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Self-organizing networks (SON) are a key element of next-generation radio access networks, especially LTE where SON techniques are an integral part of the LTE specifications. While SON in the RAN network has been defined through organizations like 3GPP and NGMN, SON in the mobile backhaul space remains undefined. I’d like to present my take on what SON means in the context of small cell mobile backhaul, where SON techniques are set to play a prominent role.
SON techniques in mobile backhaul, as they are in the RAN, are fundamentally aimed at reducing total cost of ownership and enabling scalability of deployment. This is particularly important when it comes to non-line-of-sight small cell backhaul. Low-cost backhaul is a necessity if the small cell market is to take off. SON in NLOS mobile backhaul is a key element in realizing the business case. So, what are the elements of SON in small cell NLOS mobile backhaul?
There are, in my opinion, at least two key elements that I will address in this post: self-configuration and self-optimization. Self-configuration automates the process of configuring and integrating new backhaul nodes in the backhaul network. It serves to shorten the deployment process and increase the reliability of the configuration process by eliminating errors due to manual entry or other user-induced errors.
Self-optimization is primarily geared toward interference management, the target of which is to reduce co-channel interference. Doing this increases link capacity and reliability. It also serves to reduce the backhaul spectrum requirements by enabling tighter frequency reuse plan in the backhaul network.
Whereas self-configuration happens at the time of deployment and installation, self-optimization can be an ongoing process that starts at the product deployment cycle (i.e., determining the best hub for a remote backhaul module – a process called clustering) and continues by “monitoring” the wireless channel quality of every link in the backhaul network. Data collected during the monitoring process is then used to manage the transmitted power as well as to implement techniques such as coordinated scheduling to reduce co-channel interference.
Implementing backhaul SON (B-SON) algorithms is a fundamental part of enabling the small cell business case. By simplifying and automating the deployment process, greater scalability can be achieved. Higher efficiency is derived from self-optimization techniques that maximize spectrum utilization. Ease of use and deployment is a key differentiator in the small cell backhaul space, and B-SON is a critical feature in achieving this objective.
Just wondering what spectrum and bandwidth would be used for B-SON for LTE? I can visualize every third utility pole would be connected to fiber (probably multi radio mesh with single hop). Backhaul SON definitely an excellent concept, just the backhaul spectrum is the issue.
Spectrum depends on the country and region. For example, 3.x GHz is available and very inexpensive (<1 cent/MHz-PoP). Recently, 2.57-2.62 GHz is made available through auctions in Europe also at low prices (2-3 e-cent/MHz-PoP).
Good article Frank.
Few questions.
1. What kind of frequency reuse would be possible using the NLOS solution for backhaul
2. With the added cost of interference management, will the price point of NLOS backhaul solution in the 2.x or 3.x Ghz be competetive to that of Carrier WiFi or Wimax/LTE-TDD based backhaul sysytems
3. Is it going to be a single box solution for both 2.x & 3.x freq bands (SW configurable) or separate HW boxes ?
-Teer
Frequency reuse can be N=1 or greater if more spectrum is available.
On the pricing and comparison to WiFi and WiMAX/LTE, I don’t see WiFi being a major solution to small cell backhaul because of interference which reduces reliability/capacity. One may say to use 5 GHz UNII bands, but they will get more congested as more devices become available in these bands (especially 5.8 GHz). WiMAX/TD-LTE is not a solution too because they are access technologies with typically high latency (FDD LTE latency reported in the media is anywhere between 20-45 msec). NLOS backhaul can also provide higher capacity than either of these two technologies.
Finally, I see different boxes for different bands.
Sounds like mesh networking to me. Actually todays mesh has more features – content aware, multi-level QoS, Service Groups, dynamic self-optimization, self healing, spectrum agile, etc., etc.