Content for TR 38.854 Word version: 17.1.0

5.2.2 Bidirectional SFN p. 12

For the bidirectional scenario RAN4 will consider SFN scenario where there is one panel per RRH with signals to opposite directions along the track (Figure 5.2.2-1).

Copy of original 3GPP image for 3GPP TS 38.854, Fig. 5.2.2-1: SFN scenario with one panel per RRH

Figure 5.2.2-1: SFN scenario with one panel per RRH
(⇒ copy of original 3GPP image)

Additionally, also SFN scenario where there are two panels per RRH (Figure 5.2.2-2).

Copy of original 3GPP image for 3GPP TS 38.854, Fig. 5.2.2-2: SFN scenario with two panels per RRH

Figure 5.2.2-2: SFN scenario with two panels per RRH
(⇒ copy of original 3GPP image)

For the bi-directional scenario the following bi-directional deployment scenario in Table 5.2-2 will be studied:

Table 5.2-2: Assumed deployment parameters for bi-directional scenario.

Parameter	Value
Ds and Dmin	Scenario 2: Ds = 700m and Dmin = 10m Scenario 4: Ds = 700m and Dmin = 150m
RRH height	15m
Number of RRH sites per BBU	4
Number of RRH panels per RRH sites	2 (i.e. bi-directional)
Number of analog beams per RRH panel	1, 2 or 4
RRH panel orientation	Option 1: RRH panel boresight pointed to the railway in the middle point between 2 RRHs. Option 2: RRH panel boresight pointed to the railway at the distance of Ds (projection of the neighboring RRH on the railway). Other options not precluded.
Analog beam orientation	Based on companies' selection for better performance

Candidate schemes for bi-directional deployment for further analysis, scenario 2:

Copy of original 3GPP image for 3GPP TS 38.854, Fig. 5.2.2-3: Connecting to 2nd-Nearest RRH

Figure 5.2.2-3: Connecting to 2nd-Nearest RRH
(⇒ copy of original 3GPP image)

Copy of original 3GPP image for 3GPP TS 38.854, Fig. 5.2.2-4: Scheme-2: Connecting to Nearest RRH except Coverage Hole

Figure 5.2.2-4: Scheme-2: Connecting to Nearest RRH except Coverage Hole
(⇒ copy of original 3GPP image)

For Scenario 2 bi-directional RRH deployment:

[Scheme 1 under bi-directional scenario is feasible without coverage hole issue, and no propagation delay jump between switching points];
Scheme-2 can be used as starting points for further analysis.

Number of beams for bi-directional RRH deployment, Scenario 2:

For scenario 2, bi-directional, RRH parameter: 1 beam per RRH panel, two panels in opposite directions; and
For scenario 2, bi-directional, UE parameter: 1 beam per UE panel (i.e., 2 beams per UE).

Candidate schemes for bi-directional deployment for further analysis, for scenario 4:

Copy of original 3GPP image for 3GPP TS 38.854, Fig. 5.2.2-5: Connecting to 2nd-Nearest RRH

Figure 5.2.2-5: Connecting to 2nd-Nearest RRH
(⇒ copy of original 3GPP image)

Copy of original 3GPP image for 3GPP TS 38.854, Fig. 5.2.2-6: Scheme-2: Connecting to Nearest RRH except Coverage Hole

Figure 5.2.2-6: Scheme-2: Connecting to Nearest RRH except Coverage Hole
(⇒ copy of original 3GPP image)

Copy of original 3GPP image for 3GPP TS 38.854, Fig. 5.2.2-7: Scheme-3: Connecting to Nearest RRH except the area under the RRH

Figure 5.2.2-7: Scheme-3: Connecting to Nearest RRH except the area under the RRH
(⇒ copy of original 3GPP image)

For Scenario 4 bi-directional RRH deployment: the schemes above can be used as starting points for further analysis.

Number of beams for bi-directional RRH deployment, Scenario 4:

For scenario B, bi-directional, RRH parameter:
1. 1 beam per RRH panel; or
2. 2 beams per RRH panel; or
3. 3 beams per RRH panel; or
4. 4 beams per RRH panel.

Note that uneven separation between beams can be considered.

RAN4 agreed that at least 2 beams per RRH panel is considered. Other options are not precluded, and it is FFS whether there are benefits of implementing more beams per RRH panel.

For scenario 4, bi-directional, UE parameter:
1. 1 beam per UE panel; or
2. 2 beams per UE panel; or
3. 7 beams per UE panel.

RAN4 assumes 2 panels to be implemented in the UE side. Only the one active panel per UE can be used for Tx and Rx; and FFS whether another panel can be used for beam search.

RAN4 decided that at least option a) of having 1 beam per panel is considered. Other options are not precluded, and it is FFS whether there are benefits of implementing more beams per UE panel.

For bi-directional RRH deployment, DPS transmission scheme shall be considered.