The adoption of wireless communication in various fields has created the needs for easy wireless network construction and optimal wireless system selection, considering the coexistence of multiple wireless systems. In this paper, we propose two main contributions: a database that describes indoor building information and a wireless estimation method that uses deep learning. The first contribution involves digitizing indoor building information and creating the database for the building information, while the second utilizes the database to operate a deep learning model called RadioResUNet, which predicts the radio signal strength (RSS) of a 2.4 GHz Wi-Fi system in complex indoor environments with multiple walls and obstacles. By leveraging the building information database, the deep learning-based radio estimation method enables the estimation of RSS for a given building configuration and the position of the access point (AP). This method also allows for radio prediction in a desired area in advance, even when updating the indoor building information in the database. It can save time and expense while ensuring ongoing wireless connectivity support by comprehending the wireless situation of the new indoor building configuration,

The authors present dynamic reencryption of return addresses to mitigate their leakage. The authors’ method enforces programs to save return addresses as encrypted and renew the encryption states with fresh keys before or after vulnerable operations. When a function returns, it should restore the return address from its encryption using the most recent key not to cause a crash. Under the protection of their method, return addresses and keys may leak, but the disclosed bits become garbage because keys govern all return addresses through encryption, while changing before control‐flow proceeds into a vulnerable region. As a result, it becomes probabilistically infeasible to build exploits for intercepting control‐flow by using leaked return addresses or keys. They implemented the proposed method as an extension of the LLVM compiler that inserts reencryption code where necessary. They also have confirmed its effectiveness against information leak attacks carried out in the early stage of blind return‐oriented programming (BROP). The performance overhead ranges below 11.6% for processor‐intensive programs and 4.12% or less for web servers.

This paper proposes geographical group MAC (G-MAC) for event-driven wireless sensor networks. G-MAC is a hybrid MAC protocol combined with the contention-based and contention-free MAC protocols. Collision avoidance is one major task in the contention-based MAC protocols. Collision is much significant as a channel is shared by a large number of contending hosts. If it is possible to reduce the number of contending hosts, collisions could be decreased. This is a basic idea of the proposed G-MAC. By diving the area covered by the sensing hosts into the multiple geographical groups and by separating the channel access time for each group, it could reduce the number of contending hosts. Also, G-MAC needs the time synchronization and channel access scheduling for the separating groups to avoid the interference with others. Simply to say, the proposed G-MAC works on the contention-based channel access for the hosts within a group, but operates on the contention-free channel access among the groups. Computer simulation is conducted to study the effects of the number of groups on collision, packet loss and delay. This paper presents that the proposed G-MAC has the superior performance of collision avoidance and packet loss compared to the contention-based MAC protocols.

This paper proposes a space-time scheduling algorithm that improves the throughput performance of millimeter-wave wireless personal/local area network(mmWave WPAN/WLAN) systems. The upcoming mmWave WPAN/WLAN systems are designed to support high definition TV (HDTV) transmission, high speed wireless docking and gaming, etc. These data-rate-greedy applications require Gbits/s or even multi-Gbits/s transmission capacity which can be provided by the mmWave bands. Directional antenna are preferred in these bands to compensate high path loss. However the narrowed transmission angle of directional antenna makes the system susceptible to blockage of human body or furniture. Consequently, the throughput performance is compromised and may not meet the requirement of the targeting applications. Cooperative relay with time slot sharing is a solution to guarantee throughput under such situation. Compared with lower frequency bands, it is easier in mmWave bands to share time slot between the direct path and relay path, due to less co-channel interference constrained by path loss. In this paper, we propose a space-time scheduling algorithm to assist cooperative relay. The algorithm is based on graph theory and designed to find optimized relay station and time slot to maximize the system throughput. Computer simulations demonstrate over 25 percent throughput improvement is achieved under conference room None-line-of-sight (NLOS) environment with human blockage. The achieved performance meets the requirement of uncompressed HDTV transmission.

In this paper, we proposes the pro-active beamforming (BF) protocol realized in media access control (MAC) layer following IEEE 802.15.3c criteria for millimeter-wave 60GHz wireless personal area networks (60GHz WPANs). The pro-active BF may be used when the piconet controller (PNC) is the source of data to one or multiple devices (DEVs). It allows multiple DEVs to train their own receiver antennas for optimal reception from the PNC with lower overhead. The pro-active BF realizes part of BF operation in association process, extending the system's BF capability. It also enables DEVs to associate with PNC with directional antenna pattern, thus enlarges the coverage area of a piconet. Since it may train multiple users simultaneously based on the proposed multi-resolution codebooks, it significantly decreases the BF set-up time and mitigates the high path loss of 60GHz WPAN systems. Simulation results show that the proposed pro-active BF further reduce more than 20% of the BF set-up time comparing with on-demand BF in the multiple DEVs scenarios. It is completely compliant to IEEE 802.15.3c, and adopted by IEEE 802.15.3c as an important compliment to the on-demand BF to realize Giga-bit-per-second (Gbps) communication in WPAN Systems.

In this paper, we propose a feasible beamforming (BF) scheme realized in media access control (MAC) layer following the guidelines of the IEEE 802.15.3c criteria for millimeterwave 60 GHz wireless personal area networks (60 GHz WPANs). The proposed BF targets to minimize the BF set-up time and mitigates the high path loss of 60 GHz WPAN systems. It is based on designed multi-resolution codebooks, which generate three kinds of patterns of different half power beam widths (HPBWs): quasi-omni pattern, sector and beam. These three kinds of patterns are employed in the three stages of the BF protocol, namely device-to-device (DEV-to-DEV) linking, sector-level searching and beam-level searching. All the three stages can be completed within one superframe, which minimizes the potential interference to other systems during BF set-up period. In this paper, we show some example codebooks and provide the details of BF procedure. Simulation results show that the setup time of the proposed BF protocol is as small as 2% when compared to the exhaustive searching protocol. The proposed BF is a complete design, it re-uses commands specified in IEEE 802.15.3c, completely compliant to the standard; It has thus been adopted by IEEE 802.15.3c as an optional functionality to realize Giga-bit-per-second (Gbps) communication in WPAN Systems.

This paper studies the throughput of IEEE mmWave-WPAN based on the hybrid multiple access of CSMA/CA and TDMA. To study the throughput, we make a novel analytical model for the hybrid multiple access. Our throughput analysis shows that the throughput is highly affected by the access time of CSMA/CA. A larger access time of CSMA/CA will cause a lower data transmission time in TDMA, while a lower access time of CSMA/CA will also cause a higher collision that leads to increase the unused time for data transmission. This paper provides the approximated optimum access time of CSMA/CA maximizing the throughput. Furthermore, this paper introduces a private channel release time method for reducing collisions that highly improves the throughput of the mmWave-WPAN.

This paper studies the system throughput of the 802.15.3c WPAN by considering the different wireless multiple access methods of CSMA/CA and hybrid CSMA/CA and TDMA. We construct an analytical model to study the throughput and the conducted analysis clearly shows the system throughput of the 802.15.3c WPAN upon both CSMA/CA and hybrid CSMA/CA and TDMA. We have found that CSMA/CA-TDMA can achieve much higher throughput compared to CSMA/CA, especially as the increase in the contending devices of a network.

This paper studies communication channel assignment in IEEE 802.15.3 WPANs. We clarify the channel interference problems as well as introduce an interesting channel interference caused by a hidden PNC in IEEE 802.15.3 WPANs. In this paper, we propose a predictive channel assignment method (PCAM) to efficiently avoid the channel interference among piconets and to minimize throughput degradation by channel interference. The basic idea of the proposed method is to synchronize the communication channel time among the piconets residing in the channel interference area, to predict the future channel interference time and to make a schedule of the communication channel time to minimize throughput degradation. The obtained results show that the proposed PCAM highly improves the system throughput by avoiding channel interference compared to the existing method of IEEE 802.15.3 WPANs.

Abstract-The paper proposes a codebook design to support beamforming mechanism in a wide band millimeter-wave 60 GHz wireless personal area networks (60 GHz WPANs) in a realistic millimeter-wave environment. The codebooks are designed symmetrically in order to mitigate the possible beam shift due to the large differences of wave lengthes at different sub-bands of a wide band communication system. In order to provide a high data rate and high performance with minimum power consumption in 60 GHz systems, the codebooks are generated with 90 degree phase resolution without amplitude adjustment. The codebooks are designed for different numbers of antenna elements, supporting a multitude of antenna configurations. The paper provides codebook design mechanism, some example codebooks and some analysis on antenna gain loss due to phase shift errors of phase shifters. Simulation results shows that: (1) To keep the gain loss at the intersections of any two patterns inside the codebook lower than ldB, the number of patterns inside the codebook shall be at least 2 times of the number of antenna elements used for pattern generation; (2) The designed codebooks are robust to phase shift errors: the gain loss is lower than ldB with only 10% outage probability when standard deviation of phase shift errors at phase shifters is 0.5 [28.6 degree]. The proposed codebooks are a feasible design, they are the key basis of the beamforming protocol in 60 GHz WPANs (IEEE 802.15.3c).

This paper studies the throughput of the IEEE 802.15.3c millimeter-wave (mm-Wave) WPAN system that is based on the hybrid multiple access of CSMA/CA and TDMA. In order to study the throughput of this system, we construct a novel analytical model by considering hybrid multiple access. Our throughput analysis shows that the throughput is significantly affected by the length of access time of CSMA/CA. A large length of access time of CSMA/CA will cause a low data transmission time in TDMA, while a short length of access time of CSMA/CA will cause a large number of data transmission collisions in CSMA/CA. The failure of data transmission channel release due to the collisions will lead to an increase in the unused data transmission time in TDMA. In order to improve the throughput, we introduce a private channel-release time to avoid the failure of data transmission channel release and provide the optimum access time of CSMA/CA, thereby maximizing the throughput. The proposed method can significantly improve the throughput of the IEEE 802.15.3c mm-wave WPAN system.

In order to realize high speed, long range, reliable transmission in millimeter-wave 60 GHz wireless personal area networks (60 GHz WPANs), we propose a beamforming (BF) protocol realized in media access control (MAC) layer on top of multiple physical layer (PHY) designs. The proposed BF protocol targets to minimize the BF set-up time and to mitigate the high path loss of 60 GHz WPAN systems. It consists of 3 stages, namely the device (DEV) to DEV linking, sector-level searching and beam-level searching. The division of the stages facilitates significant reduction in setup time as compared to BF protocols with exhaustive searching mechanisms. The proposed BF protocol employs discrete phase-shifters, which significantly simplifies the structure of DEVs as compared to the conventional BF with phase-and-amplitude adjustment, at the expense of a gain degradation of less than 1 dB. The proposed BF protocol is a complete design and PHY-independent, it is applicable to different antenna configurations. Simulation results show that the setup time of the proposed BF protocol is as small as 2% when compared to the exhaustive searching protocol. Furthermore, based on the codebooks with four phases per element, around 15.1 dB gain is achieved by using eight antenna elements at both transmitter and receiver, thereby enabling 1.6 Gbps-data-streaming over a range of three meters. Due to the flexibility in supporting multiple PHY layer designs, the proposed protocol has been adopted by the IEEE 802.15.3c as an optional functionality to realize Gbps communication systems.

Because of the unknown position of devices in ad-hoc network, it is difficult for the MAC to discover other devices by using directional antenna. This device discovery procedure needs extra signaling and costs considerable time, especially if there are a lot of devices. In this paper, on top of IEEE 802.15.3 MAC, we introduce the ultra superframe concept and propose an on-demand device discovery mechanism that significantly reduces signaling overhead, therefore speeds up the device discovery process and increases channel efficiency. Computer simulations show that, assuming up to 64 uniformly distributed devices, this MAC enhancement accomplishes device discovery procedure within 200 ms while keeping channel efficiency over 70% under 60 GHz channel environment.

Cognitive wireless ad hoc is highly focused as a promising future wireless technology. However, cognitive wireless ad hoc networks have some difficulties of neighbor discovery and routing. For helping neighbor discovery and routing in the cognitive wireless ad hoc networks, we introduce a common link control radio (CLCR) that is a common active wireless system of cognitive terminals. In addition, we propose a novel cognitive ad hoc routing protocol based on a common link control radio (CLCR) called a minimum weight routing protocol. We show that the proposed routing protocol can greatly reduce communication overhead in cognitive wireless ad hoc networks.

This paper proposes an air interface for ultra high-speed millimeter wave (60 GHz) systems which have been under standardization process at IEEE 802.15.3c: the proposed channel plan permits ease of portable device implementation employing the major crystal oscillator used in CDMA cellar phones. The proposed transmission modes offer much greater scalability, covering from several tens Mbps to over 4 Gbps. The proposed preamble employs Golay codes, providing sufficient robustness against wireless environment being subject to the characteristics of millimeter wave with reduced hardware complexity. Common mode is a novel technique to communicate with single carrier (SC) and OFDM camps with multi rates up to around 1.5 Gbps. This technique gives the proposed systems easy expandability from SC to OFDM or other SCs and vice versa.

To achieve ultra high speed (several gigabits/s) transmission over 60 GHz system efficiently, this paper proposes Automatic Device Discover (ADD) and frame aggregation. The computer simulation results show good feasibility of handling directional antenna for ultra high speed transmission and highly efficient transmission up to 87 percent over 4.094 Gbps PHY-SAP with 8PSK modulation.