A fixed banner for mobile devices is a banner which won't move from the bottom part of the website, and will always be visible for your visitors. This has the advantage of increased impressions and CTR. To create a fixed banner for your mobile site, add this code right after <body>, and in the middle, insert the Google Adsense code:
<div style='bottom:0;position:fixed;width:100%;'>
<!--insert the Google Adsense code, right here-->
</div>
