ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

MIMO OFDM Technology Tutorial and Systems

Updated on May 24, 2012
Click thumbnail to view full-size
MIMO OFDM system
MIMO OFDM system
MIMO OFDM system

What is MIMO-The full form of MIMO is multi input and multi output where signals are transmitted via multiple antennas instead of only one antenna like FDM. This technique has the potential of dramatic increase of data transmission in wireless environment.

What is OFDM- it is a combination of both modulation and multiplexing. Unlike general multiplexing technique it is applied to only one independent channel, where a set of signals from the same source is divided or spitted into a number of independent channels (sub-set of the main signals) and each modulated by separate carrier, and then multiplexed into an OFDM signal for transmission. Each independent sub-set channel can be multiplexed either by frequency or code division multiplexing.

Characteristics of OFDM sub-channels

As I already mentioned that OFDM is a special set of FDM, but what makes it special is the orthogonality of the sub-carries. That means each sub-channel of the main signal in fact multiplied by a carrier which is orthogonal to each other. Carriers are nothing but sine or cosine wave; and the area under one sine and one cosine wave is simply zero. Orthogonal carrier means if the first carrier frequency is f1 the second carrier will be 2xf1, the third carrier will be 3xf1, and so on. This kind of orthogonality of the carriers allows simultaneous transmission of sub-carriers in a tightly spaced bandwidth without interfering from each other because each carrier is orthogonal to each other making the result of their multiplication a zero. Normally, OFDM signals are sent via one transmitting antenna.

Multiplexing-mulplexing is a method of sharing bandwidth with some other independent communication data channels.

MIMO-OFDM definition-when generated OFDM signal is transmitted through a number of antennas in order to achieve diversity or cap any gain (higher transmission rate) then it is known as MIMO-OFDM

different types of multiplexing techniques
different types of multiplexing techniques
MIMO antenna
MIMO antenna

How MIMO-OFDM Works? Like any other communication systems MIMO-OFDM system also has transmitter and receiver, but it has multiple antennas -both at transmit and receive end. MIMO system can be implemented in various ways. If we need to take the diversity as an advantage to combat fading then we need to send the same signals through various MIMO antennas and at the receiving end all the signals received by MIMO antennas will receive the same signals traveled through various path. In this case the entire received signal must pass through un-correlated channels. If we are inserted to use MIMO for capacity increase then we can send different set of data (not the same set of data like diversity MIMO) via a number of antennas and the same number of antennas will receive the signals in the receiving end. For MIMO to be efficient antenna spacing need to be done very carefully- at least half the wavelength of the transmitting signal.




 Throughput of MIMO-OFDM system
Throughput of MIMO-OFDM system

Advantage of MIMO-OFDM

  • Less interference
  • Diversity gain
  • Increase data capacity
  • Power efficiency
  • Bandwidth gain

MIMO_OFDM research Universities

  • University of Southampton
  • Rich University
  • University of York
  • University of Maryland
  • National Tsing Hua University
  • Korean Institute of Advanced Science and Technology

Limitations of MIMO-OFDM

  • Antenna spacing must be appropriate depending on the type of channels
  • Very complex transmitter and receiver

MIMO-OFDM Research ideas

  • Application of CMDA in MIMO-OFDM
  • OFDMA
  • Adaptive MIMO antenna selection algorithms.
  • Frequency hopping in the presence of frequency selective channels.
  • Noise torelance and interference cancellation
  • MIMO channel estimation technique developments

working

This website uses cookies

As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://corp.maven.io/privacy-policy

Show Details
Necessary
HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
LoginThis is necessary to sign in to the HubPages Service.
Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
AkismetThis is used to detect comment spam. (Privacy Policy)
HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
Features
Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
MavenThis supports the Maven widget and search functionality. (Privacy Policy)
Marketing
Google AdSenseThis is an ad network. (Privacy Policy)
Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
Index ExchangeThis is an ad network. (Privacy Policy)
SovrnThis is an ad network. (Privacy Policy)
Facebook AdsThis is an ad network. (Privacy Policy)
Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
AppNexusThis is an ad network. (Privacy Policy)
OpenxThis is an ad network. (Privacy Policy)
Rubicon ProjectThis is an ad network. (Privacy Policy)
TripleLiftThis is an ad network. (Privacy Policy)
Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
Statistics
Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
ClickscoThis is a data management platform studying reader behavior (Privacy Policy)