FWA Design & Planning

MW (wireless) backhaul, also known as “wireless backhaul transport”, is a means for connecting broadband sites to the core network in a wireless manner. In the case of mobile networks, this is a common way to connect a radio access network (RAN) (e.g. a base station, eNodeB/eNB or gNodeB/gNB) to the core of the mobile network – without the need to deploy optical fiber. It is mostly and mainly used when high-speed wireline connectivity to telecom sites (typically via fiber optics) is unavailable, when rapid deployment is required, and when a cost-efficient solution is needed.

According to standards there are expected to be two main deployment options: Short-haul solution, which typically provide wireless link capacity of up to 20 Gbps, are used in the access and aggregation backhaul segments over short distances ranging between several hundred feet to 10 miles. Short-haul links deployed in access applications (macrocells and small cells) wirelessly connect individual base stations and cellular towers to the core network. Long-haul solutions which also provide multi-Gbps capacity, are used in the main backbone of the telecommunication network. These links are used to carry services at distances of 10 to 100 miles, and, using the right planning, configuration and equipment, can also bridge distances of over 150 miles.

There are typically two major band groups for MW backhaul design. The 4-11 GHz band range where these frequencies are typically used for long-haul connectivity (typically above 7 km distances). While these frequencies excel in propagation, they typically bear higher fees and channel width availability is rather low (from 28/30 MHz to 56/60 MHz and, in rare cases, 112 MHz) leading to lower rates. It is important from PoC point of view to test the link availability and optional features configured to improve performance and capacity. The other band range is the 6-42 GHz where these frequencies are typically used for short-haul connectivity (typically 2-7 km distances). The higher bands within the range often make wider channels available – 112 MHz and even 224 MHz but the major disadvantage to test in PoC is the SINR and the overall throughput against pathloss and radio propagation discrepancies.

The network performance of radio system could be evaluated in different aspects, and mobile network operators (MNOs) are unusually most interested in the indicators like peak throughput, cell capacity, spectrum efficiency and latency. Those indicators will have different influences based on the nature of application, and end users’ mobile broadband experiences could be quantized in those counters. Most typically peak throughput measures the maximum data rate that an end use could possibly get, which set the up boundary of application consumption. When it comes to the testing of user peak throughput, file downloading and uploading based on TCP and UDP have usually been selected as a typical application. Typical factors and parameter configurations to be revised are TDD frame, bandwidth, multi antenna MIMO and mMIMO modes, modulation type and error correction coding. Finally regarding spectral efficiency and according to ITU-R, requirements for the peak spectral efficiency are 15 bps/Hz and 6.75 bps/Hz for downlink and uplink respectively, and those targets have been fulfilled by LTE-TDD (TD-LTE).