diff --git a/pcdet/models/model_utils/transfusion_utils.py b/pcdet/models/model_utils/transfusion_utils.py
new file mode 100644
index 0000000..677827c
--- /dev/null
+++ b/pcdet/models/model_utils/transfusion_utils.py
@@ -0,0 +1,102 @@
+import torch
+from torch import nn
+import torch.nn.functional as F
+
+def clip_sigmoid(x, eps=1e-4):
+    y = torch.clamp(x.sigmoid_(), min=eps, max=1 - eps)
+    return y
+
+
+class PositionEmbeddingLearned(nn.Module):
+    """
+    Absolute pos embedding, learned.
+    """
+
+    def __init__(self, input_channel, num_pos_feats=288):
+        super().__init__()
+        self.position_embedding_head = nn.Sequential(
+            nn.Conv1d(input_channel, num_pos_feats, kernel_size=1),
+            nn.BatchNorm1d(num_pos_feats),
+            nn.ReLU(inplace=True),
+            nn.Conv1d(num_pos_feats, num_pos_feats, kernel_size=1))
+
+    def forward(self, xyz):
+        xyz = xyz.transpose(1, 2).contiguous()
+        position_embedding = self.position_embedding_head(xyz)
+        return position_embedding
+
+
+class TransformerDecoderLayer(nn.Module):
+    def __init__(self, d_model, nhead, dim_feedforward=2048, dropout=0.1, activation="relu",
+                 self_posembed=None, cross_posembed=None, cross_only=False):
+        super().__init__()
+        self.cross_only = cross_only
+        if not self.cross_only:
+            self.self_attn = nn.MultiheadAttention(d_model, nhead, dropout=dropout)
+        self.multihead_attn = nn.MultiheadAttention(d_model, nhead, dropout=dropout)
+        # Implementation of Feedforward model
+        self.linear1 = nn.Linear(d_model, dim_feedforward)
+        self.dropout = nn.Dropout(dropout)
+        self.linear2 = nn.Linear(dim_feedforward, d_model)
+
+        self.norm1 = nn.LayerNorm(d_model)
+        self.norm2 = nn.LayerNorm(d_model)
+        self.norm3 = nn.LayerNorm(d_model)
+        self.dropout1 = nn.Dropout(dropout)
+        self.dropout2 = nn.Dropout(dropout)
+        self.dropout3 = nn.Dropout(dropout)
+
+        def _get_activation_fn(activation):
+            """Return an activation function given a string"""
+            if activation == "relu":
+                return F.relu
+            if activation == "gelu":
+                return F.gelu
+            if activation == "glu":
+                return F.glu
+            raise RuntimeError(F"activation should be relu/gelu, not {activation}.")
+
+        self.activation = _get_activation_fn(activation)
+
+        self.self_posembed = self_posembed
+        self.cross_posembed = cross_posembed
+
+    def with_pos_embed(self, tensor, pos_embed):
+        return tensor if pos_embed is None else tensor + pos_embed
+
+    def forward(self, query, key, query_pos, key_pos, key_padding_mask=None, attn_mask=None):
+        # NxCxP to PxNxC
+        if self.self_posembed is not None:
+            query_pos_embed = self.self_posembed(query_pos).permute(2, 0, 1)
+        else:
+            query_pos_embed = None
+        if self.cross_posembed is not None:
+            key_pos_embed = self.cross_posembed(key_pos).permute(2, 0, 1)
+        else:
+            key_pos_embed = None
+
+        query = query.permute(2, 0, 1)
+        key = key.permute(2, 0, 1)
+
+        if not self.cross_only:
+            q = k = v = self.with_pos_embed(query, query_pos_embed)
+            query2 = self.self_attn(q, k, value=v)[0]
+            query = query + self.dropout1(query2)
+            query = self.norm1(query)
+        
+        query2 = self.multihead_attn(query=self.with_pos_embed(query, query_pos_embed),
+                                     key=self.with_pos_embed(key, key_pos_embed),
+                                     value=self.with_pos_embed(key, key_pos_embed), 
+                                     key_padding_mask=key_padding_mask, attn_mask=attn_mask)[0]
+
+        query = query + self.dropout2(query2)
+        query = self.norm2(query)
+
+        query2 = self.linear2(self.dropout(self.activation(self.linear1(query))))
+        query = query + self.dropout3(query2)
+        query = self.norm3(query)
+
+        # NxCxP to PxNxC
+        query = query.permute(1, 2, 0)
+        return query
+