Web pages is key to improving the quality of search
results. However, the assessment of automatic semantic measures is limited by the coverage of user studies, which
do not scale with the size, heterogeneity, and growth of the Web. Here we propose to leverage human-generated metadata — namely topical directories — to measure semantic relationships among massive numbers of pairs of Web pages or topics. The Open Directory Project classifies millions of URLs in a topical ontology, providing a rich source from which semantic relationships between Web pages can be derived. While semantic similarity measures based on taxonomies (trees) are well studied, the design of well-founded similarity measures for objects stored in the nodes of arbitrary ontologies (graphs) is an open problem. This paper defines an information-theoretic measure of semantic similarity that exploits both the hierarchical and non-hierarchical structure of an ontology. An experimental study shows
that this measure improves significantly on the traditional taxonomy-based approach. This novel measure allows us to
address the general question of how text and link analyses can be combined to derive measures of relevance that are in good agreement with semantic similarity. Surprisingly, the traditional use of text similarity turns out to be ineffective
for relevance ranking.

2.Roget’s Thesaurus and Semantic Similarity
A system that measures semantic similarity using a computerized 1987 Roget's Thesaurus, and evaluated it by
performing a few typical tests. We compare the results of these tests with those produced by WordNet-based similarity measures. One of the benchmarks is Miller and Charles’ list of 30 noun pairs to which human judges had assigned similarity measures. We correlate these measures with those computed by several NLP systems. The 30 pairs can be traced back to Rubenstein and Goodenough’s 65 pairs, which we have also studied. Our Roget’s-based system gets correlations of .878 for the smaller and .818 for the larger list of noun pairs; this is quite close to the .885 that Resnik obtained when he employed humans to replicate the Miller and Charles experiment. We further evaluate our measure by using Roget’s and WordNet to answer 80 TOEFL, 50 ESL and 300 Reader’s Digest questions: the correct synonym must be selected amongst a group of four words. Our system gets 78.75%, 82.00% and 74.33% of the questions respectively.

3.A new method to measure the semantic similarity of GO terms
Motivation: Although controlled biochemical or biological vocabularies, such as Gene Ontology (GO) (, address the need for consistent descriptions of genes in different data sources, there is still no effective method to determine the functional similarities of genes based on gene annotation information from heterogeneous data sources.
Results: To address this critical need, we proposed a novel method to encode a GO term's semantics (biological meanings) into a numeric value by aggregating the semantic contributions of their ancestor terms (including this specific term) in the GO graph and, in turn, designed an algorithm to measure the semantic similarity of GO terms. Based on the semantic similarities of GO terms used for gene annotation, we designed a new algorithm to measure the functional similarity of genes. The results of using our algorithm to measure the functional similarities of genes in pathways retrieved from the saccharomyces genome database (SGD), and the outcomes of clustering these genes based on the similarity values obtained by our algorithm are shown to be consistent with human perspectives. Furthermore, we developed a set of online tools for gene similarity measurement and knowledge discovery.

Roget’s Thesaurus and Semantic Similarity
A new method to measure the semantic similarity of GO terms

Saturday, 13 September 2008

CDMA technology

Multiple Access

The concept behind multiple access is to permit a number of users to share a common channel. The two traditional ways of multiple access are Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA).

In Frequency Division Multiple Access, the frequency band is divided in slots. Each user gets one frequency slot assigned that is used at will. It could be compared to AM or FM broadcasting radio where each station has a frequency assigned. FDMA demands good filtering.

In Time Division Multiple Access, the frequency band is not partitioned but users are allowed to use it only in predefined intervals of time, one at a time. Thus, TDMA demands synchronization among the users.


CDMA, for Code Division Multiple Access, is different than those traditional ways in that it does not allocate frequency or time in user slots but gives the right to use both to all users simultaneously. To do this, it uses a technique known as Spread Spectrum. In effect, each user is assigned a code which spreads its signal bandwidth in such a way that only the same code can recover it at the receiver end. This method has the property that the unwanted signals with different codes get spread even more by the process, making them like noise to the receiver.

Spread Spectrum
Spread Spectrum is a mean of transmission where the data occupies a larger bandwidth than necessary. Bandwidth spreading is accomplished before the transmission through the use of a code which is independent of the transmitted data. The same code is used to demodulate the data at the receiving end. The following figure illustrate the spreading done on the data signal x(t) by the spreading signal c(t) resulting in the message signal to be transmitted, m(t).
Spread Spectrum

Originally for military use to avoid jamming (interference created on purpose to make a communication channel unusable), spread spectrum modulation is now used in personal communication systems for its superior performance in an interference dominated environment.

Other Info:
Spread Spectrum Techniques by Dr.Jack Glas, an excellent introduction to spread spectrum

Processing Gain
In spread spectrum, the data is modulated by a spreading signal which uses more bandwidth than the data signal. Since multiplication in the time domain corresponds to convolution in the frequency domain, a narrow band signal multiplied by a wide band signal ends up being wide band. One way of doing this is to use a binary waveform as a spreading function, at a higher rate than the data signal.
Processing Gain

Here the three signals corresponds to x(t), c(t) and m(t) discussed above. The first two signals are multiplied together to give the third waveform.

Bits of the spreading signal are called chips. On the above figure, Tb represents the period of one data bit and Tc represents the period of one chip. The chip rate, 1/Tc, is often used to characterize a spread spectrum transmission system.

The Processing Gain or sometimes called the Spreading Factor is defined as the ratio of the information bit duration over the chip duration:

PG = SF = Tb / Tc

Hence, it represents the number of chips contained in one data bit. Higher Processing Gain (PG) means more spreading. High PG also means that more codes can be allocated on the same frequency channel (more on that later).

Other Info:

CDMA Technology
The world is demanding more from wireless communication technologies than ever before as more people around the world are subscribing to wireless. Add in exciting Third-Generation (3G) wireless data services and applications - such as wireless email, web, digital picture taking/sending, assisted-GPS position location applications, video and audio streaming and TV broadcasting - and wireless networks are doing much more than just a few years ago.

This is where CDMA technology fits in. CDMA consistently provides better capacity for voice and data communications than other commercial mobile technologies, allowing more subscribers to connect at any given time, and it is the common platform on which 3G technologies are built.

CDMA is a "spread spectrum" technology, allowing many users to occupy the same time and frequency allocations in a given band/space. As its name implies, CDMA (Code Division Multiple Access) assigns unique codes to each communication to differentiate it from others in the same spectrum. In a world of finite spectrum resources, CDMA enables many more people to share the airwaves at the same time than do alternative technologies.

The CDMA air interface is used in both 2G and 3G networks. 2G CDMA standards are branded cdmaOne and include IS-95A and IS-95B. CDMA is the foundation for 3G services: the two dominant IMT-2000 standards, CDMA2000 and WCDMA, are based on CDMA.

cdmaOne: The Family of IS-95 CDMA Technologies
cdmaOne describes a complete wireless system based on the TIA/EIA IS-95 CDMA standard, including IS-95A and IS-95B revisions. It represents the end-to-end wireless system and all the necessary specifications that govern its operation. cdmaOne provides a family of related services including cellular, PCS and fixed wireless (wireless local loop).

CDMA2000: Leading the 3G revolution
CDMA2000 represents a family of ITU-approved, IMT-2000 (3G) standards and includes CDMA2000 1X and CDMA2000 1xEV technologies. They deliver increased network capacity to meet growing demand for wireless services and high-speed data services. CDMA2000 1X was the world's first 3G technology commercially deployed (October 2000).

CDMA Deployments
CDMA is the fastest growing wireless technology and it will continue to grow at a faster pace than any other technology. It is the platform on which 2G and 3G advanced services are built.

Please visit the TIA website for more information on CDMA standards.

Other Info: CDG.ORG

Wednesday, 10 September 2008

4 Papers about Wireless RFID

Today search for the wireless-RFID paper from Google.There are several interested paper like these :-
(You can click the name to the source of links)
1. Wireless RFID Networks for Real-Time Customer Relationship Management.
A new system for real-time customer relationship management is based on deploying a network of RFID readers
throughout an environment. Information about the presence or lingering of participating
customers at different times of day is collected providing valuable
marketing information for better service provision. The implementation of the
proposed system includes a database management program and an intuitive
user interface allowing real-time access to the data acquired by the network.

In this paper the interested issue is Cost Comparison, about estimate the cost of deploying our wireless sensor network based
system and compare it with traditional systems. It had 2 tables comparison including
The major cost components in traditional systems and in the proposed technique and the costs are likely to be considerably less in the proposed system.

2.Cisco Case Study.
Full Name:-
Wireless Case Study: How Cisco Tracks RFID with Active RFID and Wireless LANs.

Active RFID tags and WLANs ensure compliance with corporate finance and government regulations.

This wireless case study describes an RFID project in Cisco India that evaluated how well the Cisco wireless LAN (WLAN) could detect equipment with active RFID tags, and how well it communicated data about equipment location to an internally developed asset tracking application.

This WLAN case study describes the best practices and benefits of the solution including:

* Identifying, in near-real time, the location of valuable equipment assets for consistent and centralized tracking
* Helping Cisco staff meet regulatory and audit requirements
* Applying Cisco IT’s existing investment in wireless networks

3. US Patent 7100835 - Methods and apparatus for wireless RFID cardholder signature and data entry

Inventor(s) * Selker, Edwin Joseph

About: A radio operated data card whose outer jacket forms a sealed protected housing for internal electrical components, including an RFID integrated circuit which incorporates data storage and a radio frequency transceiver, and one or more on-card antenna structures. Manually operated electrical switching elements, or antenna structures which are responsive to the positioning of conductive members, such as the human hand, at particular locations on or near the surface of the card, are connected to the on-card electronic circuitry. The switching elements or antenna elements are selectively operated by the cardholder who manipulates the card in predetermined ways to generate data signals that may be used to activate the card, store data in the card, or transmit data to the reader.

The Finally,RFID with Supply Chain Management...
4. Using RFID in Supply Chain Management for Customer Service
By:Hsiao-Tseng Lin; Wei-Shuo Lo; Chiao-Ling Chiang
Publish:Systems, Man and Cybernetics, 2006. SMC apos;06. IEEE International Conference on Volume 2, Issue , 8-11 Oct. 2006 Page(s):1377 - 1381
Digital Object Identifier 10.1109/ICSMC.2006.384908

Summary:Radio Frequency Identification (RFID) technology has been used since the Second World War, recent years it is widely employed in many areas such as highway tolls, in tracking livestock movements, in tracking air freight, medical care, air cargo operations, and in motor car manufacturing [1]-[3]. The year 2003 was crucial for RFID technology since both Wal-Mart and the Department of Defense of U.S.A. announced that they will be using RFID tags for pallets and cases in conducting business with their major suppliers. And even more, Wal-Mart suggested that it would extend the requirements to all of his suppliers by 2006 [4]. Thus, Wal-Mart could readily reduce their time of control and identification process for the suppliers and products. This may eventually lead to the accomplishment of their goal for Quick Response (QR) in their Supply Chain Management (SCM) and allow business to improve their customer relationship management (CRM) as well. In this paper, we discuss how the Radio Frequency Identification technology is used to solve the problems in supply chain management, the advantages of a business adopting RFID, and the relationship between RFID and CRM.

Saturday, 6 September 2008

ip routing protocol

What is IP Routing?
The purpose of the different IP Routing protocols and how they work.

Routing protocols implement algorithms that tell routers the best paths through internetworks. Routing protocols include Border Gateway Protocol (BGP), Interior Gateway Routing Protocol (IGRP), Routing Information Protocol, and Open Shortest Path First (OSPF) to name a few. Routing protocols provide the layer 3 network state update. Protocols that are transported through a network, such as Internet Protocol (IP), Novell Internetwork Packet eXchange (IPX), and AppleTalk are called routed protocols.

In short, routing protocols route datagrams through a network. Routing is a layer 3 function, thus, routing and routed protocols are network-layer entities. Routing tables on the layer 3 switch (router) are populated by information from routing protocols. A routed protocol will enter an interface on a router, be placed in a memory buffer, then it will be forwarded out to an interface based on information in the routing table.

Routing tables are critically important to the routing process. It is possible for these tables to be manually maintained by network administrators, but this is tedious, time-consuming and doesn't allow routers to deal with changes or problems in the internetwork. Instead, most modern routers are designed with functionality that lets them share route information with other routers, so they can keep their routing tables up to date automatically. This information exchange is accomplished through the use of routing protocols.

Note:-Some of the protocols in this section are generic enough that they could be applied to support the routing of any network layer protocol. They are most often associated with IP, however, as TCP/IP is by far the most popular internetworking protocol suite, and that is my assumption in describing them. Also, this section focuses primarily on the routing protocols used in Internet Protocol version 4. There is limited discussion of IPv6 versions of the protocols at this time.

-TCP/IP Guide

Tuesday, 2 September 2008

IP Routing

What is IP Routing?
IP Routing is an umbrella term for the set of protocols that determine the path that data follows in order to travel across multiple networks from its source to its destination. Data is routed from its source to its destination through a series of routers, and across multiple networks. The IP Routing protocols enable routers to build up a forwarding table that correlates final destinations with next hop addresses.

These protocols include:
BGP->Border Gateway Protocol
(More details:Data Connection, Cisco)
IS-IS->Intermediate System - Intermediate System
(More details:Data Connection, Cisco)
OSPF->Open Shortest Path First
(More details:Data Connection, Cisco)
RIP->Routing Information Protocol
(More details:Data Connection, Cisco)
OER->Cisco Optimized Edge Routing
(More details:Cisco)
EIGRP->Enhanced Interior Gateway Routing Protocol
(More details:Cisco)
IGRP->Interior Gateway Routing Protocol
(More details:Cisco)
OSPF->Open Shortest Path First
(More details:Cisco)
ODR->On-Demand Routing
(More details:Cisco)
MBGP->Multiprotocol BGP
(More details:Cisco)

When an IP packet is to be forwarded, a router uses its forwarding table to determine the next hop for the packet's destination (based on the destination IP address in the IP packet header), and forwards the packet appropriately. The next router then repeats this process using its own forwarding table, and so on until the packet reaches its destination. At each stage, the IP address in the packet header is sufficient information to determine the next hop; no additional protocol headers are required.

The Internet, for the purpose of routing, is divided into Autonomous Systems (ASs). An AS is a group of routers that are under the control of a single administration and exchange routing information using a common routing protocol. For example, a corporate intranet or an ISP network can usually be regarded as an individual AS. The Internet can be visualized as a partial mesh of ASs. An AS can be classified as one of the following three types.

* A Stub AS has a single connection to one other AS. Any data sent to, or received from, a destination outside the AS must travel over that connection. A small campus network is an example of a stub AS.

* A Transit AS has multiple connections to one or more ASs, which permits data that is not destined for a node within that AS to travel through it. An ISP network is an example of a transit AS.

* A Multihomed AS also has multiple connections to one or more ASs, but it does not permit data received over one of these connections to be forwarded out of the AS again. In other words, it does not provide a transit service to other ASs. A Multihomed AS is similar to a Stub AS, except that the ingress and egress points for data traveling to or from the AS can be chosen from one of a number of connections, depending on which connection offers the shortest route to the eventual destination. A large enterprise network would normally be a multihomed AS.

An Interior Gateway Protocol (IGP) calculates routes within a single AS. The IGP enables nodes on different networks within an AS to send data to one another. The IGP also enables data to be forwarded across an AS from ingress to egress, when the AS is providing transit services.

Routes are distributed between ASs by an Exterior Gateway Protocol (EGP). The EGP enables routers within an AS to choose the best point of egress from the AS for the data they are trying to route.

The EGP and the IGPs running within each AS cooperate to route data across the Internet. The EGP determines the ASs that data must cross in order to reach its destination, and the IGP determines the path within each AS that data must follow to get from the point of ingress (or the point of origin) to the point of egress (or the final destination).

The diagram below illustrates the different types of AS in a network. OSPF, IS-IS and RIP are IGPs used within the individual ASs; BGP is the EGP used between ASs.

IP Routing Image

Data Connection

Monday, 1 September 2008

Ad-hoc network and Pro-active Routing Protocal Part2 : Destination-Sequenced Distance-Vector Routing (DSDV)

Ad-hoc network and Pro-active Routing Protocal Part1: AWDS and Babel.

Type of protocols
Pro-active Routing (Table-driven)
This protocols maintains fresh lists of destinations and their routes by periodically distributing routing tables throughout the network. The main disadvantages of such algorithms are -

1. Respective amount of data for maintenance.
2. Slow reaction on restructuring and failures.

Examples of proactive algorithms are (con.)-
C).Destination-Sequenced Distance-Vector Routing (DSDV) is a table-driven routing scheme for ad hoc mobile networks based on the Bellman-Ford algorithm. It was developed by C. Perkins and P.Bhagwat in 1994. The main contribution of the algorithm was to solve the Routing Loop problem. Each entry in the routing table contains a sequence number, the sequence numbers are generally even if a link is present; else, an odd number is used. The number is generated by the destination, and the emitter needs to send out the next update with this number. Routing information is distributed between nodes by sending full dumps infrequently and smaller incremental updates more frequently.

For example the routing table of Node A in this network is
Destination Next Hop Number of Hops Sequence Number Install Time
A A 0 A 46 001000
B B 1 B 36 001200
C B 2 B 28 001500

Naturally the table contains description of all possible paths reachable by node A, along with the next hop, number of hops and sequence number.

Selection of Route
If a router receives new information, then it uses the latest sequence number. If the sequence number is the same as the one already in the table, the route with the better metric is used. Stale entries are those entries that have not been updated for a while. Such entries as well as the routes using those nodes as next hops are deleted.

DSDV was one of the early algorithms available. It is quite suitable for creating ad hoc networks with small number of nodes. Since no formal specification of this algorithm is present there is no commercial implementation of this algorithm. Many improved forms of this algorithm have been suggested.

1. DSDV requires a regular update of its routing tables, which uses up battery power and a small amount of bandwidth even when the network is idle.
2. Whenever the topology of the network changes, a new sequence number is necessary before the network re-converges; thus, DSDV is not suitable for highly dynamic networks. (As in all distance-vector protocols, this does not perturb traffic in regions of the network that are not concerned by the topology change.)

While DSDV itself does not appear to be much used today[citation needed], other protocols have used similar techniques. The best-known sequenced distance vector protocol is AODV, which, by virtue of being a reactive protocol, can use simpler sequencing heuristics. Babel is an attempt at making DSDV more robust and more efficient within the framework of proactive protocols.

1.Perkins, Charles E. and Bhagwat, Pravin (1994). "Highly Dynamic Destination-Sequenced Distance-Vector Routing (DSDV) for Mobile Computers" (pdf). Retrieved on 2006-10-20.
3..Securing the Destination-Sequenced Distance Vector Routing Protocol (S-DSDV)

Additional Research : Securing
1.Securing the Destination-Sequenced Distance Vector Routing Protocol (S-DSDV)
propose : a secure routing protocol based on DSDV, namely S-DSDV, in which, a well-behaved node can successfully detect a malicious routing update with any sequence number fraud (larger or smaller) and any distance fraud (shorter, same, or longer) provided no two nodes are in collusion.
compare : security properties and efficiency of S-DSDV with superSEAD. Our efficiency analysis shows that S-DSDV generates high network overhead, however, which can be reduced by configurable parameters.
believe : the S-DSDV overhead is justified by the enhanced security.