Xidian Univ. 随机多址接入协议 Objectives Small delay in light traffic Bounded delay for a large (pos- sibly infinite)number of users. User A User C User B Broadband Wireless Communications Laboratory,Xidian University Broadband Wireless Communications Laboratory, Xidian University 4 BWC Xidian Univ. ≈ ~ ≈ ~ ≈ ~ ≈ ~ ≈ ~ ≈ ~ ≈ ~ ≈ ~ ≈ ~ ≈ ~ ≈ ~ ≈~ ≈ ~ ≈ 随机多址接入协议