سعة الاتصال

في شبكات الحاسوب وعلوم الحاسوب،سعة الاتصال bandwidth،^[1] سعة اتصال الشبكة network bandwidth،^[2] حجم تدفق البيانات data bandwidth،^[3] أو سعة الاتصال الرقمية digital bandwidth،^[4]^[5] مصطلحات تستخدم للإشارة إلى القياسات المختلفة لمعدل البت، التي تدل على موارد بيانات الاتصالات المتااحة أو المستهلكة مقدرة بالبت لكل ثانية (بت/ث، كيلوبت/ث، ميگابت/ث، گيگابت/ث).

مع ملاحظة أن في الكتب الدراسية الخاصة بمعالجة الإشارة، الاتصالات اللاسلكية، مودم نقل البيانات، الاتصالات الرقمية، الإلكترونيات، تستخدم كلمة 'سعة الاتصال' للإشارة إلى للعرض المحزم التناظري الذي يقاس بالهرتز.

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قدرة سعة اتصال الشبكة

Bandwidth sometimes defines the net bit rate (aka. peak bit rate, information rate or physical layer useful bit rate), channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwidth tests measure the maximum throughput of a computer network. The reason for this usage is that according to Hartley's law, the maximum data rate of a physical communication link is proportional to its bandwidth in hertz, which is sometimes called frequency bandwidth, spectral bandwidth, RF bandwidth, signal bandwidth or analog bandwidth.

استهلاك سعة اتصال الشبكة

Bandwidth in bit/s may also refer to consumed bandwidth, corresponding to achieved throughput or goodput, i.e., the average rate of successful data transfer through a communication path. This sense applies to concepts and technologies such as bandwidth shaping, bandwidth management, bandwidth throttling, bandwidth cap, bandwidth allocation (for example bandwidth allocation protocol and dynamic bandwidth allocation), etc. A bit stream's bandwidth is proportional to the average consumed signal bandwidth in Hertz (the average spectral bandwidth of the analog signal representing the bit stream) during a studied time interval.

Channel bandwidth may be confused with data throughput. A channel with x bps may not necessarily transmit data at x rate, since protocols, encryption, and other factors can add appreciable overhead. For instance, a lot of internet traffic uses the transmission control protocol (TCP) which requires a three-way handshake for each transaction, which, though in many modern implementations is efficient, does add significant overhead compared to simpler protocols. In general, for any effective digital communication, a framing protocol is needed; overhead and effective throughput depends on implementation. Actual throughput is less than or equal to the actual channel capacity plus implementation overhead.

سعة الاتصال المقاربة

The asymptotic bandwidth (formally asymptotic throughput) for a network is the measure of maximum throughput for a greedy source, for example when the message size (the number of packets per second from a source) approaches infinity.^[6]

Asymptotic bandwidths are usually estimated by sending a number of very large messages through the network, measuring the end-to-end throughput. As other bandwidths, the asymptotic bandwidth is measured in multiples of bits per second.

سعة اتصال الوسائط المتعددة

Digital bandwidth may also refer to: multimedia bit rate or average bitrate after multimedia data compression (source coding), defined as the total amount of data divided by the playback time.

سعة الاتصال في الاستضافة على الوب

In website hosting, the term "bandwidth" is often^{[بحاجة لمصدر]} incorrectly used to describe the amount of data transferred to or from the website or server within a prescribed period of time, for example bandwidth consumption accumulated over a month measured in gigabytes per month. The more accurate phrase used for this meaning of a maximum amount of data transfer each month or given period is monthly data transfer.

سعات وصلات الإنترنت

الجدول التالي يوضح سعة الاتصال القصوى (the physical layer net bitrate, often slightly more than the maximum throughput) of common Internet access technologies. لقائمة أكثر تفصيلا انظر قائمة أجهزة سعة الاتصال.

56 كيلوبت/ث	المودم/ اتصال هاتفي
1.5 ميگابت/ث	ADSL Lite
1.544 ميگابت/ث	T1/DS1
2.048 ميگابت/ث	E1 / E-carrier
10 ميگابت/ث	إيثرنت
11 ميگابت/ث	لاسلكي 802.11b
44.736 ميگابت/ث	T3/DS3
54 ميگابت/ث	لاسلكي 802.11g
100 ميگابت/ث	إيثرنت سريع
155 ميگابت/ث	OC3
600 ميگابت/ث	لاسلكي 802.11n
622 ميگابت/ث	OC12
1 گيگابت/ث	گيگابت إيثرنت
2.5 گيگابت/ث	OC48
9.6 گيگابت/ث	OC192
10 گيگابت/ث	10 گيگابت إيثرنت
100 گيگابت/ث	100 گيگابت إيثرنت

انظر أيضاً

المصادر

^ Andrew S. Tanenbaum Computer networks, Prentice Hall PTR, 2003
^ Douglas Comer, Computer Networks and Internets , page 99 ff, Prentice Hall 2008.
^ Fred Halsall, Introduction to data communications and computer networks, page 108, Addison-Wesley, 1985.
^ Cisco Networking Academy Program: CCNA 1 and 2 companion guide, Volym 1–2, Cisco Academy 2003
^ Behrouz A. Forouzan, Data communications and networking, McGraw-Hill, 2007
^ Modeling Message Passing Overhead by C.Y Chou et al. in Advances in Grid and Pervasive Computing: First International Conference, GPC 2006 edited by Yeh-Ching Chung and José E. Moreira ISBN 3540338098 pages 299-307

[1] Andrew S. Tanenbaum Computer networks, Prentice Hall PTR, 2003

[2] Douglas Comer, Computer Networks and Internets , page 99 ff, Prentice Hall 2008.

[3] Fred Halsall, Introduction to data communications and computer networks, page 108, Addison-Wesley, 1985.

[4] Cisco Networking Academy Program: CCNA 1 and 2 companion guide, Volym 1–2, Cisco Academy 2003

[5] Behrouz A. Forouzan, Data communications and networking, McGraw-Hill, 2007

[6] Modeling Message Passing Overhead by C.Y Chou et al. in Advances in Grid and Pervasive Computing: First International Conference, GPC 2006 edited by Yeh-Ching Chung and José E. Moreira ISBN 3540338098 pages 299-307

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