home
NEWS       BLOGS       FORUMS       NEWSLETTERS       RESEARCH       EVENTS       DIGITAL LIBRARY       CAREERS  
Network Computing Network Computing Powered by InformationWeek Business Technology Network

IMMERSE YOURSELF:

SOA

  |

Data Center

  |

802.11n

  |

Data Privacy

  |
APO  |

Virtualization

  |

NAC

  |

Security

  |

Network Mgmt

  |

Enterprise Apps

  |

Storage & Servers



Netdesign Manual

Part 2

Wireless Broadband Networks Handbook: 3G, LMDS & Wireless Internet

Chapter 7: Local Multipoint Distribution Service (LMDS) Design Technology


November 19, 2001


Brought to you by:





Check It Out!

Wireless Broadband Networks Handbook: 3G, LMDS & Wireless Internet

Copyright© - The McGraw-Hill Companies, Inc.

Read part 1

Read part 3

Read part 4




Performance

This part of the chapter presents actual measurement results showing the performance of DECT when combined with LMDS radio equipment. The goal of the experiment is to study the actual BER performance and frequency tolerance of the integrated system. Figure 7-15 shows the setup for the reference experiments, which consist of connecting the DECT modulator and demodulator back to back without going through the LMDS system.27 The BER analyzer generates pseudorandom data. The data from the BER analyzer are modulated and then subsequently demodulated by the DECT demodulator. The demodulated data are then fed back to the BER analyzer. Figure 7-16 shows BER versus frequency offset over selected received power levels.28 As expected, it can be seen that frequency offset tolerance is higher for a higher received power level. For voice applications, a BER of better than 10-3 is appropriate. Figure 7-16 shows that the frequency tolerance ranges from 30 kHz at a received power of -69.3 dBm to approximately 100 kHz at received power of -57.3 dBm. This result indicates that an expensive frequency drift compensation circuit is not needed.



In addition to the frequency tolerance measurements, you also should verify the performance of DECT after it has been integrated into the LMDS system. In particular, you should verify that indeed the special frequency drift compensation circuit is not needed. Figure 7-17 shows block diagrams for the downstream and upstream paths for the integrated system, respectively.29 These block diagrams are simply the reference block diagrams (see Figure 7-14) added to the appropriate frequency translators for downstream and upstream operations. The LMDS mm/rf system employs a free-running DRO with no phase lock loop to covert signal to/from the LMDS frequency band. Figure 7-18 shows the BER performance of the integrated system for various values of Eb/No.30 The reference curves are obtained using the reference setup in Figure 7-14. It was found that the performance degradation is acceptable. There were 3 and 4.25 dB of degradation at a BER of 10-6 for the downstream and upstream paths, respectively.





An approach to provide telephony over LMDS was presented in this part of the chapter. The telephony solution is designed using current PCS technology. A product based on the European DECT standard was presented. The advantage of the proposed telephony solution is that by using DECT or other existing PCS technology, the cost of product development and time to market can be reduced. In addition, the LMDS architecture effectively can extend the range of existing PCS systems while integrating them to a wireless broadband infrastructure. A service provider therefore potentially can reduce infrastructure cost by using only one tall antenna tower at the headend to deliver integrated services (telephony, high-speed data, and video) to customers within a 2-km radius at the LMDS frequency band as opposed to delivering only voice services at the PCS band using several other antenna towers.

LMDS/LMCS Market Drivers

Since completion of the FCC spectrum auctions, local multipoint distribution services (LMDS) have been proposed for the delivery of a wide range of services. A point-to-multipoint radio access system is capable of providing services ranging from voice to high-speed data (up to 155 Mbps) and serving customers ranging from small to large businesses. In this brief overview, let's take a look at the LMDS market drivers, where it can satisfy a market need, the characteristics of the market, and its impact on the technology.

LMDS: A Transport System

As mentioned previously, LMDS differs from ordinary transport systems in the way a train differs from a pipeline. Both are transport systems, but a pipeline can transport only one product from one place to another. A train, on the other hand, can transport many different products over the same infrastructure. LMDS, implemented with a multiservice protocol such as Asynchronous Transfer Mode (ATM), can transport, among others, voice, Internet, ethernet, video, computer files, and transaction data.

It is the multipoint radio technology, combined with the appropriate protocol and access method, that gives LMDS the tremendous potential to transform society. With transport technologies such as fiber in place, how can a newcomer compete? LMDS has some overwhelming advantages: reliability; as a transport system, LMDS can be engineered to provide 99.999 percent availability, rivaling that of the best fiber backbones; and speed of deployment. Once a hub is installed (a matter of days), new customers can be added in a matter of hours, future proof that LMDS provides data rates from T1 to OC-3c per user interface.

Managed Investment

An LMDS hub can provide service to all buildings visible from the hub site. Physical technologies such as copper or fiber require individual rights of way to each building, as well as physical placement of the transport medium.


PAGE: 1 | 2 | 3 | 4 | NEXT PAGE
 





Ready to take that job and shove it?

Function:

Keyword(s):

State:
SPONSOR
RECENT JOB POSTINGS
CAREER NEWS
Go beyond Google and get vertical. These specialized search sites will help you find the business information you need -- fast.

Ari Balogh was named to the post of chief technology officer as the companys for a "realignment" of employees.










InformationWeek U.S. IT Salary Survey 2008
Salaries for business technology professionals are falling. Here's what you need to know in order to make good hiring decisions and personal career choices. Download Today
 
ROLLING RIGHT ALONG
Follow key Network Computing Reviews from conception to completion. This Week: Holistic APM.



Network Computing Reports Emerging Enterprise Podcast Series: Secrets to Success








TechSearch


Microsite of the Week


Powerful Information at Your Fingertips



InformationWeek Business Technology Network
InformationWeekInformationWeek 500InformationWeek 500 ConferenceInformationWeek AnalyticsInformationWeek CIO
InformationWeek EventsInformationWeek ReportsInformationWeek MagazinebMightyByte and SwitchDark Reading
Digital LibraryIntelligent EnterpriseInternet EvolutionNetwork ComputingNo Jitter
space
Techweb Events Network
InteropVoiceConWeb 2.0 ExpoWeb 2.0 SummitEnterprise 2.0 ConferenceMobile Business ExpoSoftware ConferenceCSI - Computer Security Institute
Black HatGTECEnergy CampMashup CampStartup Camp
space
Light Reading Communications Network
Light ReadingLight Reading EuropeUnstrungLight Reading's Cable Digital NewsConstantinopleInternet Evolution
Heavy ReadingLight Reading Live!Light Reading InsiderEthernet ExpoOptical ExpoTeleco TVTower Technology Summit
space
Financial Technology Network
Advanced TradingBank Systems & TechnologyInsurance & TechnologyWall Street & TechnologyAccelerating Wall StreetBank Systems & Technology Executive SummitBuyside Trading SummitInsurance & Technology Executive Summit
space
Microsoft Technology Network
MSDN MagazineTechNetThe Architecture Journal
space
App Infrastructure   |   Messaging & Collaboration   |   Network & Systems Mgmt   |   Network Infrastructure   |   Security  |   Storage & Servers   |   Wireless   |   Enterprise Apps
About Us  |  Contact Us  |  Site Map  |  Technology Marketing Solutions  |  Advertising Contacts  |   Briefing Centers
Copyright © 2008  United Business Media LLC  |  Privacy Statement  |  Terms of Service  |  Your California Privacy Rights