Don’t Get Burned with Half-Duplex Capacity Claims
It is finally time to uncover the mystery between FDD and TDD, specifically the importance of FDD as a key element in network performance.
FDD stands for Frequency Division Duplex, and TDD stands for Time Division Duplex. Both FDD and TDD are two spectrum usage techniques, both forms of duplex, used in mobile or fixed wireless broadband links. It is essential to these links that transmission can occur in both directions simultaneously so that data can flow downlink (DL) and uplink (UL) at the same time without any noticeable interruptions.
Recently we’ve kicked off the “Aviat Technology Series” – which are a series of bi-monthly live video streaming webinars for our customers and partners, giving a detailed overview of various technology topics (these are NOT sales pitches…)
Last week, Stuart Little and I gave a live streaming video webinar where we gave an in-depth analysis of all the possible technology options for getting the most out of your microwave system including what’s possible, what’s not, and a realistic look at what you can expect to achieve. We covered the below topics:
• Options for maximizing IP microwave capacity
• Understanding capacity requirements: What’s real and what’s hype
• The timing/availability of new capacity improvement technology
We reviewed techniques for increasing spectrum, improving spectrum utilization and growing effective utilization using higher layer protocol optimizations. Technologies covered included: ling aggregation, co-channel dual polarization (CCDP), adaptive coding and modulation, 512/1024QAM, ethernet header compression, payload compression and asymmetrical RF.
We had lots of great questions and a ton of good feedback. Please email: firstname.lastname@example.org to get the URL for the microwave capacity webinar replay.
Thanks to all who participated and see you in 2 months for the next one when we’ll talk about “Ethernet Protection and Redundancy”
Let’s get past the hype.
We can get a good idea of what capacities 4G networks will need for backhaul we should look at what the technology is actually able to support.
The backhaul requirements for a single cell are fixed by a number of factors, regardless of how many users there are in that cell. Network congestion and frequency interference will limit the throughput achievable to rates well below the advertised peak rates.
For a typical three sector macro cell operating in the maximum 20MHz channel bandwidth, the total backhaul capacity needed is actually below 200 Mbit/s, even with the future introduction of LTE Advanced (Release 10).
For the current Release 8 of LTE now being deployed, and with smaller operating channels of 5 or 10 MHz, the actual backhaul capacity needs will be more often in the 10’s of Mbit/s, not the 100’s!
So if this is the case, why do you need fiber?? It’s pretty clear that the presumption that only fiber is suitable for 4G backhaul doesn’t make much sense! As shown by Figure 1, modern microwave transmission systems more than meet the capacity needs of 4G/LTE, with lots of room to spare.
Microwave supports more than enough backhaul capacity for 4G/LTE
Innovative new microwave technologies have been introduced to the market in the past few years that dramatically increase the throughput capacity, while the move to packet-based transport has also enabled a new range of Ethernet/IP-aware products that are able to intelligently utilize the available microwave backhaul spectrum better than ever before, with throughputs of 1 Gbit/s achievable with fiber-like reliability.
Apart from that, the average cost of microwave has continued to decrease over the years. The result is that microwave $/MBit is a fraction of what it was just 5 years ago.
Why Pay for Capacity That You Don’t Need?
Driven by this continued uncertainty, many operators could waste huge amounts of money by deploying fiber to cell-sites that can be served much more economically with proven microwave solutions.
So far from fiber being the only answer for operators deploying HSPA+ & LTE, microwave transport can and will meet the capacity needs for mobile backhaul for many years to come.
Director of Marketing, Aviat Networks