 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| – |
in
an ideal, noiseless channel, the capacity (i.e., the
|
|
|
number
of stations) can be made arbitrarily large
|
|
|
| – |
however,
having all chip sequences synchronized in
|
|
|
|
time
is impossible
|
|
|
|
n |
receiver
has to synchronize with sender by having sender send
|
|
|
long
enough known chip sequence that receiver can lock into
|
|
|
|
n |
all
other (unsynchronized) transmissions will appear as random
|
|
noise,
requiring larger chip sequences
|
|
|
| – |
implicit
assumption so far was that power level of all
|
|
|
|
senders
are same as perceived by receiver
|
|
|
|
n |
in
mobile environment, power of received signal depends on
|
|
|
distance
between mobile and base station
|
|
|
|
n |
requires
power management (typically by base station)
|
|
