Abstract:
IEEE 802.16 based Worldwide Interoperability for Microwave Access networks
(WiMAX) are increasingly being deployed for last hop broadband wireless access. In
order to provide the high speed access to information resources broadband technology
like WiMAX is needed. In this research we compared different uplink scheduling
algorithms of WiMAX mainly maximum carrier to interference and noise (Max C/I)
algorithm and fair share (FS) algorithm. Max C/I algorithm is a throughput maximizing
algorithm but if throughput of the network is maximized without fairness, the SS with
low CINR should be ignored and will experience starvation. Fair share (FS) scheme
provides equal number of time slots to every SS irrespective of their CINR. If fairness is
considered, providing fair share to low CINR users will require a lot of resources which
will result into low throughput of the network although it can solve the problem of
starvation.
In this research we propose a new scheme to optimize WiMAX network based on a
compromise between Max C/I and FS algorithms. We propose a new optimum scheme
which reserves some time slots for the users which are at the edges of a WiMAX cell and
these users will share equal slots among them from reserve slots. The remaining slots are
provided to other users according to Max C/I scheme. Hence this scheme optimizes
between Throughput and Fairness in WiMAX Network We also compared different
reservations schemes i.e. 30%, 40% and 50% reservation of time slots and compare
network throughput in different reservation schemes. We also analyze the behavior of
edge SS’s in different reservation schemes.
The above scheme works fine if users are distributed uniformly in WiMAX cell but
however if users are not distributed uniformly then this reserve slot percentage should be
dynamic according to edge user’s percentage. For this purpose we make this decision
dynamic i.e. BS will decide this reservation percentage on a basis of users which are at
the edges of a WiMAX cell or having low CINR value (lower modulation
