Editing ALOHAnet (section)

=== Demand Assigned Multiple Access ===
{{main | Demand Assigned Multiple Access }}

Demand assigned multiple access (DAMA), also called reservation ALOHA, is an explicit reservation scheme often used in satellite communications.
DAMA alternates between two phases: During the reservation phase of a frame, DAMA acts like slotted ALOHA for some fixed number of short slots, except instead of ground stations sending complete packets, ground stations only send short requests for later transmission. The satellite collects all the successful requests (i.e., the ones not destroyed by collision) and sends them back as a reservation list assigning specific ground stations to specific TDM slots. During the TDM phase of a frame, the ground stations obey the reservation list and each one only transmits during the long TDM slot(s) reserved for it.
Collisions may occur during the reservation phase, but not during the TDM phase.<ref name="ppgk" /><ref>
Ramjee Prasad; Marina Ruggieri.
[https://www.google.com/books/edition/Technology_Trends_in_Wireless_Communicat/DmA0d_B8dZcC "Technology Trends in Wireless Communications"].
2003.
p. 44.
</ref>

Maximum channel efficiency for slotted ALOHA is 36%; DAMA improves maximum channel efficiency to 80%.<ref name="ppgk" />