Supporting a previous version of the product - level of support

Suppose you are part of an application that has released several versions. What do you do about support for previous versions ? There is a strong temptation to set it such that most of the effort is focused towards creating great new versions for the ongoing and future versions, and if there is any support for the previous versions, a lot of that support will be focused on how to move the users to the latest version rather than really supporting them while they are using the previous version. After all, the money is to be made when users move to the latest version, and the more the support for the previous version, the more the cost of doing so.
However, this philosophy has underdone some changes in the last many years. No organization will directly accept that they do not provide good support to uses of previous versions, but at the same time, there are sizable costs associated with supporting users who are on previous versions. What are some of these costs ?

- One of these costs involve releasing patches and updates for these previous versions. When software has been developed and released, you would expect that there would be no real defects in software after it has been released, and hence there would not be the need for software patches on a regular basis. However, this is far from true. Once a software has been released, defects that were not found during the testing phase will pop up, either found by the team in the new version (but which also existed in the previous version), or found by users and affecting some of their workflows. Some of these defects would be serious enough that they need to be fixed - and in today's world where users can share problems and report lack of support by the organization on various social forum, it can be critical to continue to interact with users. As a result, the organization needs to evaluate such issues and be seen to be responsive.
And then there is the overall environment. There can be updates issued by the operating system or updates to other files that can cause problems. Once for example, an update issued by a popular anti-virus software caused some files in the application to get frozen, and that crippled a section of the software (which had been released 2 versions back). Like many such problems, these were reported by users who came across these issues (typically the users are able to see the problem, but to figure out the problem, there is a need to have some intense technical research done by the support team, sometimes backed up by the product team). If the product team allows such problems to continue on user forums without some obvious research or effort undertaken, it can lead to user dis-satisfaction. The organization could pretend that these were for previous versions of software and such problems are fixed in the latest versions, but such a defense is not easy to undertake and few users are convinced about such a reason. In fact, such a defense tends to put off users, who would think that they would also not be supported when such a problem is faced by them later on.

Read more about this complex topic in the next post on this series (TBD).

Ensuring coordination with respect to 3rd party icons such as from Facebook / Youtube .. (contd)

I wrote a post about this topic in a previous post (using icons from external services such as Facebook or Twitter). One of the unsaid conclusions from the previous post was that it is essential that such planning be done well in advance, so that one does not run into issues near the end of the schedule - tracking of such items where multiple parties are involved can be time consuming and frustrating when getting into the ending stage of a schedule. So what are some of the points to keep involved when dealing with using icons from 3rd party services such as Youtube, Facebook and Twitter:
- If you have used the icons in a previous version of the software, ensure that when you get into a new version of the software, you verify about whether there is a requirement to update the icon. If not, then it would be easiest to just ensure that you continue with the old icon.
- When you are doing some re-design on your end, and need to get a different icon, many of these have multiple icons available with different sizes also available for use. However, if none of these icons really fit into the UI of your application, things can get tricky. The terms and conditions of most of these services do not allow you to use an icon other than the ones that they have supplied, so modify your UI accordingly.
- If there are multiple products within the organization that use these services, then it would make sense to ensure that these products collaborate with each other to understand their use of these services. We had a classic case where one team had a relationship with the product manager of one of these services (through one of the team-members, and this contact helped in refining the use of some icons).
- Make sure that the legal team is well conversant with the usage of these icons (and also overall with the incorporation of connectivity with these services). Even though these services seem present everywhere, they do come with their terms and conditions, which need to be met by the products that are interacting with these services.
- Most of these services have an active development community. It is important to ensure that atleast one of the development team members is on this community since these communities are the first places to be notified when there are any change in policies of the external service provider. This is pretty important. We were connecting with one of these services, and then it turned out that there was a notification about a change in the API that was being used, and we did not know about this; when did we get to know ? When our connectivity to the service was lost.

How is security management done in home and small businesses?

As there are different kinds of networks, so there are different types of security management for them. In this article we shall talk about how security management is done in the home and small businesses. Only basic security is required for a small office or at home. On the other hand a lot of maintenance is required for large businesses and large institutions. Also here, normally used hardware and software is used when compared to the sophisticated hardware and software that is used for the prevention of spamming, hacking and other kinds of malicious attacks. Here we list some basic points for security management at home and small office:

- A basic firewall can be installed or even a unified threat management system can be used.
- A basic antivirus software will do the task if you are working in the windows environment.
- Other software that can be installed for security include anti – spyware programs. A number of anti – virus and anti – spyware software are available in the market.
- If you are using a wireless connection, you must take care to secure your system with a robust password. A number of security methods are supported by the wireless devices. so try to use the strongest of those methods such as the AES, WPA2. A wide range of devices are supported by the TKIP. But they can only be used in the cases where there is no compliance with the AES.
- While using wireless, the default SSID name of the network must be changed. Another security measure that can be taken is to disable the SSID broadcast as this is not required for the home use. This can be easily bypassed by the use of modern technology and if the attacker has some knowledge regarding how the wireless traffic can be detected.
- You can enable the MAC address filtering for keeping track of all the MAC devices that are on that network connected to your router. Even though strictly this is not a security feature, it does can be used for limiting and monitoring the DHCP address pool for the attackers by both AP association and exclusion.
- Static IP addresses can be assigned to the devices connected to the network. This is done for complementing the other security features and to make the AP less desirable to the attackers.
- The ICMP ping on the router must be disabled.
- You can even review the logs of the router and the firewall for identification of any abnormal traffic or connection if any is there.
- Passwords must be set for all the accounts.
- If you are using a windows operating system, you can create multiple accounts for the family members to limit all the activities.
- Children of the family must be given lessons about the information security.

Security management is about identifying the important assets of the user that of course includes the information assets and checking whether the policies protecting these assets are implemented properly. It is also about protecting these assets from loss. It identifies the critical assets and focuses on protecting them first. The potential threats to the system are assessed. Then measures are taken for eliminating or minimizing these threats. The security risks are managed by the virtue of the risk management principles. It involves identification of the risks, assessment of the effectiveness of the control strategies, determination of the consequences. The risks are identified by means of the impact they can have. The identified risks are classified and appropriate response is selected for each. 

What are different types of attacks that network face?

With a lack of security measures and checks in the right place, we put our data to risk of various types of attacks. Attacks are of two types namely active attacks and passive attacks. The active attacks involve altering the information with an intention of destroying or corrupting the network and the data. If you do not have a security plan in place your network and data are vulnerable to these types of attacks. In this article we discuss about few of such attacks:
- Eavesdropping: generally most of the network communications occur in a format that is very unsecure (i.e., clear text). This gives a chance to the attacker to gain access to all the available data paths in that network for interpreting or listening to the traffic. Eavesdropping on someone’s communication is referred to as snooping or sniffing. The eavesdropper gets a great chance for monitoring the whole network which has become a great cause of concern for the administrator of an enterprise.  There are services that are based up on cryptography. With a lack of strong encryption the data of these services can be read or traversed by the eavesdropper.
- Data modification: after the data has been read by the attacker or eavesdropper, altering this data is his/ her next step. Without coming to the knowledge of the receiver and the sender the data in the packet can be modified by the attacker. Even if confidentiality is not required in all the communications, it is a must that any of the messages should not get modified in the transition.
- IP address spoofing (identity spoofing): the computer’s IP address is used by most of the operating systems and the network for identifying whether an entry is valid or not. In some cases, a false assumption of the IP address is possible. This is called identity spoofing. Some special programs might be used by the attacker for constructing the IP packets that might seem to come from the systems that are inside the intranet of the corporate. After the attacker gains the access to a network having a valid IP address, he/ she might reroute, delete or modify the data.
- Attacks based up on passwords: the password based access control is a common denominator of many network security plans and operating systems. By this we mean that your user ID and password determine your access rights. Always protection to identity information is not provided by the old applications as they might be validated when passed through the network. This might give a chance to the eavesdropper who poses as an authorized user for gaining access to the data. Whenever a valid user account is found by the attacker, he/ she gets the exact rights which are possessed by the real user. Now suppose if the user is admin of the network, then attacker gets the same rights as the admin and can create accounts for subsequent use. After gaining access to an account, the attacker can get lists of the authorized users and network info. He can make changes in the configurations, routing tables and access controls of the networks and servers.
- Denial – of – service attack: this attack prevents a valid user from using the network or the computer. By means of this attack the attention of the staff can be diverted from the internal information systems so that they don’t get to know about the intrusion. In the meantime attacker can make more attacks. Invalid data can be sent to the network services or applications. He can even overload the whole network so that it shut downs. 

Ensuring coordination with respect to 3rd party icons such as from Facebook / Youtube ..

The process of software product development is a complex one, with a number of different items to manage. In addition to the many internal complexities that need to be managed (requirements / development and testing schedules, etc), there are a whole load of external dependencies that need to be managed, and the amount of complications involved in these external dependencies are greater than than those of the internal kind. One of the complications that need to be handled has increased with the usage of more and more 3rd party services. With the increasing use of social networks by people all over the world, they being Twitter, Facebook, Flickr, Google+, and numerous other social and sharing sites, life is more complicated now.
One cannot build applications without the connection with such sharing sites, but the actual logistics of getting this done can be complex. One of these areas revolve around all the icons and others used in the application. Now, for the most part, most applications with a large number of user interfaces use their own customs icons and graphics, these having been made to seem to fit with the application (in terms of the image that the application seeks to present, the customer profile that it tries to fit, as well as the functionality that is being done in the application - an application that is dealing with money or finances would have more icons that have some sort of representation of money or cash, while applications dealing with images would show more of cameras or images, etc). Another use of these custom icons is that they present the same set even if the application is installed on Windows or on the Mac (while the application system icons on these different OS's are very different).
However, when interfacing with these 3rd party icons, there needs to be careful coordination with the team that is developing the custom icons. As part of the public API's available for most of these networks, they also have a list of icons that client applications need to use, and in some cases, the icon may drastically vary from the icons used in the application. It is typically not possible to get variations in the icons provided by these 3rd party services, although some of them will provide multiple icon sets at different sizes to ensure that one of them is suitable, but that may not be the case. Further, the team designing the custom icons may not be aware that there is a legal requirement to use only the service icons, and they should be kept informed so that they do not try to develop customs icons for these networks when only the service provided icons can be used.
In addition, if the icons provided by the services are striking on their own and different from those in the application, it would help if the designer team already knows this in advance, and hence can ensure that the icon set that they are designing for the application is made in a way that the service provided icons fit with the service. But, from time to time, these 3rd party services also go in for a rebranding, and require all clients using their services to also change the icons that they are using, which means that somebody needs to keep track of communication from the external services regarding their branding and icons.

How to cope with team members (or functional teams) who do not easily follow deadlines / schedules ?

Aah, this is one of the most difficult posts to write, since there is no magic bullet answer. Let me take a situation where you have some team members or functional folks who are not really up to working with schedules, or are disciplined about schedules as the development or testing members of the team. What happens typically ? You have a schedule that has been worked out pretty diligently, that takes into account the work of different team members and functional folks, and gets them all integrated with each other to have a schedule that promises, if you follow the schedule, that you will have your software application ready.
So if everything is going well, if the project management structure of the team is tracking the schedule and the entry and exit of each of the team members as per the schedule, then everything can work out. Further, a lot can be done to help in the process, by setting up systems that provide advance schedule information to the team members, before their tasks are due to start, as well as close to when their tasks are about to end. This can be followed by status meetings and other to ensure that team members have all the information that they need to get their tasks done, and any problems that they are having can be followed up.
However, if everything went so smooth, schedules would always work and there would never be any kind of problems regarding risks, and so on. One of the biggest elements of risks in the entire schedule, just from the scope of delivery from the different functional teams is regarding adherence to the schedule. When you consider the functional requirements of the schedule, you will have requirements and feature details from the product management, followed by elements of design (architectural, workflow and others) from the development and user interface designers, and then the actual development and testing. One of the biggest problems that I have seen is with regard to the more creative elements of this process, namely the user interface designer or the workflow designer. We had an interesting interface designer who would just tell us that to give him a final date by which the entire design would be needed, and not bother about interim dates since that was not the way that he worked. There is some justification, since the user interface designers tend to be creative folks who are not really as bound to a schedule as the rest of the development and testing teams. However, this can screw up the entire schedule, since the assumption is that there are dates by which the designer needs to submit a first draft and there are iterations through which this draft is discussed, and then finally agreement is reached on the final draft to be used for the product development.
So, what do you do ? Well, here are some techniques that we used:
- Ensure that there is ongoing communication with the designer. Typically, it was during a regular phone call that we would find out about some issue that the designer was running into, but which the designer had not told us about via email.
- Remind the designer on a regular basis when the schedule for either the start of the tasks or the end of the tasks was coming up to ensure that this was on the top of the mind
- Add some buffer to the schedule of the user interface designer, and start harassing from the first schedule so that you know that you can expect to get the work by the buffer date

What happens when you find a serious defect right before you release ??

The end game of a software development schedule can be very critical. It is the timeframe when you are hoping that there are no critical problems that pop up - given that the time involved in turning around for solving critical problems is less, and the amount of tension that such a problem causes to everyone in the team can be enough to give a coronary to everybody involved. Once we had a defect come up 2 days before we were supposed to release the product, and the complications were very bad (in terms of decision making - we had to decide whether the defect needed to be taken, we had to get somebody very safe to diagnose that defect, we had to evaluate the fix to see that there was nothing else that could get broken, we had to then roll out the fix into the product and test the hell out of the fix to ensure that there was nothing that was getting broken). All of this caused a huge amount of tension, and we had management on our heads, wanting to know the progress, and more worryingly, why this defect was not caught before, and whether we were confident that we had done enough testing to ensure that we had caught all other such defects such as this one.
Typically, when you reach a situation like this, you need to ensure that you are thinking through all the options. It is all right to brazen it out and hope that everything will go well and say that you are fine with releasing the product. But, without having done a proper analysis, that would not be the correct option. If you want to get the product released in this haste, then you might be reaching a situation where user find serious defects after the product has been released, and that is something that no one wants. Such a situation, if it happens more than once, can cause loss of user confidence in the product, and to some extent in the organization, and have a lot of serious consequences. However, in most cases, I know teams tend to brazen it out even if they see much more problems later.
But, on the other hand, you cannot suddenly decide that you are willing to take a delay on the product release date to get some extra confidence of the testing (which would have been shaken due to the recent serious defect found). This sounds good, but there are costs involved with such a decision. A product delay causes a loss in revenue, also can cause some customer confidence problems if the organization suddenly has to announce a delay in release, and cause a huge impact on the team morale as well because of management involvement. However, it may be less of an impact than if the product is released and the customers find many problems.
So how do you make such a decision ? Well, that is the million dollar question. And there are no easy answers. To a large extent, whatever decision is made has a number of risks, but it is important to get genuine feedback from the testing team about what they feel, especially from the test managers (and this needs to be done in environment where there are fewer recriminations). Finally, the team manager needs to own the decision and be able to justify this in front of management.

What are uses of WiMax technology?

- The WiMax technology has been used since a long time to provide assistance to the communication process.

- This area has seen major deployment of wimax technology especially in Indonesia during the calamity of tsunami in the year of 2004. 

- The WiMax technology brought in the possibilities of providing broadband access that helped a big deal in regeneration of the communication. 

- The organizations such as FEMA and FCC (federal communications commission) felt the need of wimax in their communication process. 

- The WiMax applications with high efficiency are available today.

- It is known to offer a broad base for the customers and the services had been improved by adding mobility feature to them.

- The service providers use the WiMax technology for providing various services such as mobile and Internet access, voice, video and data. 

There are other advantages of using wimax technology.  

- You get to save a lot of prospective cost and at the same time you get efficiency in services.

- It is even capable of allowing the video making, VOIP calling and data transfers at high speeds.

- The mobile community has been upgraded so much with the coming of the WiMax technology.

- However, there are three main applications offered by WiMax namely backhaul, consumer connectivity and business.

- The real augmentation has been drawn to communications through WiMax technology because of which they can benefit both from the data transmission and video apart from voice. 

- This has facilitated quick response from the applications as per the situation.  

- A temporary communication services can be deployed by a client using WiMax technology.

- It can even speed up the network according to the circumstances and events.  

- This has got us access to visitors, employees and media on a temporary basis.  

- If we are located in the range of the tower, it is quite easy for us to gain access to the equipment of the premises of for the events.

The factors that make the wimax technology so powerful are the following:

> high bandwidth

> high quality services

> security

> deployment

> full duplex consisting of DSL

> reasonable cost

For some applications, the wimax technology is used exclusively as in the following:

1. A means of connecting for the small and medium sized businesses.  - This technology has enabled these businesses to progress day by day.

- The connectivity offered by WiMax technology is good enough to attract clients.  

- It then provides them a number of services such as that of hotspots and so on.  

- Therefore, this application has gotten into spot light.

2. Backhaul

- The most important application of the WiMax technology is the range.

- This is so because using WiMax tower can be used as a means to connect with the other WiMax towers through line-of-sight communication which involves using microwave links. 

- This connectivity between two towers is called as backhaul.  

- It is capable of covering up to 3000 miles. 

- The WiMax network is even sufficient for covering remote and rural areas.

3. The nomadic broadband is another application of wimax technology which can be considered as an extended plan of wifi.

- The access points provided by WiMax technology might be less in number but they offer very high security.  

- Many companies use the WiMax base station for the development of the business.

What are secret-key and public-key signatures?

- Asymmetric cryptography is often referred to as the public-key cryptography. 

- It is a cryptographic algorithm which makes use of two individual keys namely the secret key and the public key. 

- The secret is kept private and the public key is open. 

- Even though these two keys are different, there is some mathematical link between the two. 

- The key which is used for the encryption of the plain text and verification of the digital signature is the public key. 

- So, the private key is one that is used for the decryption of the cipher text in to plain text or for creation of a digital signature. 

- Both these keys are contrast of each other unlike in the symmetric cryptography where the same key serves both the purposes. 

- The public keys are created based up on some mathematical problems for which presently there is no efficient solution such as the following:

Ø  Elliptic curve relationships

Ø  Discrete logarithms

Ø  Integer factorization

- Generating the public and the private key pair is computationally easy for the users. 

- The strength of the public keys lies in the fact that determining the private key from its public key is computationally in feasible or almost impossible. 

- Thus, without fearing any compromise with the security, the public key can be published whereas the private key is kept hidden from everyone so as not to reveal it to anyone who does not has authorization for performing the digital signatures or reading the messages. 

- Unlike for the symmetric key algorithms, a secure initial exchange of the secret keys is not required for the public key algorithms. 

- In the process of message authentication, a private key is used for processing a message for producing the digital signature. 

- After doing so, the signature can be verified by anyone by processing the value of the signature using the corresponding public key of the signer. 

- The result is then compared with the message. 

- The unmodified nature of the message is confirmed a success signal. 

- Also, it is presumed that the private key of the signer has been kept hidden from the others. 

- However, in practical applications, the message’s digest or hash is encrypted and used as the signature. 

- The fundamental security components of the cryptosystems, protocols and applications are the public key algorithms.

These systems underpin the following internet standards:

Ø  PGP

Ø  GPG

Ø  TLS or transport layer security

- Secrecy as well as Key distribution is provided by some of the public key algorithms such as the Diffie-Hellman key exchange algorithm while some algorithms like Digital signature algorithm provide the digital signature and some others offer both the things.

- An example of such algorithm is RSA. 

- All these algorithms have been widely accepted. 

- A pair of cryptographic keys (i.e., a public key for encryption and a private key for decryption) is provided to each of the users. 

- Similarly, for digital signatures the pair of keys consists of a private key for signing and a public key for verification. 

- The concept of the private key has been introduced so as to ensure the confidentiality. 

- The digital signatures can be verified by anyone possessing the corresponding public key. 

- With such a confirmation it is confirmed the private key is possessed by the sender. 

- This is also a way to confirm that no tampering has been done to the message. 

- If the message has been tampered, it will introduce changes in the encoded message digest. 

- Mail box having a mail slot and a personal wax seal can be taken as an analogy to public – key encryption and digital signatures respectively. 

What are two fundamental cryptography principles?

In this article we shall discuss about the two fundamental principles that govern a cryptographic system. 

1. Redundancy

- Some redundancy must be there in all the encrypted messages. 

- By redundancy here, we mean the information that is not required for understanding the message reducing the chances for a passive intruder to make attacks. 

- Passive intruder attacks involve putting the stolen information to misuse without understanding it. 

- This can be more easily understood by an example of a credit card. 

- The credit card number is not alone sent over the internet rather it is accompanied by other side info such as the DOB of the card holder, its validity date and so on. 

- Including such info with the card number cuts down on the changes for making up the number. 

- Adding a good amount of redundancy prevents the active intruders from sending garbage values and then getting it verified as some valid message. 

- The recipient must be capable of determining whether the message is valid or not by  doing some inspection and simple calculation. 

- Without redundancy the attackers would simply send junk message and the recipient will decode it as a valid message. 

- However, there is a little concern also with this. 

- N number of zeroes must not be put at the beginning or the end of the message for redundancy because such messages become easy to be predicted thus facilitating the crypt analysts work.

- Instead of zeroes, a CRC polynomial can be used because it proves to be more work. 

- Using cryptographic hash might be even better.

- Redundancy has also got a role to play in quantum cryptography. 

- Some redundancy is required in the messages for the bob to determine if the message has been tampered. 

- Repetition of the message twice is a crude form of redundancy.

- If the two copies are found to be identical, the bob states that somebody is interfering with the transmission or there is a lot of noise. 

- But such repetition process to be expensive. 

- Therefore, for error detection and correction the methods used are reed Solomon and hamming codes.

2. Update

- Measures must be compulsorily taken for the prevention of the attacks by active intruders who might play back the old messages. 

- The longer an encrypted message is held by an active intruder, the more is the possibility that he can break in to it. 

- One good example of this is the UNIX password file.

- For anybody who has an account on the host, the password is accessible. 

- A copy of this file can be obtained by the intruders and they can then easily de-crypt the password.

- Also, the addition of the redundancy allows the simplification of the messages’ decryption.

- It must be checked whether the message has been sent recently or is an old one. 

- One measure for doing so is including a time stamp of few seconds in the message. 

- This message then can be saved by the recipient for that many seconds and can be used for comparing with the incoming messages and filtering the duplicates.

- Messages which exceed this time period will be rejected as being too old.

Apart from the above two principles the following are some other principles of cryptography:

Ø Authentication: For ensuring that the message was generated by the sender itself and no one else so that no outsider can claim as being the owner of the message.

Ø Integrity: In cryptography, the integrity of the messages must be preserved while sending the message from one host to another. This involves ensuring that the message is not altered on the way. Using cryptographic hash is a way to achieve this.

Ø  Non-repudiation

What is WiMax technology?

Worldwide inter-operability for microwave access or wimax is standard developed for wireless communications that has been designed so as to deliver data rates of 30-40 mbps. The update in the technology in the year 2011 upgraded the technology to provide around 1 gbps for the stations that were fixed. 

- The Wimax forum is responsible for naming the technology as Wimax. 

- This forum was formed in the year of 2001 for the promotion of the inter-operability and conformity of this standard. 

- The Wimax has been defined by the forum as the technology based up on standards that enable the last mile wireless broadband delivery as alternative for the DSL and the cable thing. 

- The IEEE 802/ 16’s interoperability implementations are referred to as the WiMax. 

- The wimax forum has ratified this family of standards. 

- By virtue of the certification provided by this forum, the vendors are able to sell mobile and fixed products that are wimax certified. 

- This is done for ensuring that a level of inter-operability is maintained at par with the other products that have been also certified for the same profile. 

- The ‘fixed wimax’ is the name given to the original IEEE 802.16 standards.

- ‘Wifi on steroids’ is the term used to refer to WiMax sometimes. 

It has got a number of applications such as in:

Ø  Broadband connections

Ø  Cellular back-haul

Ø  Hot spots and so on.

- This technology shares some similarity with the Wifi technology however, this one is more capable of transmitting data at greater distances.

It is because of its range and bandwidth that the WiMax is suitable for the following applications:

Ø  Provides services such as the IPTV services and VoIP (telecommunications services).

Ø  Provides mobile broadband connectivity that is portable across the cities and countries and that can be accessed via different kinds of devices.

Ø  Provides an alternative for DSL and cable in the form of wireless last mile broadband access.

Ø  Acts as a source of internet connectivity.

Ø  Metering and smart grids.

- This technology can be used at home for providing internet access across the countries. 

- This has also caused a rise in the market competition. 

- The WiMax is even economically feasible. 

- Mobile wimax has been used as a replacement for the technologies like CDMA, GSM that are cellular phone technologies.  

- The technology has also been used as an overlay for increasing the capacity.  

- The fixed wimax is now used for 2g, 3g and 4g networks as a wireless back-haul technology in almost all the nations whether they are developed or developing.  

- In some states of North America, this technology is provided through a numbered of copper wire line connections. 

- On the other hand, the technology is back hauled via satellites in case of the remote cellular operations.  

- While in other cases even microwave Links are used. 

- The bandwidth requirements of the WiMAX demand more substantial back-haul when compared to other legacy cellular applications. 

- In some of the cases, the sites have been aggregated by the operators by use of Wireless Technology.  

- The traffic is then introduced to the fiber networks as per the convenience.  

- The technologies that provide triple play services are directed compatible with the WiMAX.  

- These services might include multi-casting and quality of service. 

- WiMax has been widely used for providing assistance in the communications. 

- The Intel Corporation has donated the hardware for WiMax technology for assisting the FCC (federal communications commission) and FEMA etc.

- The subscribers’ stations or SS are the devices which are used for connecting to a WiMAX Network. 

- These devices might be portable such as the following:

      > Handsets and smart phones

      > PC peripheral such as USB dongles, PC Cards and so on. 

      > Embedded devices in notebooks.

What are advantages and limitations of Wi-Fi?

The Wi-Fi has its own set of advantages and limitations. 

Advantages of WiFi

- WiFi makes the deployment of local Area Networks or LANs quite cheap.  

- There are some areas where the cables cannot be installed such as in historical buildings and outdoor areas. 

- But these spaces do not have any problem in hosting a wireless LAN.  

- Wireless Network adapters are being built into almost all the laptops by the manufacturers.

- A basic level of service is provided at which different brands concerning and client network interfaces access points that are competing with each other can inter-operate. 

- The products that have been certified by Wi-Fi alliance show back word compatibility. 

- A standard device for WiFi will work at any place in the whole world unlike our phones. 

- The WPA2 or the WiFi protected access encryption is secure provided a condition that the pass phrase used is quite strong.  

- The new protocols use for WMM i.e., Quality of service increase the suitability of the Wi-Fi regarding its use in latency - sensitive applications. 

- WMM is a power saving mechanism that is used for extending the life of the battery. 

Limitations of WiFi

- Inconsistency of the operation and spectrum assignments poses a problem worldwide.  

- The range all the WiFi networks is limited. 

- A wireless access point typically uses a stock antenna having a range of 100 m outdoors and 25m indoors.

- The frequency band is a major factor for producing variations in the range.  

- The range of Wi-Fi with a 2.4 ghz frequency block is better when compared with the 5.0 ghz frequency block Wi-Fi. 

- Some wireless routers come with detachable antennas. 

- These antennas can be removed for improving the range. 

- In their place upgraded antennas can be fitted. 

- The benefit of these antennas is that they have high directional gain at the remote devices. 

- The local regulations limit the maximum amount of power that can be transmitted by a Wi-Fi. 

- The power consumption of Wi-Fi is quite higher than the other standards.  

- This is so because of the reach requirements of the wireless LAN applications.

- There are technologies available that provide a propagation range that is much shorter. 

- One such technology is Bluetooth and has very low power consumption.  

- Other technologies such as zigbee have low power consumption, a long range but provides low data rate. 

- The most commonly used wireless encryption standard is WEP or wired equivalent privacy. 

- Even this standard has been proven to be breakable even if correct configuration is used. 

- This problem was addressed by WPA or Wi-Fi protected access standard to some extent. 

- By default the wireless access points use the encryption free mode. 

- The wireless security is disabled because of which the LAN can be openly accessed. 

What are uses of Wifi?

- Routers sometimes act as a Wi-Fi access point incorporating a cable modem or a DSL modem.

- These routers are installed in buildings and homes for providing Internet access and other inter networking services to the devices that in turn are connected to a either through a cable or wireless. 

- Similarly, there are routers that are powered by battery and they consist of a Wi-Fi access point and a mobile Internet radio modem. 

- Today smartphones come with this as a built-in capability.  

- However, this feature is disabled by the carriers. 

- The carriers might charge extra money for this. 

- The standalone facilities are provided by Internet packs. 

- The places where there is no network access, wifi is used. 

- Using Wi-Fi, a direct communication link between two computers can be established.  

- There is no intermediate point.  

- This type of transmission is termed as ad hoc wifi transmission. 

- This network mode is now very popular with the multi-player game consoles. Examples are:

       > Nintendo DS

       > PlayStation portable

       > Digital cameras

       > Other consumer electronic devices.

- A citywide Wi-Fi plan has been implemented by a number of the cities around the world.  

- In India, the first city to do so was Mysore.  

- The first city in the world was Jerusalem.

- The first city in United States was Sunnyvale in California to offer city-wide wifi. 

- Another type of wifi implementation is campus-wide wifi.  

- A number of colleges in United States have set up this kind of wifi network.  

- The first university to have it was Carnegie Mellon University. 

- Using wifi, the local area Network can be deployed in very less cost.  

- There are places where it is not possible for the physical transmission medium such as cables to reach. 

- In such places wifi network is of crucial importance.  

- Also, wifi can be easily deployed in historical buildings and outdoor areas.  

- Now, because of the increasing popularity of the Wi-Fi, the manufacturers are developing Wireless Network adapters for most of the notebooks and laptops.  

- This eventually led to a fall in the price of the Wi-Fi chip set. 

- Today, the Wi-Fi chip set is economically feasible and is included in most of the devices.  

- There are many brands of client network interfaces and access-points that are competing with each other.  

- These interfaces are able to inter-operate at a basic level. 

- The Wi-Fi certification for the products is issued by wifi alliance. 

- This makes them backwards compatible with each other. 

- A standard Wi-Fi Device is supposed to work anywhere in the world. 

- The encryption standard that is considered secure is the WPA2 or wifi protected access.  

- But, this would work only if the pass phrase that is being used is strong enough. 

- The Wi-Fi has been made more suitable with the use of new protocols such as quality of service.  

- This has made wifi compatible with latency sensitive applications.  

- Nowadays, for extending battery life power saving mechanisms such as WMM are being used.  

- These are the major uses of wifi technology.

- The usage wifi has been limited because of its limited range. 

- Therefore, in order to cover up a large area several intermediate Wi-Fi access-points have to be set up. 

- The variations in the range can be produced by varying the frequency band.  

- Wifi with a small frequency block works better than wifi with a larger frequency block.

- Wifi with the larger frequency blocks are optionally used. 

- The power of wifi network can be harnessed by using high gain direction antennas instead of using detachable antennas.  

- Another factor limiting the performance of wifi transmission is the local regulations. 

- Wifi also requires high power to operate upon. 

- This is a cause of concern for the devices' batteries.