قارن الطرق

	بروتوكول الوصول العشوائي ALOHA المشقوق	Shannon Capacity
المجال	الاتصالات	الاتصالات
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	1970	1948
صاحب الطريقة	Norman Abramson and Lawrence Roberts	Claude Shannon
النوع	random access protocol	fundamental theoretical bound
المصدر التأسيسي	Roberts, L. G. (1975). ALOHA packet system with and without slots and capture. ACM SIGCOMM Computer Communication Review, 5(2), 28-42.	Shannon, C. E. (1948). A mathematical theory of communication. Bell System Technical Journal, 27(3), 379-423.
الأسماء البديلة	random access, medium access	channel capacity, information theory bound
ذات صلة	3	5
الملخص	Slotted ALOHA is a fundamental random access protocol enabling multiple devices to share a wireless channel without centralized coordination. Introduced by Abramson (1970) and refined by Roberts (1975), it divides time into fixed slots and allows devices to transmit at the beginning of a slot with a fixed probability. While simple and elegant, Slotted ALOHA achieves only 37% channel utilization under saturation (optimal traffic load), a fundamental limit discovered by Abramson. Despite this limitation, Slotted ALOHA remains a teaching tool and appears in modern systems like satellite and IoT networks.	Shannon's channel capacity theorem, published in 1948, establishes the maximum rate at which information can be reliably transmitted over a noisy channel. Expressed as C = B log2(1 + S/N) for additive white Gaussian noise (AWGN), it is a fundamental bound in information theory and communications engineering. Shannon proved that reliable communication is possible at any rate below capacity, and impossible above it. This theorem underpins the design of all modern communication systems and motivates coding theory, modulation, and signal processing techniques.