WBANs provide communication services in the vicinity of the human body. Since WBANs utilize both MICS frequency band for implant medical applications and ISM frequency band for medical and consumer electronics (CE) applications, MAC protocols in WBAN should be designed considering flexibility between medical and CE applications. In this letter, we identify the requirements of WBAN MAC protocols and propose a WBAN MAC protocol which satisfies the requirements. In order to provide transmission flexibility for various applications, we present the dynamic CFP allocation and opportunity period. Extensive simulation results show that the proposed protocol achieves improved throughput and latency in WBAN environment compared with IEEE 802.15.4.

We first model the formal security model of multisignature scheme following that of group signature scheme. Second, we prove that the following three probabilistic multisignature schemes based on a trapdoor permutation have tight security; PFDH (probabilistic full domain hash) based multisignature scheme (PFDH-MSS), PSS (probabilistic signature scheme) based multisignature scheme (PSS-MSS), and short signature PSS based multisignature scheme (S-PSS-MSS). Third, we give an optimal proof (general result) for multisignature schemes, which derives the lower bound for the length of random salt. We also estimate the upper bound for the length in each scheme and derive the optimal length of a random salt. Two of the schemes are promising in terms of security tightness and optimal signature length. In appendix, we describe a multisignature scheme using the claw-free permutation and discuss its security.

This paper introduces 12 channel reservation techniques for medium access control (MAC) protocols suitable for high bit-rate wireless communication systems. The first 7 algorithms, namely CFP, CAP, COP, COP+SPL, CFP+SPL, UNI and UNI+LA, are applicable to systems with single-access chance per frame, whereas the other 5 algorithms, namely MT-CFP, MT-CFP+SPL, MT-UNI, MT-UNI+LUA and MT-UNI+LUT are suitable for systems with multi-access attempts per frame. The performance of these techniques are analytically evaluated and compared with the existing known techniques. The analytical model derived here are also validated through Monte Carlo computer simulations. Numerical results show that all proposed techniques are in general more superior to conventional reservation techniques. Finally when comparing between all proposed schemes in terms of both throughput performance and practical feasibility it is found that the MT-UNI+LA scheme are relatively efficient and suitable for practical applications.