You can use preupgrade.

yum install preupgrade

Once preupgrade is started, tick the box that says "Display unstable test releases". If you are planning to switch to stable F-16, then the release date for F-16 is : 8 Nov, 2011.

More info here: http://fedoraproject.org/wiki/Howtouse_PreUpgrade

All the options are listed at DistributionUpgrades

In order, I would suggest:

• use the dvd, as this gets the most testing.

• use preupgrade

• use yum only if you are ready to solve your issues and understand how yum and packages work. ;)

ok i know, i won't get upvoted for this answer on yum upgrade. but here is the deal,

 yum update yum #first update your yum

 yum clean all #remove all cruft from all previous yum transactions

 yum --releasever=16 --disableplugin=presto distrosync #glorious upgrade-path

since you are upgrading from fedora 15 to fedora 16, you mightnot like it,but you have to eventually switch to grub2

  /sbin/grub2-mkconfig -o /boot/grub2/grub.cfg

and install grub2 to where you installed grub

  /sbin/grub2-install BOOTDEVICE

if you have installed grub on MBR(atleast i do)

BOOTDEVICE=/dev/sda

so this is it,if you get into trouble,well ask for help.

All this information is shamelessly stolen from Upgrading through yum

so you should probably see that link for detailed explanation,i put this info to serve as my upgrade quick-reference and for impatient noobs.

@vedvasu

yum --releasever=16 --disableplugin=presto -distrosync #glorious upgrade-path

do not work, i use:

yum upgrade --releasever=16 --disablepresto