![]() ![]() The partition information is broadcast in the secondary superframe header. The SA-Preamble sequences are partitioned and each partition is dedicated to a specific base station type, such as macro BS, macro Hot-zone BS, vii femto BS, etc. Structure of PA-preamble compared to the legacy preamble Other problems with the legacy preamble design include the timing accuracy and an insufficient number of preamble sequences for cell planning and deployment (at least 256 distinct sequences are required based on information obtained from early deployments of mobile WiMAX Release 1.0).įIGURE 9-59. The latter would result in poor cell selection/re-selection at the cell edge. This would consume the power of the MS and increase the scanning time. Without this repetition property, the initial frame synchronization algorithms would only rely on the cyclic prefix in every observed OFDM symbol in a radio frame to decide the symbol boundary and to detect the PN sequence with unknown channel impulse response and frequency offset over 114 possible sequences. One of the problems with the legacy preamble design is that when an MS is turned on at a location with a similar distance to three base stations using three different segment preambles, the received preamble would lose its quasi-repetition property because all sub-carriers would be non-zero (except the DC carrier and the guard-band sub-carriers). The legacy preamble sequences carry 114 distinct Cell IDs. The timing and frequency acquisition in the legacy system is a non-hierarchical procedure, i.e., both timing and Cell ID information are acquired in a single step. These sub-carriers are modulated using a boosted BPSK modulation with a specific Pseudo-Noise (PN) code. For each FFT size, three different preamble sub-carrier sets are defined (i.e., frequency reuse-3), differing in the allocation of sub-carriers. In the IEEE 802.16-2009 standard, the preamble is the first OFDM symbol of the frame. The timing and Cell-ID acquisition in IEEE 802.16m is substantially different from that of the legacy system. Structure of the IEEE 802.16m advanced preambles in time and frequency Figure 9-58 shows the structure of the IEEE 802.16m preambles in time and frequency.įIGURE 9-58. The locations of the A-Preamble OFDM symbols are fixed within the superframe. When the new and the legacy systems are co-deployed, the legacy preamble is located at the first OFDM symbol of the legacy frame. The PA-Preamble is located at the first OFDM symbol of the second frame in a superframe, while the SA-Preamble is located at the first OFDM symbol of the first and third frames in the superframe. ![]() One PA-Preamble OFDM symbol and two SA-Preamble OFDM symbols present in every superframe period. The PA-Preamble and SA-Preamble are time-division multiplexed across time. The SA-Preamble is a wideband and cell/sector-specific synchronization signal that is used for fine time/frequency synchronization and cell/sector identification. The PA-Preamble is a narrowband synchronization signal and is common to a group of cells that is used for initial acquisition, superframe synchronization, and broadcast of essential system information. There are two downlink synchronization signals the Primary Advanced Preamble (PA-Preamble) and the Secondary Advanced Preamble (SA-Preamble). ![]() The IEEE 802.16m supports a hierarchical synchronization scheme with two stages. The Advanced Preamble (A-Preamble) or alternatively the synchronization channel is a downlink physical channel which provides a periodic reference signal for system discovery (IEEE 802.16m system beacon), timing and frequency acquisition, frame synchronization, RSSI and path loss measurements, channel estimation, and base station identification. KNOX container, which offers a secure environment in which protected business applications can run with guaranteed information separation from the rest of the device. Security enhancement (SE) for Android, an enforcement mechanism providing protection of system/user data based on confidentiality and integrity requirements through separation. Trust-zone-based integrity measurement architecture (TIMA), which continually monitors kernel integrity. ![]() Trusted boot, that is, preventing unauthorized OS and software from being loaded onto the device at startup. This architecture permits several system-level services, including the following: The key ingredient of this technology is a separation kernel that implements the information isolation. In particular, it permits hot swap between these two content worlds, for example without requiring system restart. This architecture is specifically targeted toward smartphones, and provides secure separation features to enable information partition between business and personal content to coexist on the same system. ![]()
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