Clusterhead Synchronization Channel (P-CHSCH,S-CHSCH) Signaling Format
[Framing and Channel Multiplexing]

The main purposes of this channel are

  1. Timing (TTI/symbol) synchronization for nodes inside the cluster
  2. Frequency sychronization for nodes inside the cluster
  3. Timing (TTI/symbol) sychronization for clusterheads in adjacent clusters
  4. Frequency synchronization for clusterheads in adjacent clusters

It is emitted once per TTI in conjunction with the clusterhead broadcast channel (P-CHBCH,S-CHSCH). Aside from its primary purposes above, it is also intended to be exploited for channel estimation prior to demodulation of the CHBCH, since the CHBCH does not comprise pilot signals and the clusterhead does not use the MCH. The number of symbols required, $N_{\mathrm{s,CHSCH}}$, depend on the desired time and frequency acquisition precision.

The x-CHSCH is a pseudo-random QPSK sequence defined in the frequency domain by the bit sequences $\mathrm{Re}\{\mathbf{c}_i\}, \mathrm{Im}\{\mathbf{c}_i\}, i=0,1,\cdots,\lfloor(N_{\mathrm{d}} - N_{\mathrm{z}})N_{\mathrm{s,CHSCH}}/32 \rfloor -1$. If multiple transmit antennas (up to $N_d/N_c$) are used on the same frequency carrier, the CHSCH sequence, $\mathbf{c}_{\mathrm{CHSCH,2}}$, shall be cyclicly shifted by $iN_\mathrm{c}, i=1,2,\cdots,N_\mathrm{ant}$ samples on antenna $i$ prior to cyclic extension. This is to allow nodes to estimate the different channels of the clusterhead efficiently in the frequency domain.

The transmit power of the CHSCH shall be adjustable by higher layers in order to control the detection range of the clusterhead.

The parameters of the CHSCH are summarized in the following table and represented by the primitive PHY_CHSCH

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