Figure 3
An example for showing the operation of Algorithm CBP over an OVSF code subtree, where the code 
refers to an OVSF code with 
and the data rate of 
, for 
. Let 
, 
, and 
. (a) The OVSF code subtree is assumed to have initially a single real-time (RT) call, namely, Call 1, that is assigned code 
. When a new non-real-time (NRT) call, namely, Call 2, requiring a code with 
is admitted to the network, there are three free codes with 
: 
, 
, and 
. Algorithm CBP determines the weights 
(lines 12–20) of the three free codes as 2, 3, and 3, respectively. Because the free codes 
and 
have the same weight 
, we need to determine their 
values to try to choose a code with a higher weight. But, their 
values happen to be the same as well and, therefore, CBP chooses 
randomly to break the tie (line 23). The initial assignments of codes to calls 3, 4, and 5 are done similarly. (b) When calls 1 and 5 experience poor channel conditions during dynamic bandwidth allocation, they are assigned the higher rate codes 
, and 
, respectively, to compensate the data rate decline due to deteriorating channel conditions.