HTW S116 - the first Solar Powered Mobile Phone

0) Install Summerboard
1) Open up SMBPrefs.
2) Tap where it says Themes.
3) Select a theme.
4) Scroll down to the bottom of the main menu in SMBPrefs and tap "Restart SpringBoard"

Installing SummerBoard themes
by http://superfluousbanter.org/

To install SummerBoard themes you can download them like an application via Installer.app, but if you have a theme of your own you can install them by SFTP.

You can download Fugu to SFTP.

Connect to your iPod Touch via SFTP, and navigate into /Library/SummerBoard/Themes where you'll see the directories of the four pre-installed themes. Once there upload your theme folder.
The path should be /Library/SummerBoard/Themes/

Now return to your iPhone’s home screen (press the “Home” button) and launch SMBPrefs, then press “Theme” and select “” (the theme we just uploaded). Press the “Home” button once more to return to your home screen and see the new theme in place.

The telescope 4 iPhone

Posted by Prerna at 10:37 PM | Sunday, August 17, 2008

The Telescope 4 iPhone

Want to have a closer view? The telescope for iPhone is attached to the included unique protective casing. You can now have a closer look on the girl live opposite you and maybe take a few shots of her.

THINK BEFORE BUYING iPhone 3G IN INDIA!!!

Posted by Prerna at 10:33 PM | Wednesday, August 13, 2008

Those of you in India planning for iPhone... THINK TWICE BEFORE MAKING A DECISION... The short comings of iPhone are endless...

No video calling,

no AD2P on the Bluetooth,

CAN'T share ANY (mp3, images,videos. ...) files via bluetooth,

can't use as a wireless modem, (you pay ridiculous data charges to activate internet on your phone, but cannot connect it to your PC and browse when you are at home)

no copy and paste,(cannot copy a part of a.... say.... email & send it....have to type it out yourself)

no 3.2 or 5 megapixel camera,(the 2MP camera it carries is worst camera i've ever seen..... photos look like they have come out of a VGA camera)

no video recording with camera,

no front camera,

no flash.

no JAVA support

No physical keyboard (BELIEVE me! this alone is a dealbreaker. ..touch keyboard as good as it looks...once you use it then only you come to know about the importance of having a hard keypad)

No 3G network yet in India..so why pay for expensive 3G phone if you cant use its 3G services ... so, for India, iPhone 2.0 is no better than its first version

No removable battery. (You cannot change battery. Have to send it to apple outlet.. Come on now!!!!...This is not an iPod. Its a bloody phone. You cannot live without phone for 2-3 days)

No haptic feedback and

cannot send MMS,

can't use as external storage device (16 GB of utter waste..next time you go to your friend's house & find some interesting songs, movies, etc...sorry you cannot connect your '16 GB' phone and share it!!!! Apple apparently has a solution.. " BUY MUSIC & MOVIES FROM iTUNES STORE "..... Give me a break will you APPLE!!!)

no FM radio,

can't use your mp3 files as ringtones,(This is heights man!!!)

cannot insert any other SIM card

completely tied to iTunes... Connect to your friend's iTunes & you risk erasing everything on your phone.

list goes on & on & on

We Indians are used to these features. Most of our phones already have these features. & we cannot do with out them.... i mean can you imagine paying so much for a phone with which you cannot transfer files via bluetooth. what age is this ...STONE AGE???

Some features may be activated by jailbreak.. But why the hell should you risk losing your warranty after paying so much.

And want to add third party softwares??. . YOU HAVE TO BUY THEM FROM iTUNES STORE ONLY!!! . (Shell out more money). Apple is a bloody control freak. Dont surrender your freedom to it.

Its good for american market (who have no idea what mobile freedom/choice is) which is in stone age compared to asian/european markets. When they want to buy a phone, they have to go to network operators and buy only those phones that are available on that network. & stick to that company till their contract expires. You want to change carriers? Not before paying damages, & buying another phone on the other network again.

On the contrary, we in India have so much freedom. We go to handset shops & buy which ever phone we like. Then go to carriers.. checkout the plans & buy SIM.. Dont like the plan or rival carrier came up with a better plan???? EASY .. just remove & replace the SIM.

Apple are trying to IMPOSE THEIR MODEL ON US riding on the hype iPhone has created in the US (yes it was a flop in Europe ..thats why Apple never talks about its sales in Europe).

Dont fall for the subsidized price of iPhone... CHECKOUT THE DATA PLAN ATTACHED TO ITS SIM ..they will recover the cost through ridiculous data plans. Bill might come to around Rs 2500/month.( ATLEAST AMERICANS PAY THAT MUCH)

Let me clear one thing though.. iphone is the best looking phone (its touch interface is nothing like you have ever seen ), & best browsing experience out there no doubt .... (& others are fast catching up..check out the android demo at Google IO 2008).... BUT AFTER A FEW DAYS IT ALL COMES DOWN TO FUNCTIONALITY. ..

Those of who buy it... You will be most happy for atmost a week... & then, MARK MY WORDS...YOU WILL START REGRETTING IT!!!

My advice...WAIT FOR HTC DREAM!! (powered by android). Still not convinced by then...by all means go for iPhone...

So friends lets spread this info to all our friends and help them in making a wise decision.... . & those of you who have bought unlocked versions already please share your experiences with others

THANKS FOR YOUR TIME.... GOODLUCK!!!

Apple iPhone Launch in India With Airtel & Vodafone

Posted by Prerna at 2:43 AM | Thursday, August 7, 2008

India soon going to use their legal i phone... two companies are coming with this i phone...
Airtel and vodaphone is in the race to launch i hpone as soon as possible...

Vodafone targetted to launch iPhone in India 15 days before Airtel would make it available but , airtel gave a shock to them by announcing their launch date of August 22nd. Now the latest report is that Vodafone has revised the launch date to August 18th which is almost 10 days from today.

iPhone Pricing for Chennai Delhi Kolkata Mumbai Hyderabad :
4 Gb Apple iPhone : 8000Rs
8 Gb Apple iPhone : 12000Rs

You can always get notified by these companies when their product launches if you subscribe to their pre-launch applications.

Book iPhone via Airtel -
http://www.airtel.in/iphone3g/#

Book iPhone via Vodafone -
http://www.vodafone.in/existingusers/iphone/pages/book-iPhone.aspx

You Can Also Book Your IPHONE Via SMS With Vodaphone - Sms Charges Rs.3
Pre-register your iPhone 3G now. sms IPHONE to 56789

CODE DIVISION MULTIPLE ACCESS

Posted by Prerna at 11:16 PM | Wednesday, August 6, 2008

CODE DIVISION MULTIPLE ACCESS

INTRODUCTION: -

Mobile communications are rapidly becoming more and more necessary for everyday activities. With so many more users to accommodate, more efficient use of bandwidth is a priority among cellular phone system operators. Equally important is the security and reliability of these calls. One solution that has been offered is a CODE DIVISION MULTIPLE ACCESS SYSTEM.

CDMA is one method for implementing a multiple access communication system. MULTIPLE ACCESS is a technique where many subscribers or local stations can share the use of the use of a communication channel at the same time or nearly so despite the fact originate from widely different locations. A channel can be thought of as merely a portion of the limited radio resource, which is temporarily allocated for a specific purpose, such as someone’s phone call. A multiple access method is a definition of how the radio spectrum is divided into channels and how the channels are allocated to the many users of the system.

Since there are multiple users transmitting over the same channel, a method must be established so that individual users will not disrupt one another. There are essentially three ways to do this.

1. FREQUENCY DIVISION MULTIPLE ACCESS

In this technique, the available bandwidth is split up into non-overlapping frequency bands and these disjoint sub bands of frequency are allocated to the different users on a continuous time basis. In order to reduce interference between users allocated adjacent channel bands, channel bands are used to act as buffer zones, as illustrated in figure(1). These guard bands are necessary because of the impossibility of achieving ideal filtering for separating the different users. It could be compared to AM or FM broadcasting radio where each station has a frequency assigned.

2. TIME DIVISION MULTIPLE ACCESS

In this technique, each user is allocated the full spectral occupancy of

The channel, but only for a short duration of time called time slot. Buffers zones are in the form of guard times are inserted between the assigned time slots. This is done to reduce interference between users by allowing for time uncertainty that arises due to system imperfections, especially in synchronization scheme.

DRAWBACKS:

In both FDMA and TDMA, only one subscriber at a time is assigned to a channel. No other conversion can access this channel until the subscriber’s call is finished or until that original call to handed off to a different channel by the system. Voice data tends to be burst in nature. So much of the time, no data is being sent over the channel. This inefficiency tends to limit the capacity of the system.

3. CODE DIVISION MULTIPLE ACCESS

The above drawbacks are overcome in this third technique in which the users are spread across both frequency and time in the same

Channel. This is a hybrid combination of FDMA and TDMA. For example, frequency hopping may be employed to ensure during each successive time slot, the frequency bands assigned to the users are recorded in random manner. During time slot 1, user 1 occupies frequency band 1, user 2 occupies frequency band 2, user 3 occupies band 3 and so on. During time slot 2, user 1 hops to frequency band 3, user 2 hops to band 1, user 3 hops to band 2, and so on. An important advantage of CDMA over FDMA and TDMA is that it can provide for secure communication.

MEANING OF CDMA:

Here, the users are spread across both frequency and time in the same channel. Here, unique digital codes, rather than separate RF frequencies or channels are used to differentiate subscribers. The codes are shared by both the mobile stations (cellular phone) and the base station, and are called “pseudo random code sequences” or “pseudo-noise code sequences”.

PN – SEQUENCE:

A PN – sequence is a periodic binary sequence with a noise like waveform that is usually generated by means of a feedback shift register. ”pseudo” word is used, as these are not real noise. These are noise like.

BASIS OF CDMA:

Basis of CDMA is the spread spectrum technology.

SPREAD SPECTRUM is a means of transmission in which the data sequence occupies a bandwidth in excess of the minimum bandwidth necessary to send it. Spread spectrum is accomplished before transmission through the use of a code that is independent of the data sequence (PN).

It can provide secure communication in hostile environment such that the transmitted signal is not easily detected or recognized by unwanted listeners. It can reject interference whether it is the unintentional interference by another user simultaneously attempting to transmit through the channel, or the intentional interference by a hostile transmitter attempting to jam the transmission. Another application is in multiple access communication in which a number of independent users can share a common channel without an external synchronizing mechanism.

TYPES OF SPREAD SPECTRUM

1. DIRECT SEQUENCE SPREAD SPECTRUM

DS sequence allows each station to transmit over the entire frequency

Spectrum all the time. Multiple simultaneous transmissions are separated using some sort of coding technique that is each user is assigned a chip sequence. The sender and receiver synchronize by the receiver locking into the chip sequence and the sender and receiver locking into the chip sequence of the sender. All the other (unsynchronized) transmission is then seen as random noise. So with CDMA each user uses the full frequency spectrum.

They employ a high speed code sequence along with the basic information being sent, to modulate their RF carriers. The high speed code sequence is used directly setting the transmitted RF bandwidth.

Binary phase shift keying (BPSK) is the most common technique used in DS system. Direct sequence is, in essence, multiplication of a more conventional communication waveform by PN sequence in the transmitter.

2. FREQUENCY HOPPING SPREAD SPECTRUM

FH – CDMA is a kind of spread spectrum technology that enables many users to share the same channel by employing a unique hopping pattern to distinguish different users’ transmission. The type of spread spectrum in which the carrier hops randomly from one frequency to another is called FH spread spectrum. A common modulation format for FH system is that of M-ary frequency shift keying (MFSK).the combination is referred to as FH/MFSK.

A major advantage of frequency hopping is that it can be implemented over a much larger frequency band than it is possible to implement DS- spreading, and the band can be noncontiguous. Another major advantage is that frequency hopping provides resistance to multiple – access interference while not requiring power control to prevent near – far problems. In DS – systems , accurate power control is crucial but becomes less effective as the carrier frequency is increased.

Frequency hopping does not cover the entire spread spectrum

Instantaneously, we are led to consider the rate at which the hops occur. So, we may identify two basic characterizations of frequency hopping.

1. Slow frequency hopping, in which the symbol rate R_s of MFSK signal is an integrator multiple of the hop rate R_h. that is, several symbols are transmitted on each frequency hop

2. Fast frequency hopping, in which the hop rate R_h is an integrator multiple of the MFSK symbol rate R_s. that is, the carrier frequency will change or hop several times during the transmission of one symbol.

Multi-Carrier CDMA system

Multi-carrier modulation (MCM) is a data transmission technique where several sub carriers are employed to transport the user’s data stream signal. Originally this technique was implemented using a bank of analogue SyQuest filters which provide a set of continuous-time orthogonal basis functions. Today using very fast and cost effective digital signal processors, multi-carrier modulation can be implemented using discrete Fourier transform (DFT) as the set of orthogonal sub carriers. This makes the technique very attractive.

Multi-Carrier Modulation (MCM) improves system capacity by making transmission more robust to frequency selective fading and enhances user spectral efficiency. The main drawbacks are:

Difficult sub carriers' synchronization in fading transmissions.
Sensitivity to frequency offset is more pronounced than for a single carrier.
Sensitivity to non-linear amplification (peak factor problem).

To gain the advantages of both schemes (CDMA & MCM), a combination known as multi-carrier CDMA (MC-CDMA) was proposed in 1993 taking after both CDMA & MCM schemes.

An MC-CDMA transmitter spreads the original data stream in the frequency domain over different sub carriers using a given spreading code. In this system the sub carriers convey the same information at one time. The MC-CDMA offers better frequency diversity to combat frequency selective fading.

Figure 1. MC-CDMA transmitter

Figure 2. Spectrum of MC-CDMA signal

The simplicity of the multi-carrier system is an important aspect in a cellular system especially for the down link receiver (mobile station). The modulation-demodula tion is done by IDFT - DFT. A wavelet-based system can be used instead of DFT for the multi-carrier modulation. Wavelet transform has a property of time-frequency multi resolution. By choosing the right wavelet function and scaling function, the system can achieve the optimum resolution according to need.

Digital communication systems can be viewed as general transmultiplexer systems, which consist of synthesis part and analysis part. The element, which plays an important role in characterization of the system, is the filter set used in both synthesis and analysis parts. The time-frequency properties of these filters, i.e. time spread and frequency spread, will determine the type of communication systems (TDMA, FDMA, CDMA, OFDM, MC-CDMA, MC-DS-CDMA).

Consequently, the key decision is how to design and optimize this set of filters according to their applications. One of the optimization results for multi-carrier systems is to use one of perfect reconstruction quadrate mirror filter (PR-QMF) types which are called discrete wavelet multi tone (DWMT). Using this DWMT system for MC-CDMA cellular system yields the following advantages:

lower inter channel interference
more robust against multipart fading
more robust against narrow band interference or jamming signal

IS-95 CDMA system

The IS-95 CDMA system is a narrow band radio system. Bandwidth is limited to 1.25 MHz and a chip rate of 1.2288 Mcps. The system is intended to provide voice and low bit rate data service using circuit-switching techniques. Data rate varies from 1.2 kbps to 9.6 kbps. Forward (base station to mobile) and reverse (mobile to base station) link structures are different and each is capable of distinctive capacity. Forward transmission is coherent and synchronous while the reverse link is asynchronous. The 'chanellisation' in each link is achieved by using 64- chip orthogonal codes, including provision for pilot, synchronization, paging, and network access. Consequently, the number of active users able to simultaneously access the network is limited by the level of interference, service provisions and the number of 'channels' available.

CDMA TECHNOLOGY IN MOBILE COMMUNICATION

Through CDMA’s application in cellular telephony is relatively new, but it is not anew technology. CDMA has been used in much military application, such as anti jamming, ranging and secure communication.

The use of CDMA for civilian radio application is novel. Commercial application became possible because of following evolutionary developments.

· Availability of very low cost, highly dense digital integrated circuits, which reduce the size, weight and cost of the subscriber station to an acceptably low level.

· Realization that optimal multiple access communication requires that all user station regulate their transmission power to the lowest that will achieve adequate signal quality.

CDMA CELLULER RADIO STATION

Cellular services are now being used every day by million of people worldwide. The number of customers requiring such services is increasing exponentially, and there is a demand for integration of a variety of multimedia services. The range of services includes short messaging, voice, data and video. Consequently, the bit rate required for the services varies widely from just 1.2 kbps for paging up to several Mbpsfor vedio transmission. Furthermore, supporting such a wide range of data rates with flexible mobility management increase network complexity dramatically.

In a cellular network, each base station assigns separate directional sector antennas or separate outputs of a phased array to cover dis joint cell sector in both the transmitting and receiving modes. Typically there are three sectors, and 2п/3 radians span each sector.

Incelluler network, the frequency- hopping pattern can be chosen so that at any given instant of time , the frequency of the users within a cell sector are all different, and hence ,the received signals are all orthogonal if the mobile transmission are properly synchronized. Exact synchronization on the forward link is possible because acommon timing is available.the switching time or guard time between frequency- hopping pulses must be large enough to ensure that neither a small synchronization error nor multi-path signals can subvert the orthogonality.

MULTI-USER INTERFERENCE IN CDMA SYSTEM

In constrat to FDMA and TDMA techniques which are frequency bandwidth limited. In CDMA system,each user data is spread by a pseudorandom code. All user then transmit in the same frequency band and are distinguished at the receiver by the user sprcific spreading code. All other signal are not despread because they use different codes. Thease signal appear as interference to the desired user because of non zero cross co-relation values between the spreading codes. As the number of user increases , the signal to interference ratio (SIR) decrease until the resulting performance is no longer acceptable.thus, this multi –user interference must be reduced to achieve higher capacities. These are the following method to reduced the multiple –access interference.

1. By reducing cross-corelation in spread spectrum system

· Spreading the signal by orthogonal codes which have zero cross co-relation. This technique is very efficient in downlink transmission, because a base station can transmit to all user simultenously and the spread synchronously at the chip level. Transmitting asynchronously in the uplink, to restore the orthogonality of the codes, the mobile user can be time-aligned by a synchronization method.

· Cancellation schemes that usually work subtracting the interference caused by other user and require a significant processing power; they are very useful specially to solve near- for problems.

2. Power control

Power control is essential on both uplink and downlink, to minimize multiple access interference. A particular problem on the uplink is to prevent the case where mobile transmitters far away from the cells base station are swamped by the interference generated by the users closer to the receiver. provided that rather than using constant power,the transmitter can be control in such a way that that the received powers from all users are roughly equal,then the benefits of spreading are realized. If the received power is controlled, then the subscriber can occupy the same spectrum.

Maximum capacity can is achieved if we adjust the power control so that the SNR is exactly what it need to be for an acceptable error rate . the sustainable capacity is proportional to the processing gain W=Ts/Tc reduced by the required SNR.

3. Capacity improvement with CDMA antenna arrays

A simple equation for the uplink capacity U of a single CDMA cell is given by:

U=1+WG/(Eb/N0) -(σ2/G)

Where the value of Eb/N0 represents that required for adequate link performance. The scaler σ2 is the background noise power and S is the received signal power for each user. Finally g is the ratio of the antenna gain for the desired user to that of interfering user in that cell. The value of G depends on the beam pattern for each user, but will roughly proportional to

The array size M.

As a result,antenna arrays can improve the capacity in two ways :

· Increasing the antenna gain G and hence the array M. this reduce the average level of interference from each user in the cell, permitting a capacity increase . however this gain factor can be reduced by user clustering in one part of the cell.

· Reducing the required Eb/N0. antenna array can provide increased space diversity at the base station , which can permit the receiver to operate at lower power signal. This increase the tolerance of the receiver to multiple access interference

MULTI-PATH FADING IN CDMA SYSTEM

Fading is a fluctuation in the received signal strength at the receiver or a random variation in the received signal is known as fading. Fading of radio waves is the undesired variation in the intensity or loudness f the waves received at the receiver .

When the multi-path components are “resolved ” by the CDMA waveform, that is, when their delays are separated by the at least the de-

Correlation time of the spreading ,then they can be separated by the dispreading correlator in the receiver . they do not interfere because each components correlate at a different delay. When the multipath components are separated by less than the correlation time, then they can not be separated in the receiver , and they do interfere with one another, leading to what is sometimes called flat fading.

FADING ON CDMA CHANNEL

Fading is different in the forward and reverse links. It also depends on the fading rate , which in turn depends on the velocity of the mobile station .

Generally fading increases the average SNR nedded for a particular rate . in the reverse link the power control will mitigate the effects of fading at low speed , at high speed it has little effect .

So we can say that in the demodulation of the CDMA signals, the different paths may be independently received, which greatly reduces the severity of the multi-path fading. However multipath fading can not be eliminatedbecause ocassionaly there may be multipath that can not be independently processed by the demodulator.

ADVANTAGES

1. Capacity increase

2. No frequency management or assignment

3. Best for micro-cell and in building system

4. Reduce average transmitted power

5. Reduces number of sites needed to support any given amount of traffic

6. Reduce deployment and operating cost because fewer cell sites are needed

7. Improves the telephone traffic capacity

8. improves the voice quality and eliminate audible and effects of multipath fading

9. Provides reliable transport mechanism for data communication, such as facsimile and internet traffic.

10. Simplifies site selection

DISADVANTAGE

1.Multi-user interference or multiple access interference( MAI)

2.Multi-path fading

3.near- for problem

CONCLUSION

CDMA is radically new concept in wireless communication.

It has gained widespread international acceptance by celluler radio system operators as an upgrde that will dremetically increase both their systems capacity and the service quality. Moreever it spread spectrum technology is both more secure , less probable to intercept and jam,highly private and offer higher trasmmission quality than TDMA because of its increase resistance to multipath distortion .

The principle type od CDMA systems are direct sequence CDMA ,frequency hopping CDMA and multicarrier CDMA . the major problem in CDMA is the multiple Access interference( MAI) which arises due the deviation of the spreading codes from perfect orthogonality . capacity of CDMA is interference limited .the obvious way to increase capacity of the CDMA is to reduce the level of interference . This is achieved by reducing cross correlation, power control and with antenna arrays.

ALL ABOUT MOBILE PHONES

HTW S116 - the first Solar Powered Mobile Phone

NOKIA BUG

[HOW TO] - Install Themes in iphone

The telescope 4 iPhone

THINK BEFORE BUYING iPhone 3G IN INDIA!!!

Apple iPhone Launch in India With Airtel & Vodafone

CODE DIVISION MULTIPLE ACCESS

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