Suboptimal Rate Adaptive Resource Allocation for Downlink OFDMA Systems

Algorithm 1

(i) Initialization

  𝑐_𝑘,𝑛=0,∀𝑘,𝑛

  𝑅_𝑘=0,∀𝑘

  𝐴={1,2,…,𝑁},

  𝐴^∗=∅,

  𝑁^∗=∑^𝐾_𝑘=1𝑁_𝑘

  𝑈={1,2,…,𝐾}

 Sort all the subcarriers 𝑁 for all the users 𝐾.

(ii) Subcarrier Allocation

  (a) for 𝑚=1 to 𝑁^∗

   𝑉_𝑘=((∑^𝑁_𝑛=1𝐻_𝑘,𝑛)²/𝑁∑^𝑁_𝑛=1𝐻²_𝑘,𝑛)∀𝑛∈𝐴 /sensitivity parameter is calculated/updated for each user;

   𝑘=argmin𝑉_𝑘,(if𝑁_𝑘>0)         /the critical user is found;

   𝑛=argmax_𝑛∈𝐴𝐻_𝑘,𝑛,             /the best available subchannel is found and allocated;

   𝑐_𝑘,𝑛=1,𝑁_𝑘=𝑁_𝑘−1,

   𝐴=𝐴−{𝑛}and𝐴^∗=𝐴^∗∪{𝑛},      /the subchannel is eliminated from the set;

   𝑅_𝑘=𝑅_𝑘+(𝐵/𝑁)log₂(1+𝛾_𝑘,𝑛).       /the rate is updated;

 (b) while 𝐴≠∅

 Scenario 1:

   𝑘=argmin(𝑅_𝑘/𝛼_𝑘),

   𝑛=argmax_𝑛∈𝐴𝐻_𝑘,𝑛,

   𝑐_𝑘,𝑛=1,𝑁_𝑘=𝑁_𝑘+1,

   𝐴=𝐴−{𝑛}and𝐴^∗=𝐴^∗∪{𝑛},

   𝑅_𝑘=𝑅_𝑘+(𝐵/𝑁)log₂(1+𝛾_𝑘,𝑛).

 Scenario 2:

   for𝑛=1to(𝑁−𝑁^∗)

   𝑘=argmax_𝑘∈𝑈𝐻_𝑘,𝑛,

   𝑐_𝑘,𝑛=1,𝑁_𝑘=𝑁_𝑘+1,

   𝑅_𝑘=𝑅_𝑘+(𝐵/𝑁)log₂(1+𝛾_𝑘,𝑛),

   𝑈=𝑈−{𝑘}.

end