diff --git a/model_average.py b/model_average.py
index c314bff..aecf1a4 100644
--- a/model_average.py
+++ b/model_average.py
@@ -65,12 +65,12 @@ def train(gpu, args):
     actual_lr          = args.lr * sample_ray_num / 512        # bigger batch -> higher lr (linearity)
     ma_epoch           = args.ma_epoch
     ma_method          = args.ma_method
-    group              = None if not args.group else args.group
     
     train_cnt, ep_start = None, None
 
     rank = args.nr * args.gpus + gpu
-    dist.init_process_group(backend='nccl', init_method='env://', world_size=args.world_size, rank=rank, group_name = group)
+    dist.init_process_group(backend='nccl', init_method='env://', world_size=args.world_size, rank=rank)
+    process_group = dist.new_group(backend = 'nccl')
     torch.cuda.set_device(gpu)
 
     for folder in ("./output/", "./check_points/", "./model/"):
@@ -229,31 +229,31 @@ def run():
             train_sampler.set_epoch(train_cnt)
         if ep % ma_epoch == 0:
             # double barrier to ensure synchronized sending / receiving
-            dist.barrier()
+            dist.barrier(group = process_group)
             comm_timer.tic()
             print(f"Using model average, method: {args.ma_method}... ", end = '')
             if ma_method == 'p2p':
                 # This is a serialized reduce - broadcast (a central node exists)
                 if rank == 0:
-                    param_recv_avg(mip_net, container, model_weights, [1, 2, 3], group = group)
+                    param_recv_avg(mip_net, container, model_weights, [1, 2, 3], group = process_group)
                     # Receive from multiple nodes
-                    param_send(mip_net, dist_ranks = [1, 2, 3], group = group)
+                    param_send(mip_net, dist_ranks = [1, 2, 3], group = process_group)
                 else:
-                    param_send(mip_net, dist_ranks = [0], group = group)
+                    param_send(mip_net, dist_ranks = [0], group = process_group)
                     # Receive from only one node
-                    param_recv(mip_net, source_rank = 0, group = group)
+                    param_recv(mip_net, source_rank = 0, group = process_group)
             elif ma_method == 'broadcast':      # reduce-broadcast (one of the node is the bottleneck)
-                param_reduce(mip_net, model_weights, rank, 0, group = group)
-                param_broadcast(mip_net, 0, group = group)
+                param_reduce(mip_net, model_weights, rank, 0, group = process_group)
+                param_broadcast(mip_net, 0, group = process_group)
             elif ma_method == 'all_reduce':      # all-reduce (one-step reduce-broadcast)
                 for param in mip_net.parameters():
                     param.data *= model_weights[rank]
-                param_all_reduce(mip_net, group = group)
+                param_all_reduce(mip_net, group = process_group)
             else:
                 # TODO: more delicate communication strategy should be implemented
                 # This is basically the case with correlated camera poses
                 pass
-            dist.barrier()
+            dist.barrier(group = process_group)
             comm_timer.toc()
             mean_comm_time = comm_timer.get_mean_time()
             writer.add_scalar('Time/comm time', mean_comm_time, train_cnt)
@@ -312,8 +312,6 @@ def main():
     parser.add_argument('--ma_method', choices=['p2p', 'broadcast', 'delicate', 'all_reduce'], type = str, default = 'p2p',
                         help='Model average strategies')
     
-    parser.add_argument('--group', default="", type=str,
-                        help='Name of the group')
     parser.add_argument('-n', '--nodes', default=1, type=int, metavar='N',
                         help='number of data loading workers (default: 4)')
     parser.add_argument('-g', '--gpus', default=1, type=int,