كفاءة عرض المحزم

كفاءة عرض المحزم في تكنولوجيا الاتصالات بالانجليزية bandwidth efficiency أوSpectral efficiency هي النسبة بين معدل إرسال المعلومات [بايت/ثانية) وعرض محزم الإشارة بالهرتز . وهي خاصية هامة في ي إطار طرق تعديل الإشارات signal modulation.

مثال

إذا كان لدينا وسيلة للبث ذوعرض محزم قدره 1 كيلوهرتز (1000 هرتز) وأجرينا الارسال بمعدل 1000 بايت /ثانية تكون وسيلة الارسال ذات كفاءة عرض محزم أوكفاءة تعديل إشارة مقدارها 1 بايت/هرتز.

إذا كانت النسبة بين الإشارة والشوشرة عالية امكن حمل كفاءة عرض المحزم ارتفاعا كبيرا ، فمثلا إذا كان مودم يعمل على خط تلفوني بعرض محزم قدره 3500 هرتز أمكن إرسال المعلومات بمعدل 33600 بايت/ثانية . وتكون كفاءة عرض المحزم في هذه الحالة : (33600 بايت في الثانية) / 3500 هرتز ≈ 10; ${\displaystyle \mathrm {\tfrac {Bit {s\cdot Hz$ .

جدول مقارنة

Examples of predicted numerical spectral efficiency values of some common communication systems can be found in the table below. These results will not be achieved in all systems. Those further from the transmitter will not get this performance.

كفاءة عرض الحزمة لأنظمة الاتصالات الشائعة

الخدمة	المعيار	أُطلِقت، سنة	Max. net bitrate per carrier and spatial stream, R (Mbit/s)	Bandwidth per carrier, B (MHz)	Max. link spectral efficiency, R/B (bit/s⋅Hz)		Typical reuse factor, 1/K	System spectral efficiency, R/B⋅K (bit/s⋅Hz per site)
الخدمة	المعيار	أُطلِقت، سنة	Max. net bitrate per carrier and spatial stream, R (Mbit/s)	Bandwidth per carrier, B (MHz)	SISO	MIMO	Typical reuse factor, 1/K	System spectral efficiency, R/B⋅K (bit/s⋅Hz per site)
1G cellular	NMT 450 modem	1981	0.0012	0.025	0.45	N/A	0.142857 ¹⁄₇	0.064
1G cellular	AMPS modem	1983	0.0003	0.030	0.001	N/A	0.142857 ¹⁄₇	0.0015
2G cellular	GSM	1991	0.104 0.013 ×ثمانية timeslots = 0.104	0.200 0.2	0.52	N/A	0.1111111 ¹⁄₉ (¹⁄₃ in 1999)	0.17000 0.17 (in 1999)
2G cellular	D-AMPS	1991	0.039 0.013 × ثلاثة timeslots = 0.039	0.030	1.3	N/A	0.1111111 ¹⁄₉ (¹⁄₃ in 1999)	0.45 0.45 (in 1999)
2.75G cellular	CDMA2000 1× voice	2000	0.0096 0.0096 per phone call × 22 calls	1.2288	0.0078 per call	N/A	1	0.172 (fully loaded)
2.75G cellular	GSM + EDGE	2003	0.384 (typ. 0.20)	0.2	1.92 (typ. 1.00)	N/A	0.33333 ¹⁄₃	0.33
2.75G cellular	IS-136HS + EDGE		0.384 (typ. 0.27)	0.200	1.92 (typ. 1.35)	N/A	0.33333 ¹⁄₃	0.45
3G cellular	WCDMA FDD	2001	0.384	5	0.077	N/A	1	0.51
3G cellular	CDMA2000 1× PD	2002	0.153	1.2288	0.125	N/A	1	0.1720 (fully loaded)
3G cellular	CDMA2000 1×EV-DO Rev.A	2002	3.072	1.2288	2.5	N/A	1	1.3
Fixed WiMAX	IEEE 802.16d	2004	96	20	4.8		0.25 ¹⁄₄	1.2
3.5G cellular	HSDPA	2007	21.1	5	4.22		1	4.22
4G MBWA	iBurst HC-SDMA	2005	3.9	0.625		7.3	1	7.3
4G cellular	LTE	2009	81.6	20	4.08	16.32 (4×4)	1 (0.33333 ¹⁄₃ at the perimeters)	16.32
4G cellular	LTE-Advanced	2013	75	20	3.75	30.00 (8×8)	1 (0.33333 ¹⁄₃ at the perimeters)	30
واي فاي	IEEE 802.11a/g	2003	54	20	2.7	N/A	0.33333 ¹⁄₃^[]	0.900
واي فاي	IEEE 802.11n	2007	72.2 (up to 150)	20 (up to 40)	3.61 (up to 3.75)	Up to 15.0 (4×4, 40 MHz)	0.33333 ¹⁄₃^[]	5.0 (4×4, 40 MHz)
Wi-Fi	IEEE 802.11ac	2012	433.3 (up to 866.7)	80 (up to 160)	5.42	Up to 43.3 (8×8, 160 MHz)	0.33333 ¹⁄₃^[]	14.4 (8×8, 160 MHz)
WiGig	IEEE 802.11ad	2013	6756	2160	3	N/A	1^[]	3
Trunked radio system	TETRA, low FEC	1998	0.019 4 timeslots = 0.019 (0.029 without FEC)	0.025	0.8	N/A	0.142857 ¹⁄₇	0.1
Trunked radio system	TETRA II with TEDS, 64-QAM, 150kHz, low FEC	2011	0.538 4 timeslots = 0.538	0.150 (scalable to 0.025)	3.6	N/A
Digital radio	DAB	1995	0.576 to 1.152	1.712	0.34 to 0.67	N/A	0.200 ¹⁄₅	0.07 to 0.13
Digital radio	DAB with SFN	1995	0.576 to 1.152	1.712	0.34 to 0.67	N/A	1	0.34 to 0.67
Digital TV	DVB-T	1997	31.67 (typ. 24)	8	4.0 (typ. 3.0)	N/A	0.143 ¹⁄₇	0.57
Digital TV	DVB-T with SFN	1996	31.67 (typ. 24)	8	4.0 (typ. 3.0)	N/A	1	4.0 (typ. 3.0)
Digital TV	DVB-T2	2009	45.5 (typ. 40)	8	5.7 (typ. 5.0)	N/A	0.143 ¹⁄₇	0.81
Digital TV	DVB-T2 with SFN	2009	45.5 (typ. 40)	8	5.7 (typ. 5.0)	N/A	1	5.7 (typ. 5.0)
Digital TV	DVB-S	1995	33.8 for 5.1 C/N (44.4 for 7.8 C/N)	27.5	1.2 (1.6)	N/A	0.250 ¹⁄₄	0.3 (0.4)
Digital TV	DVB-S2	2005	46 for 5.1 C/N (58.8 for 7.8 C/N)	typ. 30	1.5 (2.0)	N/A	0.250 ¹⁄₄	0.4 (0.5)
Digital TV	ATSC with DTx	1996	32	19.39	1.6	N/A	1	3.23
Digital TV	DVB-H	2007	5.5 to 11	8	0.68 to 1.4	N/A	0.200 ¹⁄₅	0.14 to 0.28
Digital TV	DVB-H with SFN	2007	5.5 to 11	8	0.68 to 1.4	N/A	1	0.68 to 1.4
Digital cable TV	DVB-C 256-QAM mode	1994	38	6	6.33	N/A	N/A	N/A
Broadband CATV modem	DOCSIS 3.1 QAM-4096, 25kHz OFDM spacing, LDPC	2016	1890	192	9.84	N/A	N/A	N/A
Broadband modem	ADSL2 downlink		12	0.962	12.47	N/A	N/A	N/A
Broadband modem	ADSL2+ downlink		28	2.109	13.59	N/A	N/A	N/A
Telephone modem	V.92 downlink	1999	0.056	0.004	14.0	N/A	N/A	N/A

N/A means not applicable.

انظر أيضاً

Baud
CDMA spectral efficiency
Channel capacity
Comparison of mobile phone standards
Cooper's Law
Goodput
Radio resource management (RRM)
Spatial capacity
Throughput
Orders of magnitude (bit rate)

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