This preview shows page 1. Sign up to view the full content.
Unformatted text preview: 41 allocation of subcarriers has been made, each user is allocated power P m to satisfy his or her minimum rate requirement given by R m as shown in Box (2). Since the function F was previously defined as the achievable data rate per subcarrier for a given SNR, F-1 gives the SNR for a given data rate per subcarrier. The calculation in Box (2) and the loop conditions in Box (3) and Box (6) further assume that the amount of power allocated to each user is proportional to the number of subcarriers that are allocated to the user. By this assumption, if the ratio of P a /N a > P max /N , more subcarriers must be allocated to users till the loop condition is satisfied. In Box (4) P m is calculated for each user and in Box (5) the user corresponding to the minimum value of P m is found. The thing to note here is that if the user m s required output rate is fixed at R m , his or her power requirement decreases when the number of subcarriers assigned to him or her is increased. Hence every time the equations in Box (4) and Box (5) are executed, the update her is increased....
View Full Document
- Spring '09