Why smaller spreading factor can achieve higher data rate

Think about the definition of spreading factor: the number of chips for each symbol.
Remember that a chip duration is fixed.
What is symbol? Each symbol can represent some amount of bits. e.g., QPSK, each symbol represents 2 bits.

SF: 2SF vs. 512SF
Time: 2*delta vs. 512*delta
Data: 1 symbol vs. 1 symbol

where delta is chip duration.

With 2SF, you are sending symbol fast (my wife cooks very fast, so she can make lots of food)
With 512SF, you are sending symbol slow (I cook very slow, so I can can make less amount of food than my wife)

1 Comment »

  1. hi
    seems that your major research area is mobile communication (more precisely Channle and source coding + UMTS ). That sounds cool. We want to offer you the role of an author for the blog wirelesscafe.wordpress.com something about wireless cafe, this blog doesnt belong to one individual , the aim of the blog is to bring researchers on one common platform and to discuss issues related to research (and not the spoon feeding tutorial) coz one can find tutorial on many other sites, here one can discuss the implemenatation and some common misconception type of things, as you are doing on your blog.
    on becoming the author you will get full rights to access the blog.

    also one more thing, we guys believe in Human Knowledge belongs to ALL (taken from the movie antitrust)
    Feel free to revert back and ask.
    for referece you can visit http://www.wirelesscafe.wordpress.com and also on google groups and for inspiration and motivation you can visit http://www.3g4g.co.uk (blog)

    Hope to see you soon in the team. for queries feel free to drop a mail
    Cheers !
    Wireless Cafe Team

RSS feed for comments on this post · TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.