Microwave links provide the bulk of the interconnectivity between sites in telecommunications networks (especially mobile voice and data networks) because they are rapidly deployable, relatively small and require less infrastructure outlay than technologies such as fibre transmission.

Microwave links have been proven cost-effective in network deployments where traffic requires are medium to high capacity between sites. They are the most practical solution to provide service quickly with availability in excess of 99.99%.

Microwave links can provide a variety of interfaces to suit modern requirements. These include in some cases mixed internet protocol (IP) and traditional STM1/E1 or alternatively more traditional interfaces using one or other technology.

Typical Applications

• Mobile backhaul links - between 2G/3G base stations
• WiMAX/LTE backhaul links
• Inter-site links for military, corporate and private networks
• Fixed network links to provide connectivity and bandwidth where fibre transmission is too costly or unreliable
• Temporary links for anticipated demand or growth areas in any of the above applications

Protection

To further improve the link availability in situations of extreme path conditions or applications demanding high reliability, it is possible to configure the microwave link to have redundancy or protection. This can be configured as hot-standby, full redundancy and space diversity depending on the solution and application.

Frequency Considerations

Microwave links are available in both licensed and unlicensed frequency bands from 2.4 GHz to 86 GHz. Depending on the application distance, required link capacity, geographic considerations and spectral requirements, each band is suited to particular distances and traffic types.

The table below shows frequency band available for microwave links. The unlicensed frequency bands tend to be used where the networks provide best-effort type of service at low cost such as Internet Service Providers (ISPs). Licensed bands are used in preference where the operator requires guaranteed performance (minimal interference problems from other users). In some special cases, the bands are allocated to particular user classes such as the 4.5 GHz band for military use.

For example, the table below shows typical distances, link capacities and traffic types per frequency band:

Freq Band (GHz)	Licensed Band	Traffic Types	Capacity (Mbit/s) Note 1	Typical Link Distances (km) Note 2	Products
2.4 / 5.4 / 5.8	N	Ethernet FE/GE, STM1 & nxE1	10 to 155	Up to 30	StarGate StarLink
4.5	Y	Ethernet FE/GE & nxE1	10 to 80	Up to 100	HDR5
6 / 7 / 8	Y	Ethernet FE/GE, STM1 & nxE1	10 to 400 (800 with 2+0)	Up to 70	IP-10 StarLink
11 / 13	Y	Ethernet FE/GE, STM1 & nxE1	10 to 400 (800 with 2+0)	Up to 40	IP-10 StarLink
15	Y	Ethernet FE/GE, STM1 & nxE1	10 to 400 (800 with 2+0)	Up to 30	IP-10 StarLink
18 / 23	Y	Ethernet FE/GE, STM1 & nxE1	10 to 400 (800 with 2+0)	Up to 15	IP-10 StarLink
26	Y	Ethernet FE/GE, STM1 & nxE1	10 to 400 (800 with 2+0)	Up to 10	IP-10 StarLink
38	Y	Ethernet FE/GE, STM1 & nxE1	10 to 400 (800 with 2+0)	Up to 5	IP-10
71 to 86	Y	Gigabit Ethernet	1,250/2,500 (1.25/2.5 Gb/s)	Up to 5	E-Band

The values above are indicative, specifications subject to change without notice.

Note 1: Capacity shown is nominal throughput for varying packet sizes between 64 bytes and 1522 bytes.

Note 2: Distance dependant on Rainfall Region and antenna size

Advantages and Disadvantages

For microwave and millimeter wave link applications, there are several advantages and disadvantages as summarized below.

Microwave (2 to 38 GHz)

• Summary
• 10 to 800 Mbps or 1 to 10 x STM1 (N+1)
• Beyond 50 km (clear line of sight required)
• Distance is dependant on link capacity
• All links offer SNMP based element management and integration into network management system
• Advantages
• Guaranteed interference & regulatory protection
• Installation time - number of days (usually 1 to 5 days)
• Cost of ownership - medium to high (capacity dependant)
• Long distances possible with multiple hops (beyond 1000 km)
• Robust - protected mode in a licensed band
• Disadvantages
• Finite licensed band spectrum - requires spectrum management & RF Planning
• Requires line of sight between end points
• Requires antenna mounting/mast at each site

Millimeter Wave (71 to 86 GHz band)

• Summary
• Up to 2.5 Gbps (10 Gbps possible in the future)
• Up to 5 km
• All links offer SNMP based element management and integration into network management system
• Advantages
• Not heavily regulated - 'light licensing'
• Installation time - hours/days
• Cost of ownership - medium to high
• Robust - protected mode
• Disadvantages
• Limited distance
• Annual license fees for spectrum

Conclusion

Tellumat has a broad set of microwave link alternatives depending on your requirements. Please complete an online enquiry form for us to assist with the design and implementation of your wireless network.