MMDS and LMDS

   

    MMDS or Multichannel Multipoint Distribution Service is a wireless broadband technology for internet access, that’s why it also known as a wireless cable. In 1970s they already used MMDS for the support of their television set by giving a clearer signal to the users. For the transmission of the signal they used terrestrial bases radio transmitters and for the receiver they only used an exclusive small digital receiver. The transmission that they used depends on the line of sight. Each of the channels can transfer in a rate of 27 Mbps and that is high enough to support the users. For the non license channel it can take a 99 MHz, 2.4 GHz and 5.7 to 5.8 GHz over the license channels. The frequency that they used is in a range belong to ultra high frequency which is 2.1 to 2.7 GHz. As the same for wired connection cable used for TV, MMDS can act the same functions. The only thing to do for MMDS to be efficient like wired cable is to boost the power that they have so that it can produce a clear signal.

     MMDS has a limited frequency spectrum. The number of channels available in RF bands characterize MMDS network. It can allocate only 200 MHz frequency spectrum, it can reduce the number of channels in the system for TV signal using 6 MHz of bandwidth, 33 channels can be fit into the spectrum. 

     The MMDS works for giving a clear signal to the users and it can accommodate many subscribers. The signal that they are using has many sources like cable head ends. Satellite, terrestrial, and cable delivered programs comprises the material to be delivered over MMDS. All satellite delivered in baseband format are remodulated and subsequently up converted to microwave frequencies. The signal that has been deliver is always passes through a heterodyne processor prior to improve MMDS frequencies. The transmission of using the antenna has arranged of about 35 miles depending on the broadcast power. Operating power is about 1 to 100 watt range. But it is a line of sight service, even if it can take too much power still it can’t support the client were living around the mountain.

     LMDS or Local Multipoint Distribution Service use to support the demands of the people for high speed broadband communication. They support them especially if they are far from the main source of signal. LMDS is also wireless technology that is used to deliver the multiple service offered in some local areas. Example services of LMDS are, voice dial up services, data, internet access, and video. LMDS operate in a higher frequency; the radio signal is limited to 5 miles of point to point service. This makes somewhat like a cellular operation in the way the carrier layout their operation.

     Benefits of using LMDS are the one reason why many local providers use this. First benefit of this is that it is very cost effective and the subscribers can easily afford it. The investors now are not afraid to invest their money upon using this system. The implementation for LMDS is also faster and not takes too much time, this is also a good factor of dealing with this system. As we all know, every one of us needs faster and reliable broadband communications. That’s why this system can help us to achieve our desire.

Reference: Broadband Telecommunication Handbook: 2^nd edition by Regis Bates

MICROWAVE AND RADIO BASED SYSTEM

    Some people not aware of microwave radio dishes placed in some areas like towers or any buildings. Microwave operates in a frequency range of 300 Mhz to 300 Ghz and its size is about 1mm and 30 cm long. Before microwave used only in telephone transmission in order to help people in their communication. But now a days microwave evolved to many purposes, like what we have seen in some residences who are using microwave in their television set.

     There are many users of microwave system; one of this is the PCS or the cellular and Personal Communication Services industry. They uses microwave in order to improve their connections of components and for the expansion of their network. Microwave also can eliminate the monthly recurring charges. But microwave played in a very crucial role in the PCS industry if their systems use the 1.9 to 2.3 GHz frequency band. The users of this frequency band are the police, fire, electric utilities, and municipal organizations. To accommodate those users in a 2 GHz frequency band, a microwave was used to relocate the users in a new band as required by the FCC.

       Second user of microwave is the CAP market or the Competitive Access Providers. They offer a large distance access in their telephone service in order to support their customers but in the lower price. CAPs uses fiber optic in their connections but they also recognize the benefits using a microwave or wireless connection.

       Microwave use for radio and TV, we can now see the growing of digital services for televisions, like signal TV. They use microwave repeaters on the satellite to retransmit TV signals to the receiving stations. It will improve the reception of the picture and give many channels that can entertain the users.

       A laptop computer with a credit card size can now uses microwave to convert the messages into binary code for computer processing and convert back to microwave for transmission. It can be use as LAN in some areas like school campuses, airports and etc., microwave make this all possible.

      In using microwave always consider the bandwidth; use only the desire bandwidth that is enough to support your system. Remember that the higher the bandwidth that you are using the bigger the cost, that’s why don’t use bandwidth that is more than enough because some of this bandwidth would be wasted. You will notice if your bandwidth is enough if your data is keep moving and voice call coming is properly manage by your system.

    If you are using microwave you need to know if it is reliable or not because it can waste your time or even your money. Make sure that it is fast in terms of transmitting or receiving so that the delay during your work will be reduce.

Reference: Broadband Telecommunication handbook: second edition by Regis Bates.

xDSL: CHAPTER 16

Internet accesses before using ILEC or Incumbent Local Exchange Carriers has many problems including the ability of maintaining and preserving their installed base. ILEC want to have high speed communication ability and more correct internet access. That’s why they continue to find way to have a new technology that can solve their problem. ILEC have an installed base of unshielded twisted pair in the local loop, and because of this they invented a new technology called xDSL in order to exist the copper cable plant. DSL is known as digital subscriber line, the lower X stands for many variations. Those variations including the following, Asymmetrical DSL, ISDN or ISDL, High-bit rate DSL, Consumer DSL, Single High speed DSL, Rate-adaptive DSL, Very high- bit rate DSL, single DSL. But the most popular on variation is the Asymmetrical DSL because it supports the cable plant and it has a speed that varies depending on the quality of copper.

ADSL produced a high speed transmission using the twisted pair telephone lines and under the current technology it uses the speed between 1.5 to 6 Mbps. They said that in the future the ADSL will carry the speed of 8.192 Mbps and it is very possible to happen. The services that DSL provides are voice, multimedia, data, video, and internet streaming protocol service.

 ISDL or ISDN_DSL is a technique that uses digital and operating at two channels of 64 Kbps for voice or non voice and 16 Kbps for data channel for signaling, control and data packets. ISDN couldn’t catch faster but it is demandable because the carriers caught off- guard when users demand was moderate, escalated so quickly. 

HDSL is developed as more efficient way of transmitting; it does not require the repeater on a local loop above 12K. HSDL is more efficient because the bridge taps will not bother the service and the splices are left in place. It can deliver 1.544 Mbps.

SDSL provides a high speed communications using a single cable pair and a distance of not greater than 10K. Despite of this distance, SDSL can deliver a 1.544 Mbps on a single cable pair. Still it has an advantage to produce a god communication. The limitation of the distance of SDSL is now supported by the use of ADSL. Now the distance becomes 18K by the help of ADSL.

RADSL is made to develop the variations and speed of transmission. IT gives the flexibility to adopt the changing in each direction during the transmission. It can also provides 768 Kbps, that’s why ILEC used this.

CDSL provide only 1 Mbps in download direction and 160 Kbps for upward direction. But still the consumers want to use this because it does not need any splitter on the line.

SHDSL supports the repeaters which further increase the reach capability of some technologies. One of the advantage of SHDSL is that is has an increasing symmetrical bandwidth during installation. SHDL provides the services to the remote LAN access, Web-hosting, application sharing, and video conferencing.

VDSL is faster and more reliable to used, obviously we know that it is fast because the name of very high bit rate. It uses a fiber feed to deliver VDSL so that they can achieve the speed that they want.

Now we know how important those variation in providing the DSL to reach their goal and to satisfy the ILECs for the improvement of their technological device so it can carry the needs of the consumers or the end users. Fast and safe communication is the most important thing that the users needed, the secondary is the cost. That’s why this xDSL made in order to give what they want.

Reference: Broadband Telecommunication Handbook: 2^nd edition by Regis Bates

Asynchronous Transfer Mode (ATM)

ATM is an evolution from many other set of protocol, it is member of the fast packet switching family and this is what we call cell relay. It is called asynchronous because it is designed to carry any form of traffic and enables the traffic to be delivered asynchronously to the network. When traffic in the form of cells arrives, the cells are mapped into the network and transported to the next destinations.

They are using a combination of TDM or time division multiplexing with cells using reassigned slots and statistical TDM if there is no cells arrive. It uses virtual circuits, the permanent virtual circuit (PVC) and switched virtual circuits (SVC) to handle the connection. These two circuits are important factor for ATM because it will fix the size of cells employed and carry the traffic of the end users.

ATM also used to integrate voice, data, video and multimedia traffic on a single backbone network. The standards of voice, video and data have different standards and their data network is also separated when it is transmitted.

ATM gives excitement to the users because it has a higher bandwidth that can support their systems to overcome the problems that they encountered from the past technology. Obviously the capacity of ATM to give a good performance to the multimedia application is much different from the technique that they are using before because it is capable of higher bandwidth.

The speed of ATM at the start of using this is about 1.544 Mbps, today it already have 622 Mbps. As we observe the difference of the two is very far, the increased of the speed is now enough to convince the user to use ATM. But even the speed increased to much higher capability, they still find ways to reach 2.488Gbps for the future application. In order to inform the people that they reach their demands in using ATM is done by QoS capability.

For layer architecture ATM is different from the OSI, ATM only uses two layer. The two layers are the data link layer and the physical layer. ATM is said to be designed to run on a physical medium such as SONET.

We need to know the importance of ATM because it gives many benefits to the users. One of these benefits is the high speed communication, this is very important so that the needs and wants of the users will easily serve. To get this high sped communication the fast hardware-base switching is also very important because the proper switching help to increase the speed of communication.

The disadvantage of ATM is that it can cause much confusion because of their name, it is called asynchronous but it is related to synchronous transmission and their specification has similarities. It needs also many protocol points and interfacing so that it can support the older legacy system.

Reference: Broadband Telecommunication Handbook: 2^nd edition by Regis Bates

Frame Relay

Chapter 11: FRAME RELAY

In data communication, carriers are not really aware for proper data transmission; they prioritize only their sales not knowing that the first most important thing to manage is the transmission of data. Now the frame relay exists in order to improve the data communication in terms of switching and transmitting of data. It can improve the data communication because it has a higher bandwidth that is enough to carry the customer services. The customers can actually demand if they want a higher bandwidth so that they can improve their system. That’s why very important that we know how to manage and used frame relay.

Mostly in our data communication we encountered problems especially during the transmission. The problem like errors, delay and etc. will occur. To lessen this problem the frame relay also is a good solution for this because it uses a high speed communication and low delay networking. They are using fast packet to reduce delay, overhead and even the cost of service has been reduce. Like for example in our project, there is always problem occurs. That’s why we need to find a solution so that the problem is minimizing. The same for the frame relay it will lessen the problems that occur.

The frame relay used in the means of helping the system to send data in a high speed transmission. It has a speed of about 56Kbps-50Mbps for transmitting data. The speed is a very big factor to consider in order to satisfy the clients, and also the clients can do their task easily using the system. And to access the high speed communication they used devices like FRAD or frame relay access devices. I can compare this matter in our personal thinking, if we have delay in our thinking it’s very difficult for us to move forward and do what we want to do. That’s why speed is very important especially in our communication systems.

During the implementation of frame relay their desire was to carry data over Wide Area Network. For this implementation they used revise version of data link protocol. They used this for the efficiency of transmitting, because it will carry the traffic during the operation. This is efficient because error has been eliminated. As we all know efficiency is one of the important things to be considered especially during implementation because it is the basis of the end users to choose what is right for them.

All of this benefits coming from the help of frame relay helps me to really understand how important fast and efficient communication is. All of us communicating always, but we do not consider the fact that this will not happen if proper data communication are not implemented. That’s why we need to know first how to handle data transmission before anything else, like voice processing, because proper data transmission is the most important part of communication.

Source: Broadband Telecommunication Handbook by Regis Bates