Cisco Cisco 4G LTE Enhanced High-Speed WAN Interface Cards for LATAM Information Guide
Q&A
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Antenna and Diversity
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Why are there two antenna connectors on the 3G wireless HWIC CDMA module (HWIC-
3G-CDMA), but only one on the 3G HWIC GSM module (HWIC-3G-GSM) for Cisco 1800,
2800, and 3800 Series Integrated Services Routers?
On the 3G HWIC CDMA version, the two antenna connectors provide diversity, allowing for
stronger signal reception in areas where a signal might be poor or otherwise degraded. As a
parallel example, most wireless LAN cards use diversity antennas to offer the PC client the
strongest possible signal. Diversity also allows you to orient one antenna at one angle or
direction and the other at another angle or direction to help improve signal reception.
On the 3G HWIC CDMA version, the two antenna connectors provide diversity, allowing for
stronger signal reception in areas where a signal might be poor or otherwise degraded. As a
parallel example, most wireless LAN cards use diversity antennas to offer the PC client the
strongest possible signal. Diversity also allows you to orient one antenna at one angle or
direction and the other at another angle or direction to help improve signal reception.
The diversity feature is not supported on the 3G HWIC GSM module at this time.
When should I use a diversity antenna?
If the output of the show cellular x/x/x radio command indicates high ECIO values and a low
C/I ratio and you are experiencing poor throughput, you should consider using a diversity
antenna. For example:
If the output of the show cellular x/x/x radio command indicates high ECIO values and a low
C/I ratio and you are experiencing poor throughput, you should consider using a diversity
antenna. For example:
1xRTT related info
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Current RSSI = -52 dBm, ECIO = -7 dBm
Current Channel Number = 507
Current Channel State = Acquired
Current Band Class = Band Class 1
HDR (1xEVDO) related info
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Current RSSI = -51 dBm, ECIO = -6 dBm
Current Channel Number = 325
Current Band Class = Band Class 1
Sector ID (Hex) = 0080:0580:0000:0000:000A:CCF3:0500:A201
Subnet Mask = 104, Color Code = 24, PN Offset = 72
Rx gain control(Main) = -49 dBm, Diversity = -103 dBm
Tx total power = -35 dBm, Tx gain adjust = -1280 dBm
Carrier to interference (C/I) ratio = 3
The C/I ratio should be as high as possible and the ECIO value as low as possible. Lab tests
have indicated ECIO ≤-2 dB. If you observed a value of -7 or something similar, you might
have a very noisy environment, which may in turn cause retransmissions of the packets, lower
throughput, call drops, etc. Cisco does not determine acceptable values; cellular carriers
determine these values. In such a site with such a situation, you need to conduct a survey to
determine how to achieve better signal characteristics.
have indicated ECIO ≤-2 dB. If you observed a value of -7 or something similar, you might
have a very noisy environment, which may in turn cause retransmissions of the packets, lower
throughput, call drops, etc. Cisco does not determine acceptable values; cellular carriers
determine these values. In such a site with such a situation, you need to conduct a survey to
determine how to achieve better signal characteristics.
What advantages does the diversity antenna offer?
Diversity provides relief to a wireless network in a multipath scenario. Diversity antennas are
physically separated from the radio and each other to ensure that one encounters less
multipath propagation effects than the other. Dual antennas typically ensure that if one
antenna is in an RF null then the other is not, providing better performance in multipath
environments.
Diversity provides relief to a wireless network in a multipath scenario. Diversity antennas are
physically separated from the radio and each other to ensure that one encounters less
multipath propagation effects than the other. Dual antennas typically ensure that if one
antenna is in an RF null then the other is not, providing better performance in multipath
environments.
Multipath is a form of RF interference that occurs when a radio signal has more than one path
between the receiver and the transmitter. This situation occurs in cells with metallic or other
between the receiver and the transmitter. This situation occurs in cells with metallic or other