This blog is by Arne Schaelicke, LTE Product Marketing at Nokia Networks.
Hopefully not! And yet I continue to hear about this “box” as one of the propositions for packet scheduling for LTE networks, even though it has been dismissed by 3GPP. This box isn’t a Nokia Networks product, of course, but it’s cause a some irritation as it comes gift-wrapped with the promise of driving up the cell edge performance.
Here’s how the story usually unfolds: “Are your LTE subscribers suffering from degraded data rates at cell edge? No problem. You can overcome this by simply adding an additional network entity, a so-called centralized scheduler, to your radio access network.”
Let’s evaluate this step by step:
Firstly, taking the available spectrum bandwidth and base station grid as given, the cell edge data rate is a question of how effectively interference can be mitigated. This is the task of the scheduler software in the radio network, which needs to identify, avoid and reduce interference. As the transmission time interval in LTE is 1 ms, that’s the speed in which the scheduler needs to act.
Secondly, any sort of information exchange for the coordination of radio cells needs to happen at a similar speed, otherwise there’s a risk that the exchanged data will be outdated before a scheduling decision can be executed. In the vast majority of LTE deployments today, eNodeBs are connected via non-ideal backhaul, which means there is a transport latency of several milliseconds.
Thirdly, inter-eNodeB Coordinated MultiPoint (eCoMP) over non-ideal backhaul has been analyzed by a working group in 3GPP for Release 12 － with contributions by six companies. The research presented by five of them, including Nokia and the other top 3 LTE infrastructure vendors, indicated low gains or even losses for eCoMP compared to the baseline of intra-eNodeB CoMP. The sixth company’s simulation results were considered a clear deviation. As a result, the working group concluded that the research results do not justify the standardization of a new, centralized scheduling network entity in 3GPP Release 12.
In other words: no additional box to be standardized, but instead useful extensions of the existing X2 interface will be evaluated.
So let me ask the provocative question again: Would you really buy an additional and proprietary box that makes your network more complex?
I hope not. But do consider Nokia LTE with the Nokia Smart Scheduler software, which implicitly mitigates interference in uplink and downlink between neighbor eNodeBs. It makes good business sense.
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