Wireless Backhaul – Can You Hear Me Now?
By Dave Pheteplace, Bishop & Associates Inc.

Cell phone and smartphones have become the communications equipment of choice for many people, even to the point that increasing numbers are eschewing their traditional landlines. This is good news for cell phone companies, but the dilemma they face is having sufficient cell phone tower coverage in relation to the caller’s location, the number of callers in a given area, and the volume of data the user is trying to access. As a familiar advertisement asks, “Can you hear me now?”

This backhaul traffic was traditionally handled by the carrier network providers; they leased landlines comprised of T-1/E-1 lines and fiber-optic links to the cell phone providers. The problem is that this infrastructure is not always available where you need it, particularly as more and more cell towers are added to improve the coverage. Here is where microwave backhaul equipment comes in. 

Basic Microwave Backhaul Architecture

Microwave backhaul equipment can bridge the last mile—from the end of the land line to the cell tower—or the last 50 miles. Traditionally, microwave towers, such as the Ericsson MiniLink (right), are what we usually envision for this technology. Line of sight to the next tower is critical to the system operating correctly, so elevation of the antennas is important for these systems. Towers tend to be used for more remote backhaul requirements. In many developing countries, the majority of the infrastructure can be made up of microwave links that are generally less expensive than putting in fiber or copper line systems, particularly in rugged terrain. In city settings, the microwave backhaul systems are often more discretely mounted on buildings and other structures. The older systems tend to be TDM-based (Time Division Multiplexing) for handling multiple analog signals. The newer systems are going digital and operate on IP packet-based transmission of signals.

Most of the newer systems are much more compact than their analog predecessors. The iPasolink system from NEC (left) is a digital microwave system that can operate several network systems at the same time, including 2G, 3G, LTE/4G, and WiMAX. These systems can be designed for indoor or outdoor installation.

The number of I/O connectors on these systems can be substantial. The iPasoLink 200 (pictured above) has shielded RJ45s for 10/100/1000 Base-T, supporting speeds up to Gigabit Ethernet. The antenna connects with an N-type coaxial connector. There are D-sub connectors for control and alarm circuits. The iPasoLink 1000, recently released by NEC, supports both TDM and Ethernet on the same platform, with very high-speed performance. It has more than 60 connectors on the back panel (below), including N-type coaxial connectors for antenna hook up, 10 Gb/s Ethernet SFF, 10/100/1000 Base-T shielded RJ45s, D-subs, SCSI, rectangular power connectors, and LC-type fiber optic connectors for CWDM (Coarse Wavelength Division Multiplexing).

Manufacturers of wireless backhaul equipment include NEC, Ericsson, Huawei, Alcatel-Lucent, Cisco, Juniper, RAD Data, Tellabs, Nokia Siemens, and several others. The market for mobile backhaul is growing, particularly in developing countries. Infonetics Research estimates the market for mobile backhaul equipment to have been $7.2 billion in 2009, and predicts it will grow to $10.4 billion by 2014. Clearly, the connector content in this market will be substantial.

David Pheteplace Bishop & Associates Inc., Managing Director - Cable Assembly Division and Telecom David Pheteplace joined Bishop & Associates Inc. in 2008. As the managing director, he has established a new division for Bishop & Associates focused on the cable assembly industry. Pheteplace is also the market segment director for telecom. He has more than 20 years of experience in the interconnect industry, including managing divisions of Amphenol, Cinch, and Robinson Nugent. Pheteplace can be reached at dpheteplace@bishopinc.com.