As I mention before in my older articel-为何不能在TDS里用跳频技术？Pls refer to this: http://www.cnttr.com/34443/viewspace_118144.html

Today when I reading some books about frquecny hopping, and I still feel maybe FH is a method to improve system performance in TDS system. Of course, we could do this by RRM algorithm not pure physical layer procedure.

As we know, FH(Frequency hopping) have two methods: BB hoping(or Synthsizer FH) and RF Hopping. And if Basestation could be physically configured with huge TRXs, thus, similar performance will be achived comparing with RF hopping. But in real delpoyment, maximum 8 or 12 TRXs is. Thus, normally RF hopping is used in real case.

For TDS system, due to more width of carrier is compared with GSM: 1.6M vs 200k. Thus, less number of carrier is for certain band. (current,2010-2025Mhz is defined for china TDS trial system). So, cleary RF hopping is not suitable for.

But we also know, the gain could be gotten for FH with slow moving environement to avoid long time fading.

In TDS system, due to 1.6MHz bandwith of carrier, and this value is not large or small comparing with coherent bandwidth in some case.(for this,WCDMA 5MHz have could present more characteristic on frequency non-selected channel). Thus, in some case, TDS channel is a frequency selected channel. Thus, the appropriate gain could be gotted by new used frequency.

(1)If FH action is don by mobile automatically, this is a pure physical procedure with better performance.

(2)But we could do similar action as FH by higher layer signalling-RRC layer. For example, if RNC find the large errors on UL packets, then RRM in RNC could assign new frequency point with second or third TRX by some RRC procedures, such as, "Physical Channel Reconfig Request" to change used frequency. This method is similar with BB hopping.

The difference for method 1 and 2 is time. The more quicker action is for method 1 than method 2. Although method 2 need to do by RRC procedure. And the delay time is based on 100ms. This action need cost about several hundred ms. Thus,the key point is time. If performance could be insisted on this, thus, maybe this method-2 could be trial.(we need verify).

Sharing with you

James