Table 4 Comparison system latency
From: Orthogonal beamforming using Gram-Schmidt orthogonalization for multi-user MIMO downlink system
| Â | LF-OSDMA | Extended LF-OSDMA | Proposed method |
|---|---|---|---|
BS → User (Step 1 or Step I) | δ BC | δ BC | δ BC |
User → BS (Step 2 or Step II) | δ all | δ all | δ select |
BS → User (Step 4 or Step IV) |  | δ ad | δ ad |
User → BS (Step 5 or Step V) |  | δ all | δ all |