# Directional Paging for 5G Communications Based on Partitioned User ID
## 3 Proposed PIDP Paging  
In 5G directional communications, due to the limited spatial coverage of each beam, the same paging message is to be transmitted over different beams, resulting in very high paging overhead [25]. In PIDP, we propose to reduce this rising paging overhead in 5G networks by reducing the number of bits included in the paging message being transmitted over different beams. The paging message in every PO is comprised of the UE IDs of all the UE paged in the PO along with RRC overhead bits (e.g., the number of UE IDs and padding), PDCCH bits and Cyclic Redundancy Check (CRC) bits. Network resources required for the broadcast of this paging message further depend on the number of UE and the number of beams. While the number of beams is related to the frequency of operation and the number of UE depends on the user density, the overhead bits are small. Thus, its is inconceivable to reduce beams, overhead bits or user density. Therefore, in this article, we propose to reduce bits for each UE ID included in the paging message, transmitted in every PO, to reduce directional paging overheads. For this, the UE ID is partitioned into two parts as shown in Figure 3. The UE ID is considered to be comprised of \(N\) bits. Instead of \(N\) bits, only '\(N2\)' bits per UE are transmitted in the paging message for all the UE paged in the PO, such that \(N2<N\). The procedures related to the configuration of POs and the distribution of UE over different POs are redesigned in the PIDP mechanism such that the conflicts due to the short UE ID size transmission are avoided. It is thus important to carefully partition the UE ID considering both the bits that would be included in the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Number of Beams** & 16 & 32 & 64 & **LTE** \\ \hline
**System Capacity for Paging (\%)** & 23.6 & 47.2 & 94.4 & **1.47** \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Capacity analysis for directional paging [10]. \begin{table}
\begin{tabular}{c l} \hline \hline
**Work Area** & \multicolumn{2}{c}{**Recent Research Works**} \\ \hline \multirow{4}{*}{Paging and tracking area} & Mobility model for paging area [11] \\  & Rule-based artificial intelligence [13] \\  & Multilevel graph partitioning [14] \\  & Anchor-based location in HetNets [15] \\  & Optimal adjustable extended DRX [16] \\  & Interacted cell concept [17] \\ \hline \multirow{4}{*}{Paging in MTC and IoT} & LTE Group paging for MTC [18] \\  & DRX with quick sleeping [19] \\ \cline{1-1}  & Reacquisition and synchronization [20] \\ \cline{1-1}  & Self-adaptive DRX mechanism [21] \\ \hline \multirow{4}{*}{DRX and 5G} & Tracking area management for 5G [24] \\ \cline{1-1}  & Directional DRX (DDRX) for 5G [23] \\ \cline{1-1}  & Hybrid-DDRX [22] \\ \cline{1-1}  & Mobile-assisted directional paging [25] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Recent related work. paging message and also the bits that would be used to configure the PO. Three major steps of the proposed PIDP mechanism, (i) partitioning, (ii) configuring and (iii) distribution, can be elaborated as:  
1. Partitioning : The first step of the PIDP mechanism involves partitioning of Nbits of the UE ID into two parts. UE ID Part 1 is comprised of the \(N1\) least significant bits of the UE ID. UE ID Part 2 is made up of the \(N2\) most significant bits of the UE ID. \(N1\) and \(N2\) together provide the complete information of the UE ID as shown in Figure 3. \[N=N1+N2\] (5) We propose that only UE ID Part 2 (comprised of \(N2\) bits) is transmitted in the paging message instead of the entire N bits. Since several UE are configured in each PO and there are multiple POs per IDRX cycle, the reduction in bits to be transmitted per UE would result in the saving of network resources. Moreover, the savings is expected to be substantial as the same paging message is transmitted over several beams. 2. Configuring: It is not always possible to page all UE in the same PO, and it depends on factors like paging load, tracking area size and user density.