Factors Affecting Wireless Networking Performance

There are many factors that affect your Wireless Networking Performance that are dependent on various areas within the network itself from the technology of the devices used, the local environment the signals will travel through, the fundamental physics behind wireless transmission and more. Some of these cannot be avoided and measures must be taken to try to minimise the negative affect that these factors will have on the network performance but others can be resolved completely either though equipment upgrading or good network planning.

There are some well known factors that affect Wireless Networking performance that most people will identify easily but that does not lessen their importance when considering network planning, these are:

Obvious Factors Affecting Wireless Networking Performance

Physical Obstructions

Network Range & Distance between Devices

Wireless Network Interference

Signal Sharing



Quite Well Known Factors Affecting Wireless Networking Performance

Network Usage & Load

Poorly Deployed Antennas

Local Environment Characteristics

Spectrum Channel Limitations

Signal Reflection

Wireless Signal Restriction



Lesser Known Factors Affecting Wireless Networking Performance

Transmitter Power Limitations

Backwards Compatibility with Older Standards

Polarisation of Signal

Speed Loss Due to Wireless Overheads

Lowering Performance to Stay Connected



The Obvious Factors Affecting Wireless Networking Performance

Physical Obstructions

Wireless signals can have trouble penetrating solid objects which can be any numbers of things such as hills, buildings, single walls or even people. The more obstructions you have between the transmitter and receiver, the more chance there is that the signal strength will be affected so you should try and maintain as clearer line of site as possible. This is obviously not practical in the real world as there is nearly always something in the way but you can minimise the effect it will have by using specific frequencies available to you. As a rule, the lower the frequency, the better penetration characteristics the waves have. However, it also runs that the higher the frequency, the better the reflective capabilities of the wave, so in some cases reflecting a signal to the receiver may work better than trying to send it through objects i.e. walls.

Network Range & Distance Between Devices

The further apart the networked devices that are trying to communicate with each other are, the more the signal strength drops. This is due to way that wireless signals propagate covering a wider area as they travel further and because of this, as the signal spreads more, the weaker it becomes. The signal strength decreases, roughly, in an inverse cubic relation with respect to the distance between the two devices.

Strength = 1/Distance^3

i.e if Distance=1m then Strength=1/1^3 = 1/1 = 1

i.e if Distance=2m then Strength=1/2^3 = 1/8 = 0.125

Therefore as the distance has doubled; the signal becomes 8 times weaker.

Wireless Network Interference

Wireless Networking is becoming more and more common and therefore more wireless transmissions are being sent through the air. Signals operating at similar frequencies can cause interference with each other and have a significantly negative effect on the performance of the network. This means that more popularly used frequency bands such as the 2.4GHz unlicensed band can get severely affected by the overcrowding of wireless signals to a point where a device will not operate at an acceptable level. Other wireless technologies can cause identical interference such as mobile phones and microwave ovens that operate within the same ranges. More frequency bands are becoming available to operate in to avoid this issue such as the unlicensed 5GHz frequency band that is becoming popular. When operating in areas of high wireless network densities, it is advised that you work with businesses, operators etc. around you to avoid future interference problems.

Signal Sharing

Wireless Networks allow more than 1 person to communicate with another network source at any one time. This sharing of connection means that the more subscribers utilising the network, the more devices the access point has to try and communicate with instantaneously. The point of access has to delegate its resources to each subscriber individually per the amount of transmitting radios it operates on. Full-Duplex capable equipment can transmit and receive data simultaneously whereas Half-Duplex equipment can only send or receive at any one time.



The Quite Well Known Factors Affecting Wireless Networking Performance

Network Usage & Load

You will find that the more clients that are utilising the network bandwidth, the less that there is to share between them. As bandwidth requirements increase on your network (video streaming is one bandwidth intensive application), you may want to invest in equipment that can cater for high throughput speeds to keep the performance and network reliability at a high level.

Poorly Deployed Antennas

As antennas work by limiting the spread of transmitted signals to a specific direction or orientation, they must be installed and mounted correctly to improve network performance. The most obvious is the highly directional antenna type that must be pointed directly at the receiver in order for the signal to be picked up but other types of antenna must be orientated correctly to ensure that they are transmitting signal on the correct plane. Sector antennas usually have a vertical or horizontal plane that they operate on and Omni-Directional antennas will only transmit signal well on one plane but in all directions.

Local Environment Characteristics

Most prominently affecting indoor networks, wall construction properties can be one of the biggest inhibiters of wireless signals. Wire meshing within the walls can cripple signal transmissions and the materials used have different levels of effect; concrete is a usual suspect in badly performing indoor networks. It almost goes without saying that the thicker the walls, the less success the signal will have penetrating through it whilst maintaining a high strength.

Spectrum Channel Limitations

This typically only affects Wireless Networks that operate at only popular frequency bands such as 2.4GHz but may start to affect the 5GHz band in the future if people migrate en masse. Wireless Networks operate on frequency sub-bands know as channels that are of smaller bandwidths within their overall possible operating frequencies. The 2.4GHz band is split up into 11 channels operating on bandwidths of 25MHz each spaced 5MHz apart, within an overall range of 2412MHz to 2462MHz. It doesn't take much maths to work out that the channels have to overlap each other to be able to fit within the overall operating range. This overlapping causes interference if wireless devices are using neighbouring channels and so the only channels recommended for use are 1, 6 and 11 as these do not overlap. However, this means that only 3 wireless devices can used within the same area unless overlapping channels are to be used.

Signal Reflection

Signal reflection, known technically as Multi-Path Fade, occurs typically in buildings that have complex and intricate structural layouts. The different paths the signals take when being transmitted can be reflected off of surroundings causing differences in overall path distance lengths on their way to the receiver. When these varying signals reach the receiver they can be out of phase with each other and this can cause the overlapping waves in question to either enlarge the signal amplification or can completely cancel out each other. Also the times at which the reflected signals reach the receiver are different due to the varying distances in the RF Paths they have travelled to get there. The spread in the delay between the signals creates ISI (Intersymbol Interference) which is a situation in which the delayed signals begin to corrupt the symbols travelling on a shorter RF Path. These problems can be overcome by using diversity antennas (installing more than 1 antenna on the transmitter at specific distances apart) which ensures that if one antenna is performing poorly, the other will most likely be okay or by using technology such as OFDM which can cure this by introducing subcarrier channels within each main channel. These sub-carrier channels send and receive date simultaneously in parallel with each other and the many, smaller channels ensure that more data can be transferred with lower levels of loss due to signal interference.

Wireless Signal Restriction

For security reasons you may want to restrict the transmission of your wireless signal to only the areas that you want to provide network access for. This can be troublesome as controlling signal propagation is not easy as it can travel through walls into other buildings or outside areas where someone could try to connect without authorisation. Limiting transmitter power levels to only cover the required area is one method of solving this issue but it has the knock on effect that signal strengths will be weaker to all receiving devices. Using directional antennas to limit the signal spread can also be effective in limiting the area in which the signal covers.





Lesser Known Factors Affecting Wireless Networking Performance

Transmitter Power Limitations

Regulations set by OFCOM dictate that the devices operating on certain frequency ranges must adhere to maximum transmitter output power levels. These values change depending on what frequency your devices are operating on with, for example, 2.4GHz being 100mW E.I.R.P and 5GHz being between 200mW - 4W E.I.R.P; so you can see that for different bands, you can operate on different power levels. This has a large effect on signal strength and in most cases, networks benefit from having the devices operating on as higher power levels as regulations allow, increasing signal strength over longer distances. If directional, gain antennas are used the operating power levels may have to be turned down because OFCOM declares maximum limits to the relative signal strength produced by the radio and antenna combination. If using a highly directional, pencil beam type antenna, the radio's power levels may have to be reduced significantly to keep the wireless transmission within the maximum signal strength regulations.

Backwards Compatibility with Older Standards

Currently this is only having a major effect on networks operating on 802.11 standards. If you have a mixture of devices that are 802.11n and some that are only 802.11b or g, the new technology has to limit itself to the maximum throughput speeds of the old b and g devices. It is advised that if you want to experience the full potential of new standards of technology, you replace all existing, old devices that could restrict your network performance.

i.e.

Max Speed on 2.4GHz Network with 802.11b device present: 11Mbps

Max Speed on 2.4GHz Network with 802.11g device present & no 802.11b devices: 54Mbps

Max Speed per Stream on 2.4GHz Network with only 802.11n devices: 150Mbps

Polarisation of Signal

Antennas polarise their transmitted signals and therefore receiving devices should be orientated to receive the signal on the same plane for the optimum performance. This is essential in the installation of high throughput, mission critical, Point-to-Point Ethernet Bridge Links.

Speed Loss Due to Wireless Overheads

Due to encryption, packet translation and partial utilisation of channel bandwidth for user data, advertised throughput speeds are not the actual, real world throughput speeds experienced by the end user. Wireless networking protocol overheads typically result in maximum throughputs of half the maximum theoretical speeds advertised and this can then be further reduced by other factors relating to the makeup of the data packets. Basically, the maximum advertised speeds are in general much higher than what you will probably experience but some manufactures are listing "real world" speeds on their products to give customers a better idea at what they can expect to achieve.

Lowering Performance to Stay Connected

Some Wireless Networking devices can reduce the operating throughput speeds to devices as to remain connected in areas of low signal due to increased distance between devices or interference etc. This affects the whole network and other users connected to it because of the increased time of data transmissions between the slower devices. Also the retransmission of data because of dropped packets limits the availability of the access point for communication with other clients.

MikroTik: Configuring Radio as Bridge

Login into the radio using Winbox.

1. Click on the wireless Tab and go to Interface on the appeared window.

Enable the wireless interface and click it to bring this window up

On Mode: choose station-WDS

Station WDS- This allows you to connect to an AP that is in Wireless Distribution mode. This will allow you to do a straight bridge with multiple clients.

2.To add IP Address

Click on IP Tab to select Address

Add the IP on the ether1 interface

3. To add Gateway

Go to IP - Routes and Add Gateway on gateway place

4. Go to Bridge to add Bridge1 by clicking on + sign

Then click Ports Tab to add Wlan1 and ether1 ports on bridge1

There you go! you have configured the radio as bridge.

Mikrotik: Configuring Radio as Router

1. Login into your radio using winbox

2. On the left hand menu choose wireless then go to Interface on the window appeared.

Enable the wireless interface by selecting it and click the tick sign

Click the wireless interface to bring up the following window

Select the wireless tab

On the Mode choose Station

Station means: This is where your MTK acts as a client and connects to an Access Point

If you click on the Advanced Mode you will be able to see Radio Name with Mac Address. You can Add the name of the client. This will enable you to identify whose radio is remotely when you login into your AP.



3. Go to IP, then Address to fill in the Public IP for Wlan1 interface and Private IP for ether1 interface

4. Go to IP, Then Routes to add Gateway

The gateway you are adding here is that of Public IP

5. Go to IP, then DNS to add Domain Name Server

On the appeared window, click Settings, DNS Settings window will appear. Add your DNS IP(s)

6. To add NAT, go to IP, then Firewall. Choose NAT on the appeared window. Click the + sign, go to Action to choose Masquerading

Masquerading conserves the number of global IP Addresses required and it lets the whole network use a single IP address in its communication with the world.

7. To add DHCP Server, go to IP, then DHCP Server, click on DHCP setup. click next, next till it is done. but make sure that the DHCP Server Interface is ether1.



You are done. Congratulation for configuring the Radio as Router! :-)

Port Forwarding

Port Forwarding

For example, you are hosting a web server with port number 80 in your private network and you would like to allow anyone on the Internet to access your web server, you can follow this guide to setup the port forwarding on your MikroTik router or RouterOS device.

You can change the port number and the IP address mentioned in this guide according to your requirement.

You have to know how to login to WinBox to follow this guide and your router should get connected to the Internet to allow the access from public network.

Run WinBox and connect to your router.

Click on “IP” on the menu then click “Firewall” on the sub-menu.

Click “NAT” on top to switch to it.

Press the plus button.

Change the values as below. “In. Interface” should be filled with the interface with Internet dial-up connection or public network, like UniFi, Maxis, TIME, Streamyx or other.

Switch to “Action”.

Change the values as below. “To Addresses” should be filled with the private IP address of your web server. “To Ports” should be filled with the port number of your web server.

Press “OK” to complete.

Now your web server is accessible from the Internet!

How to convert a D-Link Router to an Access Point

To change your D-Link Router to an Access Point;

1. Go to Network Settings

2. Change the IP Address from 192.168.0.1 to 192.168.0.2

3. Disable DHCP

4. Disable DNS Relay

There you go! you have an Access Point now

Ka-band VSAT Installation

MikroTik: Router as Access Point

This is the easiest of all configurations in MikroTik. By default, the router acts as an Access Point. What you do is just make these few changes.

You can use your browser to configure it. Remember the default IP Address is 192.168.88.1.

I prefer using the WinBox.

1. Click to the Wireless Tab on the left hand side.

2. Go to Interface Tab

The mode remains as it is: Ap-bridge

on the SSID, you can change to you desired name. and that will be the name of your Wireless.

3. To put wireless security

Go on the Security Profiles

double click on the set security to rise a new window whereby you will click the general tab.

on mode, choose the dynamic key

Tick all the Authentication keys

on WPA Pre-shared key and WPA2 Pre-shared key, that is where you put your wireless security key.

4. If the router is connected to MikroTik Radio, it is wise to change the IP Address. you can put 192.168.88.2/24, the same range as the radio which will be 192.168.88.1/24.

and make sure you remove the DHCP Server and reconfigure it.



That will do it! Enjoy you wireless :-)

MikRoTik: Blocking Those Websites

The easiest way to block those unwanted sites without cracking your head with "ip firewall filter...blah blah" (i mean commands), just follow the following steps;

1. go to IP

2. Choose Firewall

3. select Firewall Rules

4. click the + sign (which means add)

5. click the chain drop down arrow to choose forward

6. on advanced tab you can write the content you want to block. e.g, google/facebook/whatever

7. the action is drop

mind you: you have to write the whole website. e.g www.facebook.com if you write only facebook, you will be blocking every page that contains the word facebook.

tell me if this was useful

Mr. Freeman and i

People like him inspire me to get creative. Maybe one day i will meet him :)

The Tech Industry’s Darkest Secret: It’s All About Age

They don’t prepare you for this in college or admit it in job interviews. The harsh reality is that if you are middle-aged, write computer code for a living, and earn a six-figure salary, you’re headed for the unemployment lines. Your market value declines as you age and it becomes harder and harder to get a job.

I know this post will provoke anger, outrage, and denial. But, sadly, this is the way things are in the tech world. It’s an “up or out” profession — like the military. And it’s as competitive as professional sports. Engineers need to be prepared.

This is not openly discussed, because employers could be accused of age discrimination. But research, such as that completed by University of California, Berkeley, professors Clair Brown and Greg Linden shows that even those with masters degrees and Ph.Ds have reason to worry.

Brown and Linden’s analysis of Bureau of Labor Statistics and Census data for the semiconductor industry revealed that although salaries increased dramatically for engineers in their 30s, these increases slowed after the age of 40. After 50, the mean salary fell by 17% for those with bachelors degrees and by 14% for those with masters degrees and Ph.Ds. And salary increases for holders of postgraduate degrees were always lower than for those with bachelor’s degrees (in other words, even Ph.D degrees didn’t provide long-term job protection).

It’s the same in the software industry. Prominent Silicon Valley investors often talk about youth being an advantage in entrepreneurship. If you look at their investment portfolios, all you see are engineers who are hardly old enough to shave. They rarely invest in people who are old.

It may be wrong, but look at this from the point of view of the employer. Why would any company pay a computer programmer with out-of-date skills a salary of say $150,000, when it can hire a fresh graduate — who has no skills — for around $60,000? Even if it spends a month training the younger worker, the company is still far ahead. The young understand new technologies better than the old do, and are like a clean slate: They will rapidly learn the latest coding methods and techniques, and they don’t carry any “technology baggage.” The older worker likely has a family and needs to leave the office by 6 p.m. The young can easily pull all-nighters.

What the tech industry often forgets is that with age comes wisdom. Older workers are usually better at following direction, mentoring, and leading. They tend to be more pragmatic and loyal, and to know the importance of being team players. And ego and arrogance usually fade with age.

During my tech days, I hired several programmers who were over 50. They were the steadiest performers and stayed with me through the most difficult times.

It can be difficult for some companies to justify paying the age premium. For tech startups in particular, it always boils down to cost: Most can’t even afford to pay $60,000 salaries, so they look for motivated, young software developers who will accept minimum wage in return for equity ownership and the opportunity to build their careers.

We can blame the employer, but in a free economy you can’t really force any company to hire workers who have the wrong skills or to pay higher salaries. Larger companies develop products for global markets and have global workforces. They will hire where they can get the best skill for the best price.

So, whether we like it or not, it’s a tough industry, and the onus is on employees to keep themselves marketable. I know that many people will take offense at what I have to say, but here is my advice to those whose hair is beginning to grey.

Move up the ladder into management, architecture, or design, and diversify your experience. Work with business executives in your company, in areas such as sales, finance, marketing/product management, legal, and operations. Develop a broader set of skills that make you more valuable to your employer and that differentiate you from others with just coding skills.

Become an entrepreneur. Despite what some investors say, older age is an advantage in the startup world. You know more about industries and markets, and have ideas for products that the world actually needs and a better ability to motivate and manage than a kid out of school does.

Keep your skills current. This means keeping up to date with the latest trends in computing, programming techniques, and languages, and adapting to change. To be writing code for a living when you’re 50, you will need to be a rock-star developer and be able to out-code the new kids on the block. Top developers are always in demand and companies will readily pay top dollars for them.

If you’re going to stay in programming, realize that the deck is stacked against you. Even though you may be highly experienced and wise, employers aren’t willing or able to pay an experienced worker twice or thrice what an entry-level worker earns. Save as much as you can when you’re in your 30s and 40s, and be prepared to earn less as you gain experience.

Finally, I don’t know of any university, including the ones I teach at, that tells its engineering students what to expect in the long term or how to manage their technical careers. Perhaps it is time to let students know what lies ahead and prepare them for their difficult careers.

By Vivek Wadhwa

When I am Up There

When I am up there, i usually hope that i won't convince myself that "I can Fly"

Girl On Fire

Yes, I created it.

RJ45 vs RJ48

Most people can easily identify between an RJ11 and an RJ45 wiring, and point out the differences and specific uses of each. But when it comes to an RJ45 and an RJ48, it becomes a little bit more difficult. This is because they usually use the same modular connector and the differences between the two are not easily identifiable. RJ which stands for registered jack does not actually identify the type of connector that is being used. Instead, it identifies the wiring that is being used. These two RJ types therefore differ only in how they are wired.

Both RJ48 and RJ45 use the 8P8C modular plug and 2 pairs of the wires, one pair for transmitting and one pair for receiving data. The RJ45 that we are already very familiar with uses the pins 1,2,3, and 6 for receiving and transmitting data. With RJ48, there are a few configurations that can be used depending on the situation and how they are to be used. One configuration uses the pins 1,2,4, and 5 while another uses 1,2,7, and 8. Other wires are also used for extra shielding while the remaining wires are reserved in case some uses would arise in the future.

RJ45 is used mainly in local area networks where the distances between each network element is relatively short. This is very common in a lot of offices and homes and is the main reason why it has become very popular. RJ48 is used in other applications, the most common one would be in T1 data lines where the wires can extend longer distances and are often exposed to the environment. To protect the integrity of the signal, RJ48 wirings use STP or Shielded Twisted Pair cables. RJ45s use the more common UTP or Unshielded Twisted Pair that have categories 1 to 6, with cat5e being the most predominantly used.

Whether RJ45 or RJ48 is to be used is dictated by the hardware. It is no longer up to the consumer to choose. Just make sure that you wire your connectors properly to what the hardware needs so that you have a working link.

Summary:
1.RJ45 and RJ48 use the same connector
2.RJ45 differs from RJ48 in the way they are wired
3.RJ45 is predominantly used in LAN while RJ48 is more commonly seen on T1 lines
4.RJ45 is connected with UTP cable while RJ48 uses STP